COMMISSION ON POWDER DIFFRACTION
INTERNATIONAL UNION OF CRYSTALLOGRAPHY
http://www.iucr.org/iucr-top/comm/cpd/

NEWSLETTER No. 26, December 2001
http://www.iucr.org/iucr-top/comm/cpd/Newsletters/

IN THIS ISSUE

Rietveld Refinement from Powder Diffraction Data
(Robert Dinnebier, Editor)

CPD chairman’s message, Paolo Scardi

2

CPD projects:2

Quantitative Phase Analysis RR, Ian Madsen

Editor’s message, Robert Dinnebier

2

Thirty five years ago, Hugo Rietveld

3

WWW sites related to Powder Diffraction

5

IUCr Commission on Powder Diffraction

5

Rietveld Refinement from Powder Diffraction Data
Beyond the abilities of Rietveld analysis: MEM-based
pattern fitting with synchrotron X-ray powder diffraction data
7
Fujio Izumi and Takuji Ikeda
Anisotropic Peak Broadening in High Resolution Dataon RbC60
9Peter W. Stephens and Ashfia Huq
Recent developments of the program FULLPROF
Juan Rodríguez-Carvajal

12

Rietveld Refinement and Beyond
David E. Cox

20

Dealing with unknown impurity phases
W.I.F. David

30

Rietveld refinements with JANA2000
Michal Dušek, Václav Petricek, Markus Wunschel,Robert E. Dinnebier and Sander van Smaalen

32

Computer Corner, L M D Cranswick

35

Meeting and School Reports
3rd Size-Strain Conference

41News from ICDD

42

News from IXAS

44What’s On

44

How to receive the CPD Newsletter

47

Companies

47

Calls for contributions to CPD newsletter 27

47

Accuracy In X-ray Powder Diffraction: A Comparisonof Quantitative Methods
21
Nicola V.Y. Scarlett and Ian C. MadsenInternet Available Rietveld Software
Lachlan M. D. Cranswick

24

ISSN 1591-9552
Poste Italiane S.P.A. – Tassa Pagata / Taxe perçue – Stampe non periodiche – Aut. DC/DCI/TN 349/2000/MF del 08.09.2000

CPD Chairman’s Message 26
The international activity concerning Powder Diffraction will be quite rich in 2002. The major events are the 8th European
Powder Diffraction Conference (EPDIC 8) in Sweden (Uppsala, 20-23 May; http://www.mkem.uu.se/epdic8) and the XIX
IUCr World Congress in Switzerland (Geneva, 6-14 August; http://www.kenes.com/iucr/ ). The programs of two conferenceswere designed following different philosophies: while the EPDIC mostly focuses on methodologies, through dedicated sessions, the IUCr conference includes several sessions (microsymposia) on different PD applications. Despite the vicinity of thetwo conferences, attending both is therefore an interesting perspective. Same consideration applies to the 51st annual Denver
X-ray conference (Colorado Springs, 29.7-2.8.2002, http://www.dxcicdd.com), whose PD program is rich as usual.
In this frame considerable attention will be given to the Rietveld method and to the many emerging related applications. The
present issue of the CPD Newsletter is mainly devoted to this broad topic and provides a sufficiently wide variety of new
methods and applications, as well as revision of existing software and algorithms. Even if not exhaustive, this review of recent
developments can be an useful update for experts and a valid starting point for novices; even more so since the scientific articles which compose the core of the present issue are completed by the detailed review on new software (Rietveld method andother PD software) by Lachlan Cranswick. The issue is enriched by the short introduction by Hugo Rietveld who recalls theearly times when the method bearing his name was conceived.
Once more, thanks to guest editor Robert Dinnebier and to the many contributors, we can expect No 26 will be an usefulreading for the nearly 2000 powder diffractionists currently receiving the paper copy, and for the many other who download
the electronic-format newsletter from the CPD web site.
Paolo Scardi

CPD projects
Quantitative Phase Analysis Round Robin
The International Union of Crystallography (IUCr) Commission on Powder Diffraction (CPD) has sponsored a round robinon the determination of quantitative phase abundance from diffraction data. The first of two papers detailing the outcomes ofthis study has now been published (Madsen et al, 2001) and the results presented and discussed at APD III (Accuracy in Powder Diffraction III, 22-25 April 2001, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, USA).
The aims of the round robin have been detailed in Madsen et al (2001) and summarized in Issue 22 of this newsletter. The first
paper (Madsen et al., 2001) covered the results of sample 1 (a simple three-phase mixture of corundum, fluorite and zincite).
The remaining samples used in the round robin covered a wide range of analytical complexity, and presented a series of different problems to the analysts. The results pertaining to these samples are discussed in the second paper which is currently inpress. The analytical problems included severe preferred orientation (sample 2), the analysis of amorphous content (sample3), microabsorption (sample 4), complex synthetic bauxite and natural granodiorite mineral suites along with complex pharmaceutical mixtures with and without an amorphous component.
The outcomes of the second part of the round robin support the findings of the initial study. The presence of increased analytical problems within these samples has only served to exacerbate the difficulties experienced by many operators with thesample 1 suite. The major difficulties are caused by lack of operator expertise and become more apparent with these more
complex samples. Some of these samples also introduced the requirement for skill and judgement in sample preparation techniques. The second part concluded that the greatest physical obstacle to accurate QPA for X-ray based methods is the presenceof absorption contrast between phases (microabsorption) and may prove to be insurmountable in many circumstances.
Ian Madsen
References
Madsen, I.C., Scarlett, N.V.Y., Cranswick, L.M.D. and Lwin, T. (2001) “Outcomes of the International Union of Crystallography Commission on Powder Diffraction Round Robin on Quantitative Phase Analysis: Sample 1A to 1H” J. Appl. Cryst.
(2001), 34, 409-426.
(The paper can be freely downloaded from the CPD web-site as an annex to the CPD Newsletter No 25. Courtesy of the IUCr
editorial office.)

From the Editor of Newsletter 26
The basic idea behind the Rietveld method is to calculate the entire powder pattern using a variety of refinable parameters andto improve a selection of these parameters by minimizing the weighted sum of the squared differences between the observed
and the calculated powder pattern using least squares methods. That way, the intrinsic problem of the powder diffraction
method with systematic and accidental peak overlap is overcome in a clever way. It was the intention of Hugo Rietveld, whoinvented the method a few decades ago, to extract as much information as possible from a powder pattern. At the beginning
this was mainly restricted to atomic positions from neutron diffraction patterns. On the other hand, there is much more information hidden in a powder pattern which may be subjected to Rietveld refinement as the scheme below may illustrate.
2

Information content of a powder pattern

Therefore it was only a question of time before
researchers started to extract this information
using Rietveld’s algorithm. Nowadays, applications of the Rietveld method range from the reReflections
Backgroundfinement of small protein structures to standardless quantitative phase analysis, the latter beingof significant industrial importance. The availPosition
Intensity
ProfileSample Scattering from
(FWHM, peak shape)
ability of high resolution synchrotron and neusample holder,
air etc.
tron radiation with little instrumental contribution to the line shape enables the analysis of
Instrument
SampleCompton scattering
microstructural properties. As an example, thefunctionbroadening
Thermal diffuse scattering
special distribution of the lattice strain can be
deduced from anisotropic peak broadening durLattice parameters,
Crystal structure
Real structure:
Amorphous fraction
ing a Rietveld refinement. A lot of information
Pair distribution function: Space group:
Atomic positions
Strain,about defects and disorder is hidden in the backTemperature factor
Qualitative phase
Occupancy
local order/ disorder
Domain size,... ground of a powder pattern and when the nor(Disorder)
analysismalized powder diffraction data are Fouriertransformed into real-space coordinates the
Quantitative
phase analysis
atomic pair distribution function can be obtained
which allows one to investigate the local structure in parallel to the average crystal structure.
Simultaneous Rietveld refinements of several datasets can e.g. be used for full texture analysis. In general, fast detectors like
image plate readers in combination with powerful microcomputers reveal a new aspect of Rietveld-refinement: time dependence. By recording full powder patterns in short time intervals, the change of the crystal structure in dependence on pressure,temperature or during a chemical reaction is monitored and dynamical processes can be visualized. Not to forget that the
Rieveld decomposition formula can be iterated in a way that at the point where calculated structure factors |F| are entered a setof identical |F| is given instead. The Rietveld refinement then calculates a set of "|Fobs|" from the decomposition formula,which are then used as new |Fcalc| and so on, which is generally known as the LeBail method. This trick allows one to separate
the refinement of the profile from the refinement of the crystal structure and the extracted intensities can be used for crystal
structure determination. There is still a lot more potential in the method and it is my pleasure to devote an issue of the CPD
newsletter to some of the various aspects of modern Rietveld refinement.
Robert Dinnebier

Thirty five years ago
Thirty five years ago in the search for mechanically stable fuel elements for nuclear reactors, the structure of some uranates
had to be determined. Because of the small crystal size only powder diffraction data were available. This restriction was animmense obstacle, because in those days only single crystal diffraction data could lead to a successful refinement. Powder diffraction was regarded to be obsolete for refining structures, because of the problem of overlap with low symmetry compounds
and at high diffraction angles. Step scanning yielded a powder diagram that showed definite detail in the profile of these overlapping peaks. The information contained in this detail could however not be extracted by conventional means and one had toresort to taking the sum of these overlapping peaks as data for the least squares refinement. It was therefore clear that no fulluse was made of the information contained in the powder diagram.
My experience with computers, built up over years of doing single crystal diffraction work, gave me a head start in tackling
this problem of extracting the maximum of information from a powder diagram. My efforts ultimately led to what is now
known as the Rietveld Method. When the method was first reported in Moscow in 1966 at the IUCr Congress, there was hardly
any response. A few years later, when I wrote a more comprehensive computer program, first in Algol 60 and later in FortranIV, the demand for the program and its subsequent use increased, but only for neutron powder work. When the program wasadapted to X-ray diffraction by others, in the mid seventies, did the popularity of the Rietveld Method grow. I already had
foreseen that it could be used for X-ray data, but due to the lack of an actual problem, I did not pursue it any further.
I am totally amazed looking at the ever increasing use that is being made of the method. Yearly, hundreds of publications use
or refer to the method. What began as a solution for a particular problem, turned out to be a tool of much broader value. Now it
is not only applied to structure refinement, but also to such divers fields as quantitative phase analysis, measurement of strain
and size and the analysis of time-resolved data. I am deeply gratified that I could have been instrumental in reviving the powder diffraction method. This in itself would have given me enough satisfaction. Receiving the Gregori Aminoff Prize in 1995
from The Royal Swedish Academy of Sciences for my work gave an added lustre.
Hugo Rietveld

3

4

WWW sites related to powder diffraction
The Commission on Powder Diffraction (CPD): http://www.iucr.org/iucr-top/comm/cpd/
The International Union of Crystallography (IUCr): http://www.iucr.org
The International Centre for Diffraction Data (ICDD): http://www.icdd.com
The International X-ray Analysis Society (IXAS): http://www.ixas.org
CCP 14: http://www.ccp14.ac.uk/index.html
Submitting a proposal for neutron diffraction or Synchrotron Radiation X-ray Diffraction is possible at many Large Scale Facilities (LSF) in the world. It represents an important and frequently unique opportunity for powder diffraction experiments. A
useful guide and information can be accessed through the following web-site, maintained by R.Dinnebier:
http://www.pulverdiffraktometrie.de
This list is far from being complete and needs input from users and readers of the Newsletter. Please, send comments directly
to R. Dinnebier (r.dinnebier@fkf.mpg.de)

THE IUCR COMMISSION ON POWDER DIFFRACTION - TRIENNIUM 1999-2002
Chairman: Prof. P. Scardi (Paolo)
Dipartimento di Ingegneria dei Materiali, Università diTrento, 38050 Mesiano (TN), Italy;
Tel: +39 0461 882417/67 | Fax: +39 (461) 881977
e-mail: Paolo.Scardi@ing.unitn.it
Secretary: Dr A. N. Fitch (Andy)
ESRF, Grenoble France
Tel: +33 476 88 25 32 | Fax: +33 476 88 25 42
e-mail: fitch@esrf.fr
Dr R. Delhez (Rob)
Laboratory of Materials Science, Delft University of Technology, Rotterdamseweg 137 2628 AL Delft, The Netherlands
Tel: +31 15 2782261 | Fax: +31 (15) 278 6730
e-mail: R.Delhez@tnw.tudelft.nl

Prof. H. Fjellvåg (Helmer)
Department of Chemistry, University of OsloP O Box 1033, Blindern N0315 OSLO, Norway
e-mail: helmer.fjellvag@kjemi.uio.noProf. W. I. F. David (Bill)
Rutherford Appleton Laboratory (CCLRC), Chilton, Oxon.
OX11 OQX, United Kingdom
Tel: +44 1235 445179 | Fax: +44 1235 445383
e-mail: bill.david@rl.ac.uk
Dr R. E. Dinnebier (Robert)
Max-Planck-Institut für Festkörperforschung,
Heisenbergstrasse 1, D-70569 Stuttgart, Germany
Tel: +49-711-689-1503 | Fax: +49-711-689-1502
e-mail: r.dinnebier@fkf.mpg.de------------------------------------------------------------------

Prof. S. P. Sen Gupta (Siba)
Department of Materials Science, IACS, Jadavpur, Calcutta
700032, India; Fax. +91 (33) 4732805
e-mail: msspsg@mahendra.iacs.res.in
Dr R. B. Von Dreele (Bob)
LANSCE, Los Alamos National Laboratory, Los Alamos,
NM 87545, USA; Fax: +1 (505) 6652676
e-mail: vondreele@lanl.gov
Dr D. Balzar (Davor)
Department of Physics & Astronomy
University of Denver
2112 E Wesley Ave, Denver, CO 80208-0202
Phone: 303-871-2137 | Fax: 303-871-4405
Web: e-mail: balzar@du.edu
Prof. G. J. Kruger (Gert)
Department of Chemistry & Biochemistry, Rand Afrikaans
University, P O Box 524, Aucklandpark, South Africa
Tel: +27 11 489 2368 | Fax: +27 11 489 2360
e-mail: gjk@na.rau.ac.za

ICDD Representative
Prof. R. L. Snyder (Bob)
Department of Materials Science & Engineering, 2041 College Avenue, Ohio State University, Columbus, OH 432101179, USA; Fax: +1 (614) 2924668
e-mail: Snyder.355@osu.edu
Consultants
Prof. R. J. Cernik (Bob)
Daresbury Laboratory, daresbury, Warrington, WA4 4AD,
UK; Fax: +44 (1925) 603 124
e-mail: R.J.Cernik@daresbury.ac.uk
Dr F. Izumi (Fujio)
National Institute for Research in Inorganic Materials
1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
TEL: +81-298-51-3354 (ext. 511); FAX: +81-298-52-7449
E-mail: izumi@nirim.go.jp

56Beyond the abilities of Rietveld analysis: MEMbased pattern fitting with synchrotron X-ray
powder diffraction data
Fujio Izumi and Takuji Ikeda
Advanced Materials Laboratory, National Institute forMaterials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044,
Japan
The maximum-entropy method (MEM) is a versatile
approach to the estimation of a model from a limited
amount of information by maximizing information entropy
under constraints consistent with observed physicalquantities. In recent years, Takata et al. [1] have applied it
actively to the determination of electron densities, ρ, usingsynchrotron X-ray diffraction (XRD) data. MEM infers
electron densities in such a way that they provide themaximum variance of structure factors, Fc(MEM), withinerrors in observed structure factors, Fo. Detailed structural
information can effectively be extracted from thediffraction data and reflected on the resulting densities (ρ >0) by MEM if the data have been appropriately measured.
Because MEM can estimate non-zero structure factors ofhigh-Q reflections excluded in the analysis of powder
diffraction data, the termination effect is less marked in
MEM analysis than in Fourier synthesis. Thanks to these
excellent features, MEM gives less noisy density maps
than Fourier synthesis [2].
Takata et al. [1] estimate observed integrated intensities
on the basis of the result of Rietveld analysis when dealing
with overlapping reflections. That is, the observed net
intensity at each point is apportioned in the ratio of profiles
calculated from final structure and profile parameters andsummed up for each reflection [3]. This expedienttechnique is also utilized to evaluate RB and RF in Rietveld
analysis, integrated intensities in the Le Bail method [4],and electron/nuclear densities in Fourier synthesis.
However, ‘observed’ structure factors, Fo(Rietveld),
estimated in this manner are doubly biased towards a
structural model in the Rietveld analysis because bothphases and calculated profiles used for the intensity
partitioning are derived from the model [2]. Thisapproximate nature of the procedure for extracting
integrated
intensities
lowerstheaccuracyofelectron/nuclear densities determined by combining
Rietveld and MEM analyses, i.e., the MEM/Rietveld
method [1].
We have integrated a versatile pattern-fitting program
RIETAN-2000 and a MEM program MEED into a system
named REMEDY [5–7] to overcome the serious defect in
the MEM/Rietveld method. With REMEDY, the bias
imposed on electron/nuclear densities can efficiently be
reduced by an original technology called MEM-based
Pattern Fitting (MPF). This article describes the principleof the MPF method and its applications to XRD data ofthree samples to demonstrate its strength relative to the
MEM/Rietveld method. In contrast to our previous work
[5–10] using XRD with CuKα radiation and neutron
diffraction, synchrotron XRD data were analyzed to test
the performance of MPF in structure refinements with thehigh-resolution XRD data.
Figure 1 illustrates a flow chart of structure refinement by
the MEM/Rietveld method (upper frame) and subsequent
repetition of MPF (lower frame). Fo(Rietveld) data
estimated at the end of Rietveld analysis [3] are analyzed

Fig 1 Structure refinement by Rietveld and MEM analyses
followed by iterative pattern fitting based on MEM. A
new program to visualize crystal structures andelectron/nuclear densities is under development.

by MEM to yield electron/nuclear densities, which mayurge us to modify a structural model. Rietveld and MEM
analyses are alternately carried out until a reasonablestructural model is reached [1].
The undesirable bias imposed by the structural model
enlarges with increasing degree of overlap of reflections
and lowering resolution in a powder pattern. The
MEM/Rietveld method, which certainly serves to modify
imperfect structural models [1,8,9], is far from perfect for
determining
accurateelectron/nuclear
densities.
Nevertheless, MEM allows us to extract structural details
from the Fo(Rietveld) data because they containcontributions that have been neglected in the structuralmodel. In addition, actually observed structure factors, Fo,

Fig 2 Electron-density image of anthraquinone viewed along3[0 1 0] with an equi-density level of 0.7 e/Å and crosssections at y = 0.

can be determined for isolated reflections without any
approximation.
To minimize the bias to the structural model,
MEM/Rietveld analyses are followed by iteration of MPF.
MEED evaluates Fc(MEM) by the Fourier transform ofelectron/nuclear densities. Then, we fit the calculated
pattern to the observed one by fixing structure factors atvalues of Fc(MEM) obtained by the previous MEM
analysis and refining only parameters irrelevant to thestructure. Fo(MPF) data estimated after the pattern fitting
according to Rietveld’s procedure [3] are analyzed again
by MEM. MEM analysis and pattern fitting are alternately
repeated until R factors in the pattern fitting no longer
decrease. Such an iterative procedure is referred to as
REMEDY cycles, as noted in Fig. 1. Repetition of MPF
weakens the influence of the structural model on Fo(MPF).
In other words, intensity repartitioning for overlappingreflections can become more accurate with increasing

capillary tubes rotated at a speed of 60 rpm. Incident
beams from an undulator were monochromatized withinclined double-crystal monochromators of Si(111). An
instrumental resolution at the top international level isattained in this diffractometer.
We expected that anisotropic thermal vibration, subtle
orientational disorder, and σ and π bonds in aromaticcompounds would not satisfactorily be depicted byconventional Rietveld analysis. Then, the MPF method
was applied to the XRD data (λ = 1.5496 Å) of
anthraquinone (C14H8O2, P21/c) [11] at room temperature.
Rwp, RB, and RF were respectively 5.37%, 3.54%, and7.13% in the final Rietveld refinement and 4.90%, 0.78%,
and 1.33% after subsequent three REMEDY cycles. Figure
2 shows an electron-density image resulting from the final
MEM analysis. C–C and C–O bonds are visible with a

Fig 3 Changes in R factors for the final Rietveld analysis andsubsequent two cycles of MPF for Sr9.3Ni1.2(PO4)7.

number of cycles owing to extraction of additional
structural information from observed intensities of Braggreflections.
The above sophisticated methodology achieves asignificant breakthrough in adequate representations ofdisordered atomic configurations, chemical bonds,
nonlocalized electrons, and anharmonic thermal motion.
Crystal structures are expressed not by structure
parameters but by three-dimensional electron/nuclear
densities in MPF. Therefore, the above purposes are
attainable more satisfactorily by the MPF method than by
the conventional Rietveld method. The establishment of
this technique leads to the availability of an ultra-highresolution ‘X-ray/neutron microscope’ that enables us tovisualize powder diffraction data as three-dimensional
density images. X-Ray and neutron diffraction can be

Fig 4 Observed, calculated, and difference patterns fo the last
MPF for Sr9.3Ni1.2(PO4)7. The patterns between 20° and
48° are magnified in the inset.

utilized complementarily for (a) more adequate expressionof chemical bonds and (b) analysis of anharmonic thermal
vibration and disordered structures [10], respectively.
The synchrotron XRD data of the three samples were
measured on a powder diffractometer (beam line BL15XU
at SPring-8) with the Debye-Scherrer geometry using

Fig 5 Observed, calculated, and difference patterns for LTL.
The patterns between 10° and 60° are magnified in theinset.

difference in expansion of the isosurface. H atoms bonded
to C atoms in benzene rings look like mamillae.
XRD
data
of
a
whitlockite-like
phosphate,
Sr9.3Ni1.2(PO4)7 (R3m) [12], were taken at 100 K with awavelength of 0.8000 Å and a Ge(111) analyzer. Most
sharp profiles could be observed with FWHM ranging
from 0.008° to 0.019°. In the structure of Sr9.3Ni1.2(PO4)7,
parts of Sr2+ and PO43– ions exhibit highly disorderedarrangements, which cannot be well expressed by a splitatom model in its Rietveld analysis. Rwp, RB, and RF
respectively decreased from 7.38%, 3.87%, and 2.88% in
the final Rietveld refinement adopting a split-atom model
to 6.23%, 1.25%, and 0.95% after four REMEDY cycles(Fig. 3). RB and RF dropped dramatically in the first cycle.
A very excellent fit between observed and calculated
patterns was attained in the final MPF (Fig. 4). These
preliminary results reveals that the MPF method iseffective even in the structure refinement using the XRD
data measured with the very high resolution.
A dehydrated zeolite LTL (K9Al9Si27O72, P6/mmm) [13],is a microporous material with a disordered structure
including large one-dimensional channels parallel to the caxis. Its XRD data (λ = 1.2000 Å) were collected at room
temperature with the Ge(111) analyzer. Rwp, RB, and RF
were respectively 4.90%, 1.60%, and 1.59% in the final
Rietveld refinement and 4.46%, 0.69%, and 0.84% after
two cycles of MPF. Figure 5 shows the final profile fit to
be excellent. An electron-density image (Fig. 6) clearly
displays a framework consisting of highly covalent(Si,Al)–O bonds. We also found that electron-density
distribution around K+ ions incorporated in the framework
is not spherical but anisotropic.

The number of REMEDY cycles required forconvergence generally increases with lowering resolution
in a diffraction pattern because observed intensities of
Bragg reflections are repartitioned with Fc(MEM)
calculated from Fo(Rietveld) or Fo(MPF). Even with highresolution synchrotron XRD data, at least one cycle ofFig 6 Electron-density image of LTL viewed along [00 1 ]with an equi-density level of 0.5 e/Å3 and crosssections at z = 0.

MPF proved to be indispensable for the determination of
more accurate electron densities. In MPF, parameters otherthan structure parameters are refined, and partition ofobserved intensities is successively improved because of
the use of Fc(MEM). The MPF method is, hence, so muchsuperior to the MEM/Rietveld method, in which theanalytical method in the Fourier synthesis of Fo(Rietveld)
data is merely replaced with MEM [1].

Anisotropic Peak Broadening in High
Resolution Data on RbC60.
Peter W. Stephens and Ashfia Huq
Department of Physics & Astronomy, Stony Brook
University, Stony Brook, NY 11794-3800 USA
Anyone familiar with Rietveld refinements knows thatthe method depends on having an accurate model for the
powder diffraction profile. We wish to present a brief
story about data that created some disappointment when it
looked like the sample contained serious impurities, butthat was eventually resolved once we recognized that weneeded a lineshape model that was as good as the data.
Instruments with better resolution are becoming more
widely used: synchrotron radiation sources, high resolution
diffractometers at pulsed neutron facilities, and parallelbeam optics in the laboratories of individual researchers.
Data with improved resolution and counting statistics
generally reveal more information about the sample. This
is not always welcome because it demands that the user
think about (or at least model) aspects of the experimentthat may seem secondary to finding out where the atoms
are.
The one-dimensionally polymerized fullerenes AC60 (A =K, Rb, Cs) are interesting and incompletely understood.
All three are thermodynamically stable at room
temperature and below, and have a structure consisting of
chains of fullerenes linked by [2+2] cycloaddition, but

From the significant results presented above for the threecompounds, we conclude MPF to be a powerful method of
structure refinement where imperfect structuralrepresentations in conventional Rietveld analysis aresupplemented with model-free MEM.
REFERENCES[1] M. Takata, E. Nishibori, and M. Sakata, Z. Kristallogr.,
216, 71 (2001).
[2] L. B. McCusker, R. B. Von Dreele, D. E. Cox, D.
Louër, and P. Scardi, J. Appl. Crystallogr., 32, 36(1999).
[3] H. M. Rietveld, J. Appl. Crystallogr., 2, 65 (1969).
[4] A. Le Bail, H. Duroy, and J. L. Fourquet, Mater. Res.
Bull., 23, 447 (1988).
[5] F. Izumi, S. Kumazawa, T. Ikeda, and T. Ida, “Powder
Diffraction,” ed. by S. P. Sen Gupta, Allied Publ., New
Delhi (1998), pp. 24–36.
[6] F. Izumi, Rigaku J., 17(1), 34 (2000).
[7] F. Izumi, S. Kumazawa, T. Ikeda, W.-Z. Hu, A.
Yamamoto, and K. Oikawa, Mater. Sci. Forum, 378–
381, 59 (2001).
[8] T. Ikeda, F. Izumi, T. Kodaira, and T. Kamiyama,
Chem. Mater., 10, 3996 (1998).
[9] T. Ikeda, Y. Akiyama, F. Izumi, Y. Kiyozumi, F.
Mizukami, and T. Kodaira, Chem. Mater., 13, 1286
(2001).
[10]F. Izumi, T. Ikeda, T. Sasaki, and S. Kumazawa, Mol.
Cryst. Liq. Cryst., 341, 253 (2000).
[11]Y. Fu and C. P. Brock, Acta Crystallogr., Sect. B, 54,
308 (1998).
[12]A. A. Belik et al., unpublished data.
[13]R. M. Barrer and H. Villiger, Z. Kristallogr., 128, 352(1969).

there are significant differences both in their structures andin their physical properties. This observation cries out forclarification from structural studies. They were thought tobe isostructural (orthorhombic) when first discovered, but
the fact that RbC60 is monoclinic was later discovered
independently by Lanois et al. [1] and by us [2]. The realimportance of our high resolution structure solution lies in
the fact that it is the first analysis of a fulleride with lower
than cubic symmetry in which the position of every atom ismeasured. Substantial deformations from icosahedral
symmetry are observed throughout the buckyball. Indeed,
there is an overlap of the distances seen in nominally
single and double sp2 bonds. The interested reader isreferred to our full results in Reference 2; we only remark
here that it requires a very high quality refinement to haveconfidence in such unexpected results.
When we first collected data in 1998 on approximately 1
gm of material at the High Resolution Powder
Diffractometer of the ISIS pulsed neutron source, it was
obvious that the orthorhombic cell would not work, and wequickly found that a monoclinic lattice distortion of only
0.3° was required to fit the data. We quickly found a goodstarting structure, but when we got home and worked torefine it, there were several strong, sharp peaks thatappeared in the difference plot (Fig. 1a). Did our carefully
prepared sample contain impurities?
Scouring thedatabases, we found some Rb oxides, hydroxides, etc.,with some d-spacings close to our peaks, but no positive

Fig 2 Distribution of strain broadening, δd/d, from theanisotropically broadened lineshape model in the
Rietveld refinement of RbC60 discussed in the text.

Fig 1 Rietveld refinements of data on RbC60 at 200K, taken
at the time-of-flight neutron diffractometer HRPD at
ISIS. (top panel): Fit using standard Rietveld lineshapemethod, with Gaussian and Lorentzian widths asmooth (parameterized) function of reflection spacingd. This fit has. (bottom panel): Fit with anisotropic
broadening model from Ref. 3; Rwp = 1.48%, χ2 = 4.33.

identification. It’s painful to recall the efforts we made tofind out what new phase was in our sample, and how manyold samples we rechecked with x-rays and found to besignificantly contaminated by the same phase. This had nopeaks observable in the raw data, and only overlapped withmeasurable RbC60 data. The last straw was the discovery
that the impurity phase disappeared when we heated a test
sample to 200°C, where the fulleride transforms into a
cubic rock-salt structure. Actually, we probably shouldhave noticed earlier that all of the peaks in the difference
curve actually coincided with allowed diffraction peaks
from the polymeric fulleride structure, and indeed that they
are reflections on or very close to the polymeric chain axis.
So if these extra-sharp peaks are intrinsic to the structure,

we need to ask two questions: Why? What can be done
about it? Tackling the second one first, we should
remember that the premise of Rietveld refinement is toparameterize the diffraction lineshape in some meaningful
way, so that the data can help to do an optimal job ofassigning the intensity at a given observed point in the
spectrum to the appropriate Bragg reflections. If the peaks
widths do not follow a smooth dependence on d-spacing,that can be modeled just like any other set of refineableparameters. There have been numerous observations of the
problem, and attempts to deal with it. However, it isimportant that any such phenomenological account oflineshape broadening should respect the symmetry of the
problem, e.g., so that peaks with symmetry equivalent
Miller indices should have the same width. Several
authors, including one of us (PWS) had previously shownthat certain kinds of anisotropic strain broadening can be
described by a model incorporating quartic combinationsof Miller indices [3]. This was originally justified as themost general joint distribution of lattice metric parameters,
but has been more recently tied to distributions of elasticstrains caused by defects, at least for cubic and hexagonal
systems, and can be used to determine density andarrangement of dislocations [4].
A Rietveld refinement with the nine anisotropic
broadening coefficients is shown in Fig. 1b. Clearly, themodel has taken care of the family of extraordinarily sharp
peaks that were so upsetting in Fig. 1a. It is interesting tolook at the microstrain distribution that results from thisrefinement. That is illustrated in Fig. 2, which shows thewidth of the distribution in microstrain, δd/d, as a functionof direction in reciprocal space. The cusp facing theviewer is in the direction of the monoclinic b axis, which isthe chain axis. This agrees with intuition that the structure
should be most rigid along the chains of covalently linked
buckyballs, and would have more flexibility in otherdirections, where the bonding is van der Waals. We
emphasize that the parameters all have a physical meaning(albeit somewhat obscure), compatible with the structuralsymmetry of the material. This is not the case with otherapproaches, which, e.g., model microstrain as anellipsoidal function of direction of the Bragg diffraction
direction relative to the crystalline translation axes.
In this example, we have seen that a reassessment of thediffraction lineshape led to a qualitative change in theevaluation of the experiment: there is nothing wrong withthe sample and the result is a valid solution of thestructure. However there is also a less dramatic, but
quantitatively important improvement in the quality of therefined parameters. The statistical esd’s are smaller,
generally by a factor of two, with the anisotropic lineshapemodel. One expects this because χ2 is smaller by a factor
of about four, due to the improved fit. But we also see thatthe refined bond lengths shift, typically by twice the esd
from the Rietveld of the isotropic lineshape model. That
shift is probably significant, and is a real benefit of the
improved fit. More broadly, we would like to point out
that about half of the samples that we have recently
investigated by high resolution powder diffracometry haveshown significant anisotropic strain broadening.

Clearly it is imporant to include this effect in any
analysis of high resolution data.
Currently, it is
implemented and documented in only one Rietveld
program, GSAS.
REFERENCES[1] P. Launois, R. Moret, J. Hone, and A. Zettl, Phys. Rev.
Lett. 81, 4420 (1998).
[2] A. Huq, P.W. Stephens, G.M. Bendele, and R.M.
Ibberson, Chem. Phys. Lett. 347, 13 (2001).
[3] P.W. Stephens, J. Appl. Cryst. 32, 281 (1999); see also
C. Popa, J. Appl. Cryst. 31, 176 (1998).
[4] G.Ribarik, T. Ungar, and J. Gubicza, J. Appl. Cryst. 34,
669 (2001).

8th European Powder Diffraction Conference

Uppsala, Sweden
23 - 26 May 2002

Information and application forms:
Internet: http://www.mkem.uu.se/epdic8
e-mail: epdic8@mkem.uu.se
Tel/Fax: +46-18-4713733 / +46-18-513548

Recent developments of the program FULLPROF
J. Rodríguez-Carvajal
Laboratoire Léon Brillouin (CEA-CNRS), 91191 Gif
sur Yvette, FRANCE. andService de Physique Statistique, Magnétisme et Supraconductivité, CENG (CEA), 38400 Grenoble Cedex 9,
FRANCEIn these notes some of the most recent developments ofthe program FullProf are presented. After an introduction
summarizing the most important changes we present, in
more detail, few examples selected among those of more
usefulness for a majority of people: a) the introduction of
special form factors for treating nearly free rotating
molecules, b) the use of the simulated annealing procedure
for solving crystal and magnetic structures and c) the newfeatures related to microstructural effects. The notes finish
enumerating some of the projects already in course thatwill be publicly available soon in 2002.

2.

3.

to the user of the program. In particular automatic
calculation of the multiplicity of each site is now
performed after reading the atoms as well as thecalculation of the appropriate coefficients for automaticquantitative analysis of mixture of phases.
The calculation of distances and angles, as well as
bond valence sums can now be done automatically, without
using external programs. Output files with extension dis
contain all the relevant information for the different phases
if the user is asking for this option. A byproduct of thesecalculations is the generation of the output files of names
dconstr"n".hlp (n stands for the number of the phase)containing lines that can be directly pasted to PCR files forsoft constraints on distances and angles. This makes theuse of distance and angle constraints extremely easy inappropriate cases.
Another important modification is the handling ofrefinement codes. Now the user may select between the
traditional mode changing by hand the numbering of

F m 3 m!Atom TypC
SASH<--Space group symbol
X
Y
Z
Biso
Occ
In Fin N_t Spc/Codes
0.00000 0.00000 0.1.49934 1.00000
0
0
4
0
0.00
0.00
0.00
21.00
0.00
! Form-factor refinable parameters
!
f1
f2
f3
f4
f5
f6
f7
3.53862 60.00000 1.00000 -0.01809 0.01335 0.00453 0.02742
31.00
0.00
0.00
41.00
51.00
61.00
71.00
!
f8
f9
f10
f11
f12
f13
f14
-0.01328 0.00617 -0.00220 0.02042 0.00000 0.00000 0.00000
81.00
91.00
101.00111.00
0.00
0.00
0.00
klj
9
0 1
6 1
10 1
12 1
12 2
16 1
16 2
18 1
18 2
Fig 1: Piece of PCR file adapted for the refinement of a diffraction pattern containing C60 in its nearly free rotator phase.

1.

INTRODUCTION
From the first half of 1998 profound changes have been
introduced in the source code of FullProf. The mostimportant was the complete transformation of the sourcecode to the new standard Fortran 95, using the new syntax
and features (suppression of COMMON statements,
introduction of modules, interfaces, types, etc) [1]. This
process is being continued in order to make the whole
program based in a library of Fortran 95 crystallographic
modules [2]. The Fourier program GFourier [3] is also
based in this library. The new architecture of the program
makes it possible to introduce new changes in a very easyway.
During the last two years the development of the program
FullProf has continued also by improving its user friendly
interface (WinPLOTR for Windows) and including more
options. In particular dynamic allocation has been
introduced in order to fit the available memory to the sizeof the problem to be treated. An optimization mode has
also been introduced in order to speed up the calculations
in simple cases.
Some examples of useful changes made on the code of
FullProf are the following:
The old code generating symmetry operators from theHermann- Mauguin symbols and the code generatingreflections has been totally removed. Everything has been
substituted by Fortran 95 modules able to interpret both
Hermann- Mauguin and Hall symbols or generate the fullspace group from a small set of user-given generators [2].
These modules provide better crystallographic information

codewords controlling the refinement or select the
automatic mode. If the automatic mode is selected, a codeof the type “1.00” means that the corresponding parametershould be refined. The user may combine the manual modewith the automatic mode for making the desired
constraints. The program automatically renumber thecodes, suppress the holes in the matrix and takes care ofuser-defined constraints.

Number of independent
reflections: 141=> RF2-factor : 3.49=> RF -factor : 3.01

Fig 2: Plot of the observed (red) versus calculated (black) square
structure factors in a region of sinθ/λ, after refining the C60
molecule using a SASH form factor.

4.

5.

A new mode for refining magnetic structures has also
been included. The free parameters are then thecoefficients of the basis functions of the irreducible
representations of the propagation vector group. This mode
can also be used with the simulated annealing
optimization.
New functions for refinement of the background havebeen included. In particular the height of the linear
interpolated background points that was fixed in previous
versions of the program can now be refined.
Other improvements concerning special form-factors,
simulated annealing and microstructural effect are
discussed below in more detail.
SPECIAL FORM-FACTORS
Several types of special form factors are included in
FullProf, among them the Symmetry Adapted Spherical
Harmonics (SASH) as special form-factors are now fully
implemented. The case of C60 is provided as an example
using cubic harmonics in Figure 1.
The program knows that the user is giving a special formfactor by putting the value N_t=4 in the same line of giving
the chemical species, the keyword of the form-factor andthe fractional coordinates. The user must provide the typePara-di-Iodo-Benzene (Sim.Annealing)!
!Nat Dis Ang Pr1 Pr2 Pr3 Jbt Irf Isy Str Furth
60
0 1.0 0.0 0.0
4
4
0
0
0
!
P b c a<--Space group symbol!Atom Typ
x
y
z
B
!
d
theta
phi
X0
Y0
Pi1 I
0.17439 0.04548 -0.30989 0.00000
0.00
0.00
0.00
0.00
3.50000 -0.09100 -0.09100 0.00000 0.00000
0.00
0.00
0.00
0.00
0.00
Pi2 C
0.06946 0.01811 -0.12342 0.00000
0.00
0.00
0.00
0.00
1.39400 -0.09100 -0.09100
0.00
0.00
0.00
. . . . . . . . . . . . . . . . . . .

X-ray scattering factor). The angles used as arguments inthe above expressions correspond to the sphericalcoordinates of the scattering vector Q with respect to a
local Cartesian frame that may be the same or different as
the default Cartesian frame connected with the
crystallographic unit cell. In the last case a transformation
matrix should be given.
The coefficientsscljs and clmp
are free parameters. In

FullProf the form-factor corresponds to just one shell (aparticular value of s). For a complete molecule the user
must provide a number of SASH objects equal to thenumber of spherical shells characterizing the molecule.
The first parameter in the list (f1, f2, f3, …) corresponds tothe value of the spherical shell radius: f1=rs, the second
parameter is the number of atoms of the chemical species
given by the chemical symbol, within the spherical shell.
The coefficients (f3, f4, f5, …f14) correspond to the freessparameters clj or clmp of the current shell in the orderspecified by the list. The first coefficient f3 corresponds tothe free rotator term l = m = 0 (or l = j = 0) and should,
normally, be fixed to 1. The user must provide the list (l,m, p), or (l, j), in ascending order on l according to the local

ATZ
Nvk Npr More
0.00
0
0
0

Occ
P6
Z0
CHI
1.00000 1.00000
0.00
0.00
0.00000 -2.62905
0.00
31.00
1.00000
0.00

THETA
P16:SAT
2.0554811.00
0.00000

PHI

Spc

0.06590
21.00

0

0

! Limits for selected parameters (+ steps & BoundCond for SA):1
0.00003.14160.50001
Theta
2-3.1416
3.14160.50001
Phi
3-3.1416
3.14160.50001
Chi! T_iniAnneal Accept NumTemps NumThCyc InitConf
8.000
0.900
0.020
80
0
0
! NCyclM
Nsolu Num_Ref Nscalef NAlgor
200
1
71
1
1

Fig 3: Part of a PCR file showing the use of the simulated anneling method to determine the orientation of the molecule of I2C6D4.
The center of the molecule is at the origin and only three angles are needed to fix the position of the molecule in the unit cell.

of SASH to be used (real spherical harmonics or cubic
harmonics) using a particular label. In the case of C60 thelabel klj instructs the program for using cubic harmonics.
The number of terms (9 in the present case) and the indices(list of pairs of integers in the line following klj) of theharmonics to be used according to the symmetry of boththe site and the molecule.
The form-factor SASH is well adapted to nearly freemolecular rotations. For a molecule with N atoms rotatingaround its center of mass (supposed to be in a particular
crystallographic site)the molecular form factor is given by:
Where the index s runs from 1 to N and corresponds to N
spherical shells. jl(x) is the sphericalBessel function of order l. Klj(θ,ϕ) and ylmp(θ,ϕ) and are the
cubic harmonics and the real spherical harmonics,
respectively, as defined in [4]. bs is the scattering length (orsite symmetry. See Table 2 in the above reference.
Another form-factor that may be quite useful is the formfactor called: ANOM. It may be used to let refine theanomalous dispersion correction of the scattering factor ofan atom showing a strong anomalous scattering. The
format is similar to the general case of a special formfactor, the chemical symbol must be used as label of theatom, the real and imaginary components of the dispersion
correction are stored in f1 and f2.
SIMULATED ANNEALING
An option for helping to solve crystal and/or magnetic
structures has been included. This is a simulated annealing
module able to handle two types of algorithms: fixed andvariable steps for generating new configurations. The
simulated annealing technique works, at present, only withintegrated intensities. A short report about the techniqueand the implementation in FullProf may be found inreference [5], here we show just some examples of using
the method .
To solve a crystal or a magnetic structure a complete listof atoms with all their attributes (thermal parameters,
magnetic moments, etc) should be given as if everything
were known. An example of simulating annealing PCR fileis given in Figure 3.
The use of codewords is totally supported so that any
usual constraint may be used in the search. Of course theinitial values of the parameters are arbitrary provided thehard constraints through the codewords are respected. Infact the meaning of the codewords is the same as in leastsquare refinements, the multipliers and signs are applied tothe shifts with respect to the previous values of theparameters. The scale factor may be treated automaticallyso that no codeword should be given to this parameter.
The program recognizes the use of simulated annealing
by putting NRELL equal to the number of parameters to beeventually varied, and ICRYG=3 in the beginning of the
PCR file (see appendix of the manual for details).
In the example above the three angles (in radians)
defining the orientation of the molecule are selected asparameters 1, 2 and 3. The admissible range of values are
given in a list followed by an indicator telling to theprogram how to treat the boundaries. The number “1”following the value of the initial step (0.5 radians)
indicates that periodic boundary conditions are applied.
The flag InitConf is important for selecting the treatmentof the initial configuration. If InitConf = 0 the initialconfiguration is totally random. If InitConf =1, the initialconfiguration is the one given by the values of theparameters in the PCR-file. This last option is useful when
one tries to optimize an already good starting
configuration, by controlling the box limits and the steps.
The other critical point is to select between the twoalgorithms. This is controlled by the value of the variable
Nalgor. If its value is zero, the Corana algorithm isselected. This algorithm does not use fixed steps formoving the parameters defining the configuration, instead
the program starts by using then whole admissible interval
as initial step for all parameters and then adapt
progressively their values in order to maintain an
approximate rate of accepted configurations between 40%
and 60%. If Nalgor =1 the same algorithm is used but thestarting steps are those given in the file. For Nalgor =2, thenormal SA algorithm (fixed steps) is used. The last
method, used with appropriate boundary box forparameters and InitConf =1, is better when one tries torefine a configuration without destroying the starting
configuration.

=> **** SIMULATED ANNEALING SEARCH FOR STARTING CONFIGURATION ****=> Initial configuration cost:
77.53=> Initial configuration state vector:
=>
Theta
Phi
Chi
=>
1
2
3
=>
1.38072.4672 -3.0110=> NT: 1 Temp: 8.00 (%Acc): 23.50 <Step>: 5.2360 <R-factor>: 44.4302. . . . . . .

=> NT:

6 Temp:4.72 (%Acc): 30.50<Step>:

0.3496<R-factor>: 23.8774

2.79 (%Acc): 39.33<Step>:

0.1440<R-factor>: 13.4990

0.97 (%Acc): 38.50<Step>:

0.0530<R-factor>:

6.34170.27 (%Acc): 36.17<Step>:

0.0179<R-factor>:

4.3854. . . . . . . .

=> NT: 11 Temp:. . . . . . . .

=> NT: 21 Temp:. . . . . . . .

=> NT: 33 Temp:=>BEST CONFIGURATIONS FOUND BY Simulated Annealing FOR PHASE:=> -> Configuration parameters (71 reflections):=> Sol#: 1 RF2=
3.928 ::
=>
Theta
Phi
Chi
=>
1
2
3
=>
0.94010.14642.7477=>
CPU Time:
25.177 secondsð0.420 minutes
ð1

Fig 4: Simplified screen capture of the FullProf output when running in the simulating annealing mode for the example of figure 3. The
first picture of the structure corresponds to the starting configuration. The final result is also displayed.

Fig 5: Different stages of the trajectories of configurations (projections in the ab plane) in a simulated annealing run for thedetermination of the structure of PbSO4 from neutron powder diffraction data using overlapped integrated intensities. Lead atoms(b= 0.94 ) are found first (at 40% of the total run time), oxygen atoms (b= 0.58) in a second stage and finally (at about 54% ) thesulphur atoms (b= 0.285) start to remain into their oxygen tetrahedra.

Within the distribution of FullProf there is a simple
example of simulating annealing work using neutron
diffraction data from D1A on lead sulfate PbSO4. In thisexample the atoms are treated independently using thecorrect space group and an artificial constraint is used:
several atoms are constrained to have the same y fractional
coordinate. We know that all these atoms are in a special
position of the Pnma space group (y should be ¼ or ¾), but
the file is prepared in such a way as to illustrate the use of
constraints. Starting from a random configuration for all
the free parameters (including the special y’s) the programfinds progressively the good atom positions when theappropriate values of the control parameters are used (seefigure 5).

The user should experiment for each own case in order toselect good control parameters. For instance theappropriate starting temperature depends strongly on thenumber of free parameters, the step sizes and theconstraints. For solving a structure (crystallographic or
magnetic) from the scratch it is important to select atemperature for which the percentage of accepted
configurations is high (or the order of 80%) in order to let
the procedure explore a large set of configurations. The
Rietveld refinement cycles together with Fourier synthesis.
For using the GFourier program [3], distributed in thesame site that FullProf , it is important to use the value
Jfou=4 in the PCR-file, to output an appropriate set ofstructure factors and an input file (extension inp) for
GFourier.

combination) are considered as stochastic variables with acorrelations between metric parameters [9].
1
M hkl = 2 = Ah 2 + Bk 2 + Cl 2 + Dkl + Ehl + Fhk = M (αi ; hkl )d hkl

MICROSTRUCTURAL EFFECTS
The microstructural effects within FullProf are treatedusing the Voigt approximation: both instrumental andsample intrinsic profile are supposed to be described
approximately by a convolution of Lorentzian andGaussian components. The TCH pseudo-Voigt profile
function [6] is used to mimic the exact Voigt function and
it includes the Finger‘s treatment of the axial divergence[7]. The integral breadth method to obtain volume averagesof sizes and strains is used to output a microstructural filewhere an analysis of the size and strain contribution toeach reflection is written. No physical interpretation is
given by the program, only a phenomenological treatmentof line broadening in terms of coherent domain size andstrains due to structural defects is performed. The user
should consult the existing broad literature to go further
in the interpretation of the results. A recent book [8],σ 2 ( M hkl ) = ∑ C ij
i, j

∂M ∂M
= (h 2∂α i ∂α j

k2

l2

kl

gathering different articles, is a good introduction to
microstructural problems.
The new file containing information about the
microstructure is output only if the user provides an input
file containing the instrumental resolution function (IRF,
see manual for the different ways of giving resolution
parameters). At present, this option works only forconstant wavelength mode.
The FWHM of the Gaussian ( H G ) and Lorentzian( H L ) components of the peak profile have an angulardependence given by:2
H G2 = (U + (1 − ξ ) 2 DST(a D )) tan 2 θ + V tan θ + W +IG
cos 2 θ[Y + F (a Z )]cos θ
If the user provides a file with the IRF, the user should
fix V and W to zero, then the rest of parameters in theabove formula have a meaning in terms of strains( U , a D , X ) or size ( Y , I G , a Z ).

The metric parameters

αi (direct, reciprocal or any

combination) are considered as stochastic variables with aGaussian distribution characterized by the mean

αi andthe variance-covariance matrix Cij . Here we consider theset: {α i } = { A, B , C , D, E , F } .The position of the peaks
is obtained from the average value ofM hkl given by:

M hkl = M ( α i ; hkl ) . The broadening of thereflections is governed by the variance of M hkl :hl S A2
 C ABChk )  AC
 C AD C AE C AF

CAB

CAC

CAD

C AE

S B2
C BC
C BD
C BE
C BF

C BC
S C2
C CD
C CE
C CF

C BD
C CD
S D2
C DE
C DF

C BE
C CE
C DE
S E2
C EF

C AF   h 2  C BF   k 2 
C CF   l 2  
C DF   kl 
C EF   hl  
S F2   hk 

where the non diagonal terms may be written as product ofstandard deviations multiplied by correlation terms:
Cij = Si S j corr (i, j ) . This original formulation can beused with a total control of the correlation terms that must
belong to the interval [-1, 1].

A-strain h k l
43.4585 0 1 2
48.1172 1 0 2
7.1018 1 1 0
5.9724 1 1 1
4.1383 1 1 2
9.7952 0 0 4
4.0162 1 1 379.5271 0 2 087.5578 2 0 0

Nd2NiO4, LT

H L = ( X + ξ DST (a D )) tan θ +The functions

S_400
S_040
S_004
S_220
22.04(78) 17.74(57) 0.016(2) -38.8(1.2)
Lorentzian Parameter: 0.093(2)DST (a D ) and F (a Z ) have different

expressions depending on the particular model used ofstrain and size contribution to broadening. The parameterξ is a mixing coefficient to mimic Lorentzian contribution
to strains.
The anisotropic strain broadening is modeled using aquartic form in reciprocal space. This correspond to aninterpretation of the strains as due to static fluctuations andcorrelations between metric parameters [9].
1
M hkl = 2 = Ah 2 + Bk 2 + Cl 2 + Dkl + Ehl + Fhk = M (αi ; hkl )d hkl
The metric parameters

αi (direct, reciprocal or any

Fig 6: High angle part of the neutron powder diffraction pattern(D2B, ILL) of the low temperature phase of Nd2NiO4 [11]. (top)Comparison of the observed pattern with the calculated patternusing the resolution function of the diffractometer. (bottom)
Observed and calculated pattern using an anisotropic model ofstrains with non-null values given in the panel. A list of apparent
strains (x 10-4), extracted from the microstructure file, for a selected
number of reflections is also given.

When using this formulation the user cannot refine allparameters (up to 21) because some of them contributes tothe same term in the quartic form in reciprocal space,however this allows a better interpretation of the final
results. Taking the appropriate caution one can test
different degrees of correlation between metric parameters.
There are several special formulations, within FullProf, forworking with direct cell parameters instead of using
reciprocal parameters.
Another formulation and a useful notation corresponding
to a grouping of terms was proposed by Stephens [10] who
also included a phenomenological Lorentzian contribution
to the microstrains (the parameter ξ ). The final groupingof terms simplifies to:σ ( M hkl ) = ( h
2

2

k

2

l

2

 h2 
 2
k 
 l2 
kl hl hk ) [C ]   = ∑ SHKLh H k K l L
 kl  H +HKL
K +L =4}
 hl  {  hk The Stephens’ notation can also be used within FullProf.
A maximum of 15 parameters can be refined for thetriclinic case. Whatever the model used for microstrains
the mixing Lorentzian parameter, ξ , may be used. In
FullProf the function

2
DST(a D ) , being a D the set ofparameters Cij or S HKL , is given by: 180  σ ( M hkl )2
DST(a D ) = 10 −8 8Ln2 

2
M hkl
 π 
2

2

Concerning anisotropic size broadening it is possible touse a very general phenomenological model, using theScherrer formula, that considers the size broadening can be
written as a linear combination of spherical harmonics(SPH). At present the anisotropic size is supposed tocontribute to the Lorentzian component of the total Voigt
function. A Gaussian contribution will be introduced using
a mixing parameter similar to that used for anisotropic
strain. The explicit formula for the SPH treatment of size
broadening is the following:

βh =

λ
λ
=
∑ almp ylmp ( Θh , Φ h )Dh cos θ cos θ lmp

where β h is the size contribution to the integral breadth ofreflection h,ylmp ( Θh , Φ h ) are the real sphericalharmonics with normalization as in [12]. The arguments
are the polar angles of the vector h with respect to the
Cartesian crystallographic frame. After refinement of thecoefficients almp the program calculates the apparent size(in angstroms) along each reciprocal lattice vectors if the
IRF is provided in a separate file.
An important type of defects that give rise to size-likepeak broadening is the presence of anti-phase domains andstacking faults. These defects produce selective peakbroadening that cannot be accounted using a small numberof coefficients in a SPH expansion. In fact only a family ofreflections verifying particular rules suffers frombroadening. For such cases there is a number of sizemodels built into FullProf corresponding to particular setsof reflections that are affected from broadening. In figure 7
it is represented the case of Pd3MnD0.8 [13] of structure
similar to Au3Mn and showing the same kind of defects:
anti-phase domains [14]. In figure 8 a portion of the final
microstructural file is shown.
Other models for size broadening in FullProf following
particular rules for each (hkl) are available. Moreover ananisotropic size broadening modeled with a quadratic form
in reciprocal space is also available. The expression
presently used in FullProf is the following:

F (a Z ) = k s d2 (α1h 2 + α2 k 2 + α 3l 2 + α4 kl + α5hl + α 6hk )Fig 7: Portion of the neutron diffraction pattern of Pd3MnD0.8 atroom temperature obtained on 3T2 (LLB, λ = 1.22 Å). On top, thecomparison with the calculated profile using the resolutionfunction of the instrument. Below fit using IsizeModel=-14.
Notice that only the reflections with indices of different parity arestrongly broadened. An isotropic strain, due to the disorder of
deuterium atoms, is also included for all kind of reflections.

An example of anisotropic strain refined using thisformulation is shown in Figure 6, where the neutron
diffraction pattern of the low temperature phase of
Nd2NiO4 is refined using the diffractometer D2B at ILL[11].

where ks is defined as ks=360/π2 × λ 10-3 for the 2θ space
and ks=2/π × Dtt1 10-3 for TOF and Energy space. Simple
crystallite shapes as infinite platelets and needles(IsizeModel = 1, -1 respectively) are also available.
Together with the size broadening models built into
FullProf and described above, there is another way offitting independent size-like parameters for different sets ofreflections. The user may introduce his(her) own rule to besatisfied by the indices of reflections provided the rule canbe written as a linear equality of the form:
n1h + n2k + n3l = n4 n + n5 . Where n is an arbitrary
integer and ni (i = 1,2,...5) are integers given by theuser. A size parameter is associated to each rule (amaximum of nine rules may be given per phase) that may
be refined freely or constrained using the codewords
appropriately.
To access this option in FullProf the value of IsizeModel
should be in the interval [-2,-9]. The absolute value of
IsizeModel corresponds to the number of rules(independent parameters) to be given. If all ni=0 the rule is

! MICRO-STRUCTURAL ANALYSIS FROM FULLPROF (still under development!)! ==================================================================! Pattern No: 1 Phase No:
1 Pd3MnD.8 - CFC... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
! Integral breadths are given in reciprocal lattice units (1/angstroms)x 1000
! Apparent sizes are given in the same units as lambda (angstroms) …
! Apparent strains are given in %% (x 10000) (Strain= 1/2 * beta * d)
! An apparent size equal to 99999 means no size broadening! The following items are output:... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
! The apparent sizes/strains are calculated for each reflection using the formula:!
! App-size (Angstroms) = 1/(Beta-size)! App-strain (%%) = 1/2 (Beta-strain) * d(hkl)!
! (Beta-size) is obtained from the size parameters contributing to the FWHM:!
FWHM^2 (G-size) = Hgz^2 = IG/cos^2(theta)!
FWHM(L-size) = Hlz= ( Y + F(Sz))/cos(theta)!(Beta-strain) is obtained from the strain parameters contributing to the FWHM:!
FWHM^2 (G-strain) = Hgs^2 == (U+[(1-z)DST]^2) tan^2(theta)!
FWHM(L-strain) = Hls= (X+ z DST) tan(theta)!
!
In both cases (H,eta) are calculated from TCH formula and then!
Beta-pV is calculated from:!
!
beta-pV= 0.5*H/( eta/pi+(1.0-eta)/sqrt(pi/Ln2))!
! The standard deviations appearing in the global average apparent size and! strain is calculated using the different reciprocal lattice directions.
! It is a measure of the degree of anisotropy, not of the estimated error
...
betaG
betaL ... App-size App-strainhkl
twtet ...
... 1.4817
11.5859 ...
93.58
41.6395
10017.7931 ...
... 2.0954
11.9584 ...
93.58
41.63951
1
025.2665 ...
... 2.5664
1.5573 ... 99999.00
41.6395
1
1
1
31.0743 ...
... 2.9634
1.7982 ... 99999.00
41.639520036.0343 ...
... 3.3132
12.6973 ...
93.58
41.63952
1
040.4625 ...
... 3.6294
12.8892 ...
93.58
41.6395
2
1
144.5207 ...
... 4.1909
2.5431 ... 99999.00
41.63952
2
051.8786 ...
... 4.4451
13.3842 ...
93.58
41.639530055.2849 ...
... 4.4451
13.3842 ...
93.58
41.6395
2
2
155.2850 ...
... 4.6855
13.5301 ...
93.58
41.6395
3
1
058.5562 ...
... 4.9142
2.9820 ... 99999.00
41.6395
3
1
161.7169 ...
... 5.1327
3.1146 ... 99999.00
41.63952
2
2
64.7864 ...
... 5.3423
13.9286 ...
93.58
41.6395
3
2
067.7802 ...
... 5.5440
14.0510 ...
93.58
41.6395
3
2
170.7114 ...
Fig 8: Portion of the microstructural file (extension mic) corresponding to the fitting of the neutron diffraction pattern in figure 7.

not used. To give a single rule one must put IsizeModel=-2
and put zeros for the last condition. This is needed in order
to avoid the confusion with the case of an infinite needle.
In Figure 10 we give an example using IsizeModel = -2
and in Figure 9 the relevant part of the PCR file is written.
Finally, a general formulation for peak shifts, due todefects or to residual stresses, has also been implemented.
For JSOL≠0, the lines corresponding to shift parameters
are read in the PCR file. Selective shifts can be selected
when IShif <-1. For this option a set of up to ABS(IShif)(≤10) lines can be given. The lines define rules to besatisfied by reflections undergoing shifts with respect tothe theoretical Bragg position due to some kind of defects(stacking and twin

faults for instance). The rules are similar to those of
selective size broadening discussed above. The position of
the reflections satisfying the rules are displaced according
to the expressions:
2θS =2θB + 2 Shift d2 tanθ × 10-2 (2θ space)
TOFS=TOFB − Shift d3 Dtt1 × 10-2 (T.O.F. space)
ES=EB − Shift/(2d) Dtt1 × 10-2 (Energy space)
where the index B stands for the theoretical Bragg positionof the non defective material and Shift is the shiftparameter to be refined. The shift of Bragg reflections may
also be due to external stresses or residual stresses. For
those cases it is more appropriate to use the following
generalized model for shifts.

. . . . . . . . . . . . . . . . . . . . . . . . . . .
! Selective Size-Broadening:! hkl cond.
(n1.h + n2.k + n3.l=n n4 +/- n5)Size-par
0 0 0
0
0
1
2
3
9.61440
0 0 0
0
0
0
0
0
0.00000

Code
661.000
0.000

Fig 9: Portion of the PCR file for IsizeModel = -2 corresponding to the refinement in Figure 10. The first set of zeros below
the text ‘hkl cond.’ is not used at present.

The model is implemented for IShif = 100+NumLaue(with NumLaue the number of the Laue class according to
FullProf manual) , and a set of parameters corresponding
up to quartic form in hkl can be refined. The position of areflection is displaced according to the expressions:
2θS =2θB + 2 Sh d2 tanθ × 10-2 (2θ space)
TOFS=TOFB − Sh d3 Dtt1 × 10-2 (T.O.F. space)
ES=EB − Sh /(2d) Dtt1 × 10-2 (Energy space)
The expression used for calculating the scalar Sh forreflection h is given by:

Sh =

∑

{ H + K + L = 2}

D 2 HKL h H k K l L +∑{ H + K + L = 4}D 4 HKL h H k K l L

The free parameters for this option are the sets D 2 HKL and

D 4 HKL . To refine these parameters the average cellparameters of the non-stressed material should be fixedduring the refinement.
NEAR FUTURE OPTIONS IN FULLPROF.

(4 3 15)(4 1 19)(4 1 17)(4 3 11)(5 2 3), (2 1 23)(4 3 9)(4 1 15)(2 1 21)(4 3 3)

(4 1 13)

Within these notes I have given a flavor of what can bedone using FullProf in some fields of diffraction
applications. The program is in continuous change anddevelopment. Of course the future developments dependon the particular field of Science I’m personally interested:some of the forthcoming options in FullProf reflect mycurrent interests.
- Treatment of polarized neutrons in the single crystal
option. The refinement of coefficients to model the
spin density, in terms of multipoles (linear
combinations of radial functions and sphericalharmonics), from flipping ratio measurements isalready available and under testing but it is not
documented yet.
- Extension of the above formulation for generalelectron density modeling and refinement.
- Size parameters corresponding to particular shape of
crystallites.

Ca2MnO4 (I 41/acd), RT
a=5.187 Å, c=24.123 ÅBroadening: (hkl), l=2n+3

Fig 10: Selective size broadening observed by neutron diffraction attemperature handling(3T2, LLB) forreflections in- roomCompleteof superstructure
crystallographic
Ca2MnO4[15]. (top) Size parameter fixed to zero. (bottom) Single
incommensurate structures. The refinement ofsize parameter according to the rule (hkl), l=2n+3. Indices of mostcommensurate superstructures in terms of Additional
intense Bragg reflections affected by size broadening are also given.

Additional linear and quadratic soft constraints(restrains) defined by the user for arbitrary parameters.
- Complete
handlingofcrystallographic
incommensurate structures. The refinement ofcommensurate
superstructures
in
terms
of
displacements (modulation) functions is alreadyavailable but no totally documented.
- New cost functions in simulated annealing mode:bond valence sums, potentials, etc.
- New description of rigid bodies and moleculargeometry.
A part from these development, a new GUI interface(EdPCR) for working with the PCR file is being preparedby Javier González-Platas and myself. This program will
be useful for beginners to prepare a correct PCR file aswell as for everybody to perform all kind of
crystallographic calculations. The program will be working
in Windows and Linux. We hope to provide a first versionof this program before the summer of this year (2002).
ACKNOWLEDGEMENTS
It is a pleasure to thank here all my colleagues that havecontributed with discussions, writing pieces of code, or arepresently contributing with companion programs to
FullProf: Thierry Roisnel, Javier González-Platas, Aziz
Daoud-Aladine, Carlos Frontera, Vincent Rodriguez andRobert Papoular. I would like to thank many users forgiving me a feedback without which the program could not
be improved.
REFERENCES:[1] Juan Rodríguez-Carvajal and Thierry Roisnel“FullProf.98 and WinPLOTR New Windows 95/NT
Applications for Diffraction. ”, CPD Newsletter 20,
May-August (1998).
[2] Juan Rodríguez-Carvajal and Javier González-Platas“Crystallographic library of Fortran 95 modules”(unpublished)[3] Javier González-Platas and Juan Rodríguez-Carvajal“GFourier: a Windows/Linux program to calculate anddisplay Fourier maps ” (unpublished)[4] M. Kara, K. Kurki-Suonio, Acta Cryst 37, 201 (1981)[5] Juan Rodríguez-Carvajal, Materials Science Forum(2001) ; see also Proceedings of the XVIII Conference
on Applied Crystallography, Ed. Henryk Morawiec andDanuta Stróz, World Scientific, London 2001, pp 30-36[6] Thompson, Cox, Hastings, J. Appl. Cryst. 20, 79 (1987)[7] L.W. Finger, J. Appl. Cryst. 31, 111 (1998)[8] Microstructure Analysis from Diffraction, edited by R.
L. Snyder, H. J. Bunge, and J. Fiala, International
Union of Crystallography, 1999.
[9] J. Rodríguez-Carvajal, M.T. Fernández-Díaz and J.L.
Martínez, J. Phys: Condensed Matter 3, 3215 (1991)[10] P. W. Stephens, J. Appl. Cryst. 32, 281 (1999)[11] M. T. Fernández-Díaz, M. Medarde and J. RodríguezCarvajal (unpublished).
[12] M. Jarvinen, J. Appl. Cryst. 26, 527 (1993)[13] P.Onnerud, Y. Andersson, R. Tellgren, P. Norblad, F.
Bourée, G. André, Solid State Comm. 101, 433 (1997)[14] B.E. Warren, “X-ray Diffraction”, Dover Publications,Inc., New York, 1990.
[15] C. Autret et al. (unpublished).

Rietveld Refinement and Beyond
D. E. Cox
Physics Department (Emeritus), Brookhaven National
Laboratory, Upton, USA
In the past few years, there has been a distinct trend awayfrom the “classical” applications of the Rietveld techniquetowards structure solution and determination. By“classical”, I mean the types of problem typicallyencountered in traditional areas of materials science suchas superconductors, magnetic systems, ferroelectrics andbattery materials, in which the structure determination partof the project is frequently straightforward or even trivial,
but the precise details of the refinement are all-important.
It is clear that this trend has been accentuated both by thedevelopment of very elegant real-space methods ofstructure solution and by the availability of more userfriendly and sophisticated software for traditional methodsof structure solution, especially as applied to small (andnot-so-small) organic molecules, as described in the July
issue of the CPD Newsletter. Another powerful driving
force in my opinion has been the superb quality of the datathat can be collected at second- and third-generationsynchrotron sources (although this is perhaps a more
controversial viewpoint not shared by everyone), but
unfortunately, there still appears to be some reluctancewithin the powder diffraction community to exploit thesesources.
In the present article, I will argue that Rietveld
refinement still has an important role to play in materials
science, but with a number of caveats which werepreviously not so apparent in the analysis of laboratory xray and neutron data sets, but which can no longer beignored under the harsh glare of a high-resolution
synchrotron x-ray experiment. I will focus on some ofthese caveats and possible pitfalls, especially in the context
of some recent diffraction studies of the piezoelectric
perovskite-type system PbZr1-xTixO3 (commonly known as
PZT) carried out by my colleagues Beatriz Noheda and
Gen Shirane at Brookhaven, together with a number ofcollaborators at other institutions. PZT is well-known to
exhibit very desirable piezoelectric properties under anapplied electric field and is the backbone of many
commercial electromechanical devices. For almost four
decades, these properties have been associated with thecoexistence of rhombohedral and tetragonal phases in thevicinity of the so-called “morphotropic phase boundary”(an almost vertical line on the temperature-composition
phase diagram at x ˜ 0.48 separating regions withrhombohedral and tetragonal symmetry, usually called theMPB), as described in numerous laboratory x-ray andneutron powder diffraction studies. However, a surprise
was in store, for in 1999 a high-resolution synchrotron xray study of this composition revealed the presence of anew phase with a slightly-distorted monoclinic
structure[1]. Subsequent Rietveld refinement showed thatthe polar axis in the new phase was rotated away from thetetragonal [001] axis towards the rhombohedral [111] axis,
and that the monoclinic structure could therefore beviewed microscopically as a “bridge” between these twohigher-symmetry structures[2]. Since then there have been
numerous experimental and theoretical studies of PZT andrelated systems which have provided much new insight
into the relationship between this and other lowersymmetry phases and their electrical properties.

The optimization of physical properties in temperaturecomposition phase space is of course a very common
objective in materials science, but as in the case of PZT,
the problems of pseudosymmetry and phase coexistence
are not always recognized, and then Rietveld refinement
can at best give only some kind of average structure and atworst erroneous results. How can such pitfalls best be
avoided? Clearly, high-quality samples and high-resolution
synchrotron data are an excellent starting point. If, as isoften advantageous, Debye-Scherrer diffraction geometry
with a capillary specimen is chosen, it is important not todegrade the sample by excessive grinding, which can resultin broadened peaks. To this end we routinely adopt theprocedure of lightly crushing ceramic samples (or evensmall single crystals) and only using the fraction retained
between 325 and 400 mesh sieves - large boulders bynormal powder diffraction standards!
In an ideal world, a small distortion would be uniquely
revealed by a definite splitting of certain types of peaks,
but unfortunately the situation is often complicated byanisotropic peak broadening, which is discussed in moredetail by Peter Stephens in another article in this issue.
Such anisotropic broadening has a number of possible
origins; in mixed systems one common cause is thesensitivity of some of the lattice parameters to the presenceof small long-range fluctuations in composition. Under
these circumstances, we have found that fits to selected
clumps of peaks (preferably with unconstrained individual
peak widths and mixing parameters) prior to Rietveld
refinement is the best way to unequivocally establish thepresence of a lower-symmetry distortion and/or phasecoexistence. Although pattern-matching techniques(refinement without a structural model) are frequently
employed for this purpose, it is important to remember that
if anisotropic peak broadening is neglected, the choice of alower-symmetry cell will very likely result in an improved
fit, but not necessarily any better than the fit obtained witha higher-symmetry cell and a generalized model ofanisotropic broadening.
It frequently happens in materials science studies that one
is confronted with the problem of discriminating between
less- and more-constrained structural models, involving
pseudosymmetry, non-stoichiometry, mixed cation
distribution and highly-anisotropic temperature factors
related to static or dynamic cation disorder, to name a few.
In such a situation, is it possible to make any kind of
objective choice between the models? This is not a trivial
question, since the existence of subtle features of this sort
may have an important bearing on understanding thephysical properties, but it is one that statisticians appear
reluctant to address. For want of anything better, one canuse to the Hamilton significance tests [3]. Of course, theserequire an estimate of the number of independent
observations (integrated intensities or F2 ’s), but several
reasonable algorithms have been proposed in the literature(for example, the number of peaks or clumps of peaks
separated by = 0.5 FWHM). In my experience, these tests
generally work quite well if applied conservatively, even if
they do not meet with the approval of the statisticians. This
type of approach also allows a more realistic estimate ofstandard errors [4], but that is another story.
Our ability to extract accurate structural information frompowder data is now further enhanced by another powerfuland elegant tool, namely the combination of Rietveld
refinement with Maximum Entropy Methods (MEM),

which has been exploited very effectively in the past few
years by Masaki Takata, Matt Sakata and colleagues at
Nagoya University. This is an iterative procedure in which
the features observed in the MEM electron density
distribution at each step are incorporated into an improved
structural model for the next stage of Rietveld refinement
until the final distribution is compatible with the structuralmodel. The application of this technique to materials
science is described for a number of systems in a recent
review article by Takata et al.[5], one beautiful example
being the direct observation of orbital order in the
manganite compound NdSr2Mn2O7. This procedure avoids
the guesswork involved in fine-tuning the structural modelin an unbiased way, and hopefully will become standardpractice in the future.
It is interesting to recall that Rietveld refinement was
originally developed for structure analysis based on
neutron powder data, and the powder diffraction
community has a long and distinguished track-record ofusing neutron facilities for materials science studies. With
new synchrotron sources being built or planned around theworld, there are rapidly expanding opportunities to exploit
high-resolution synchrotron techniques in the same way.
At the same time, as outlined above, there will be many
new challenges along the way.
REFERENCES[1] B. Noheda, D. E. Cox, G. Shirane, J. A. Gonzalo, L. E.
Cross and S-E. Park, Appl. Phys. Lett. 74, 2059 (1999).
[2] B. Noheda, J. A. Gonzalo, L. E. Cross, R. Guo, S-E.
Park, D. E. Cox and G. Shirane, Phys. Rev. B 61,
8687 (2000).
[3] W. C. Hamilton, Acta Cryst. 18, 502 (1965).
[4] D. E. Cox and R. J. Papoular, Mater. Science Forum,
228-231, 233 (1996).
[5] M. Takata, E. Nishibori and M. Sakat, Z. Kristallogr.
216, 71 (2001).

0

Accuracy In X-ray Powder Diffraction:
A Comparison of Quantitative Methods

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Fig. 1 Experimental design for IUCr-CPD round robin
Sample 1 suite.
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INTRODUCTION
A comparison of commonly used methods ofquantitative phase analysis (QPA) using powder X-ray
diffraction (XRD) methods has been carried out. The
sample mixture used for this study was that distributed by
the IUCr-CPD as sample 1 in its recent round robin on
QPA via diffraction methods1. Figure 1 shows theexperimental design of the eight mixtures comprisingsample 1. Figures 2 and 3 show the results returned fromthe round robin for CPD-supplied and participantcollected data respectively.
QUANTITATIVE METHODS USED
X-ray Fluorescence (XRF) - included as a “standard”
method which in the case of these samples should be themost accurate and reproducible.
Reference Intensity Ratio2 (RIR) - single peak (RIR1) ormulti-peak (RIR2) method where RIR (I/Ic) is defined as
the ratio of the strongest peak of any phase j to the90

20

Nicola V.Y. Scarlett & Ian C. Madsen
CSIRO Minerals, Bayview Ave, Clayton, VIC 3168,
Australia
nicola.scarlett@csiro.au
The following paper is the summary of a poster
presentation made at “Accuracy in Powder Diffraction
III” (APD III), National Institute of Standards andTechnology, Gaithersburg, Maryland, USA in April 2001.
It is a detailed comparison of different quantitative phaseanalysis (QPA) techniques using the IUCr-CPD QPA
round robin sample 1 as the test material. This study wasprompted by the large spread of returns received from theround robin participants which lead to uncertainty inknowing whether the variability was due to the analyticalmethods or their application. In this work, different
analytical methods were tested by the same operators
using the same data sets thus reducing the number ofvariables for consideration.

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Fig 2 Analysis results - IUCr round robin, CPD-supplied
data. Note the spread of results.

strongest corundum peak (113) in a 1:1 mixture (byweight). In this instance the matrix flushing method of
Chung3 has been employed thus producing a result
normalised to 100wt%.
Iterative Least Squares (ILS) - single peak (Zevin1) ormulti-peak (Zevin2) method where a series ofsimultaneous equations based upon the basic quantitative
phase analysis equation (Eqn 1) are derived using all
samples in the suite. In this instance, the modification of
Zevin2 has been used where the constant term K
incorporates the mass absorption coefficient of the sample(µm) and the density of the phase and µm is iteratively
calculated from the concentrations using an MS-EXCEL
spreadsheet.

ck = K k I ik
Eqn 1: Quantitative phase analysis equation of Knudsen7
where ck is the concentration of phase k, Kk is a constantand Iik is the intensity of the ith peak of phase k.
Mean Normalised Intensity4 (MNI) - multi peak method
similar to RIR where the mean normalised intensity of all
peaks for a particular phase is used in place of theintensity of the strongest peak.
Rietveld Refinement - Whole pattern method where therefined scale factor of each phase is related to phase
concentration via Eqn 2. This study used two software
packages: Koalariet6 (Rietveld1) and SR55 (Rietveld2).

s ( ZMV ) k
ck = k∑ si ( ZMV )i
Eqn 2: Rietveld equation where ck is the concentration ofphase k, s is the phase dependent, refinable Rietveld scale
factor and ZMV are the number, mass and volume
respectively of the formula units in each phase5.
RESULTS AND DISCUSSION
Results have been assessed according to a statistic basedon the Kullback-Leibler distance (KLD)8. This value isweighted according to the concentration of a phase (Eqn 3)
and may be summed to provide a single numericalassessment of the accuracy of a determination (Eqn 4).
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Eqn 3: Kullback-Leibler distance weighted for phase
concentration.

AKLDsum = AKLDcorundum + AKLD fluorite + AKLDzincite
Eqn 4: Sum of absolute values of Kullback-Leibler
distance

Uncertainty =2 * SD of AKLDN

Eqn 5: Calculation of the uncertainty of the AKLD values
where SD is the standard deviation of the group and N is
the number of values in the group.
Table 1 shows the assessment of the analytical methods
considered here via the calculation of AKLDsum values.
There is little significant difference between any of themethods and all returned a very low average AKLDsum
value representing accurate analyses. This is borne out in
Figure 4 which shows graphically the results of all
analyses performed using all methods and should becompared with the spread of returns from the IUCr-CPD
round robin (Figures 2 and 3). It is noteworthy that eachgroup in Figure 4 represents 24 separate analyses (8analytical methods, three replicates of each).

AKLDsum
Authors
IUCr Round Robin
Participants
CPD
Participant
Data
Data
0.008(1)0.008(1)0.008(1)
XRF*
0.016(3)MNI
0.010(3)0.044(9)0.044(4)Rietveld 1
0.012(4)Rietveld 2
0.009(2)0.046(320.089(19)RIR 1)
0.011(2)RIR 20.016(3)Zevin 10.015(3)Zevin 20.044(9)0.050(2)All Methods 0.013(1)Analysis
Method

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 wt %True KLD = 0.01× wt %True × ln wt % Measured 

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Absolute values of this figure (AKLD) have been used toprovide a general estimate of the magnitude of the error.
Averages of these AKLDsum values provide an estimate of
the accuracy of analysis across a particular group, which isin this case, analytical method. Small values of AKLDsum
represent the most accurate analyses. To assess thevariation of AKLD within a group, an approximate estimateof the 95% confidence limits can be obtained by first
determining the standard deviation (SD) of all values of
AKLD in the group and calculating the uncertainty
according to Eqn 5. The significance of differences
between groups is based on their combined uncertainties.

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Fig. 3 Analysis results - IUCr round robin, participantcollected data. Note that the spread of results isgreater than for the CPD-supplied data.

Table 1. Assessmentofanalyticalmethods
via
measurement of AKLDsum.
*XRF value not included in calculation of “All Methods”
AKLDsum

REFERENCES
0
1a
1b
1c
1d
1e
1f
1g
1h

10

100
90

20

80
70

Co
run
du
m

40

60

50

%)
(wt
cite
Zin

(wt
%)

30

50

60

40

70

30

80

20

90

10

100
0

0
10

20

30

40

50

60

70

80

90

100

Fluorite (wt%)

Fig 4: Analytical results - authors.

CONCLUSION
The errors reported in the IUCr-CPD round robin returns
for sample 1 are largely operator induced. This study has
shown that, for a simple crystalline system such as thisone, many common methods of quantitative phase analysis
using XRD are adequate. Differences in applicability ofthese methods may arise in more complex analyticalsystems where problems such as preferred orientation,
microabsorption and presence of amorphous material may
occur.

Internet Available Rietveld Software
Lachlan M. D. Cranswick
Collaborative Computational Project No 14 (CCP14)
for Single Crystal and Powder Diffraction
CCP14 - School of Crystallography,
Birkbeck College,
Malet Street, Bloomsbury,
WC1E 7HX, London, UK
Tel: (+44) 020 7631 6849
Fax: (+44) 020 7631 6803
E-mail: l.m.d.cranswick@dl.ac.uk
WWW: http://www.ccp14.ac.uk http://ccp14.sims.nrc.ca - http://ccp14.semo.edu
There exists at present a wide genetic diversity of
Rietveld programs expressing a range of ideas andapproaches. Many of these software packages are alsoavailable via the Internet for the benefit of the scientificcommunity. When up against a new structure refinementof powder diffraction data, it can be worth while exploring
the available Rietveld programs to determine which may
be the most appropriate to use with particular problems.
Most can be immediately downloaded, tested and run. The
following represents a non-comprehensive list of what canbe found on the Internet, mentioning some of thefunctionality that is available (to exhaustively mention the

1. Madsen, I.C., Scarlett, N.V.Y., Cranswick, L.M.D. and
Lwin, T. (2001) “Outcomes of the International Unionof Crystallography Commission on Powder Diffraction
Round Robin on Quantitative Phase Analysis: Samples
1A to 1H” J. Appl. Cryst. (2001), 34, 409-426.
2. Zevin, L.S. and Kimmel, G. (1995) “Quantitative X-ray
Diffractometry” Springer-Verlag New York, Inc.
3. Chung, F.H. (1974) “Quantitative Interpretation of Xray Diffraction Patterns of Mixtures II. Adiabatic
Principle of X-ray Diffraction Analysis of Mixtures” J.
Appl. Cryst. 7, 526.
4. Li, De Y. and O’Connor, B.H. (1998) “MeanNormalized-Intensity (MNI) Method For X-ray Powder
Diffraction Phase Composition Analysis” Material
Science Forum Vol278-281, 57-62 Trans-Tech
Publications Ltd.
5. Hill R.J. and Howard C.J. (1986) “A Computer
Programme for Rietveld Analysis of Fixed Wavelength
X-ray and Neutron Powder Diffraction Patterns”,
AAEC (now ANSTO) Report AAEC/M112.
6. Coelho A.A., Madsen I.C. and Cheary R.W. (1997),“A New Rietveld Refinement Program Using a
Fundamental Parameters Approach to SynthesizingLine Profiles”, Abstract D1-PM2, Proceedings of the20th Conference of the Society of Crystallographers inAustralia, April 2nd -5th, Queenstown, New Zealand.
7. Knudsen, T. (1981) “Quantitative X-ray Diffraction
Analysis With Qualitative Control Of Calibration
Samples”, X-ray Spectrometry, 10(2), 54-56.
8. Kullback, S. (1968), “Information Theory andStatistics”, Dover Publications, 1-11.
entire functionality of a single Rietveld program could takequite a few pages). Nearly all the following software canbe obtained via the CCP14 mirrors viewable at
http://www.ccp14.ac.uk/mirror/. Suggestions on additions,
missing information, corrections and elaboration on thefollowing would be appreciated by sending an E_mail tothe author so it can be included in the next edition of the
CPD newsletter.
Rietveld Code of Historical Interest
Some Rietveld codes of historical interest are available
on the internet. This includes the original Hugo Rietveld
report containing Algol source code (H. M. Rietveld, “An
ALGOL Program for the Refinement of Nuclear andMagnetic Structures by the Profile Method by H. M.
Rietveld”, Reactor Centrum Nederland, April 1969; RCN104.)at
http://www.ccp14.ac.uk/ccp/web-mirrors/hugorietveld/riet-report/. This webpage also links to online versions of the seminal Rietveld Method papers.
Another example is the Hugo Rietveld & Alan Hewat
Fortran source code for Rietveld/Profile Refinement
viewable at http://www.ccp14.ac.uk/ccp/web-mirrors/hewat-rietveld/.
A range of Rietveld programs available via the internet
BGMN
Fundamental parameters Rietveld for structurerefinement, size-strain and quantitative analysis

Contact: Joerg Bergmann
Email: support@bgmn.de
WWW: http://www.bgmn.de
References: J. Bergmann, R. Kleeberg, and T. Taut “A
new structure refinement and quantitative phase analysis
method basing on predetermined true peak profiles” Z. f.
Kristallographie, Supplement issue No. 8, Europ. Cryst.
Meeting 15 (1994), Book of Abstracts p. 580
While a Graphical User Interface (GUI) version of
BGMN is commercially available from Siefert, academics
and student can download a free non-GUI version from the
BGMN website which uses an ASCII control file. BGMN
makes use of “fundamental parameters”; high stability
algorithms in modeling the diffraction profile; and a macro
based equation editor. This makes BGMN effective inobtaining accurate size-strain, structural and quantitative
analysis results.

Fig 1: BGMN quantitative analysis fit to reference sample
Metashale Böhlscheiben, “Bergmann, J., Kleeberg,
R.,Taut, T., Haase, A., 1997: Quantitative Phase
Analysis Using a New Rietveld Algorithm Assisted by Improved Stability and Convergence
Behavior. Adv. X-Ray Analysis 40 (1997).”
DBWS
Rietveld Refinement, quantitative phase analysis
and size-strain analysis.
OS: DOS/MS-Windows, SUN Solaris and Linux
Contact: Ray Young
Email: r.young@physics.gatech.edu
WWW:http://www.physics.gatech.edu/downloads/young/DBWS.html
References: R. A. Young, A. Sakthivel, T. S. Moss and C.
O. Paiva-Santos, “DBWS-9411 - an upgrade of the DBWS
programs for Rietveld Refinement with PC and mainframe
computers”, J. Appl. Cryst., Vol. 28, 366-7; 1995
DBWSTOOL
Graphical User Interface for creating and controling
DBWS input files
OS: MS-Windows
Contact: Lucas Bleicher
Email: sasaki@fisica.ufc.br
WWW: http://www.fisica.ufc.br/raiosx/DBWS.htm
Download FTP: http://www.ccp14.ac.uk/ccp/ccp14/ftpmirror/dbwsgui/pub/
References: L. Bleicher, J. M. Sasaki and C. O. Paiva
Santos. “Development of a graphical interface for the

Rietveld refinement program DBWS” (2000). J. Appl.
Cryst. 33, 1189.
DBWS is a Rietveld program whose source code has
spawned a number of variants (Fullprof, LHPM, SR5,
Riet7, Rietica, etc), but still has a free-standing active
existence. Applications of DBWS include structurerefinement of colossal magnetoresistance materials,
thermoelectrics and negative thermal expansion ceramics,
quantitative analysis and crystallite size and microstrain
analysis. While DBWS is normally controlled via an
ASCII input file, the recently written DBWSTool can act
as a Graphical User Interface (GUI) for setting up a
starting ASCII input file and controlling the refinement.

Fig 2: Starting screen for DBWSTools; a graphical userinterface for DBWS Rietveld.
Fullprof
Single crystal and powder diffraction refinement
software
OS: MS-Windows, DOS, SUN Solaris and Linux
Contact: Juan Rodriguez-Carvajal
Email: juan@bali.saclay.cea.fr
WWW: http://www-llb.cea.fr/fullweb/powder.htm
Download FTP:
ftp://charybde.saclay.cea.fr/pub/divers/fullprof.2k/
References: J. Rodriguez-Carvajal, Abstr. 15th Conf. Int.
Union Crystallogr. (Toulouse, France) 1990, p. 127,
Satellite Meeting on Powder Diffraction.
The Fullprof Rietveld software can perform a variety ofrefinement types, including combined X-ray / Neutron;
TOF neutron; fixed angle INEL PSD data, incommensurate
refinement, magnetic refinement. Fullprof is normallycontrolled via an ASCII input file and links to a number ofutility programs such as Winplotr utility software (byThierry Roisnel and Juan Rodriguez-Carvajal), JfullProf
GUI for Fullprof (by Alain Bouvet) and GFOUR Fouriersoftware (by Javier Gonzalez-Platas and Juan RodriguezCarvajal). As Fullprof is the subject of a separate article inthis issue of the CPD newsletter, the following willconcentrate on the Winplotr software provided with
Fullprof.
Winplotr for MS-Windows by Thierry Roisnel and Juan
Rodriguez-Carvajal provides a wide range of functionality.
This includes the ability to plot Fullprof PRF, Jana2000
PRF, Rietian2000 PAT and Debvin GRA Rietveld plot
files; not only in 2-theta/TOF space, but also Q (Å-1), d(Å), sinTheta/Lambda and “s” (= 1/d). Winplotr will open
Fullprof, GSAS, CPI and other raw data file formats. Data
analysis includes background selection, peak find (manualand automatic), peak profiling, integration, summation,
averaging, background subtraction and passing peak
positions to various indexing programs included with theWinplotr distribution (WinIto, WinDicvol, WinTreor andsupercel). At the termination of a successful powderindexing session, Winplotr can also create starting Fullprof
PCR files.

Fig 3: Winplotr (supplied with Fullprof) a) viewing a
Rietveld plot file while also showing the variety of
raw data file formats in can open; and b)
displaying diffraction patterns in a pseudo 3D plot
as described in the Winplotr tutorials at :http://www-llb.cea.fr/fullweb/winplotr/wpl_demo.htm.
GSAS
Single crystal and powder diffraction refinement
software
OS: MS-Windows, SGI IRIX and Linux
Contact: Bob Von Dreele and Alan Larson
Email: vondreele@lanl.gov
Download FTP: ftp://ftp.lanl.gov/public/gsas/
References: A.C. Larson and R.B. Von Dreele, "General
Structure Analysis System (GSAS)", Los Alamos National
Laboratory Report LAUR 86-748 (1994).
The GSAS structure refinement suite is controlled by amenu based system, and can handle a range of structures
including proteins. GSAS has a large number of restraint
types; the ability to refine on single crystal and powder
diffraction data. Combined refinement of X-ray / Neutron
data can be performed, including TOF Neutron and Energy
Dispersive X-ray data. A large number of utilities plug
into GSAS or can make use of GSAS files and a list ofthese is available via the CCP14 website at
http://www.ccp14.ac.uk/solution/gsas/. As GSAS is the
subject of a separate article in this issue of the CPD
newsletter, the following will concentrate on Brian Toby’s
EXPGUI software, which is a Graphical User Interface(GUI) for GSAS running on UNIX and Windows.

EXPGUI
Graphical User Interface for GSAS running on Windows
and UNIX
OS: MS-Windows, SGI IRIX and Linux
Contact: Brian Toby
Email: Brian.Toby@nist.gov
WWW:
http://www.ncnr.nist.gov/programs/crystallography/softwar
e/expgui/References: B. H. Toby, EXPGUI, a graphical userinterface for GSAS, J. Appl. Cryst. (2001). 34, 210-213.
EXPGUI allows people familiar with Windows stylegraphical user interfaces to quickly and intuitively start
using GSAS. EXPGUI also has extra functionality notavailable in the standard GSAS package. This includes theability to graphically select a manual background(BKGEDIT) and fit it to a Chebyshev function; graphically
exclude regions (EXCLEDT); and the display of“cumulative chi squared plots” [W.I.F. David, "Beyond
least-squares analysis in profile refinement"; Accuracy inPowder Diffraction-III, 2001]. The latest versions also
include the ability to set up dummy histograms andenable/disable histograms (diffraction patterns).

Fig 4: The new BKGEDT function in Brian Toby’s
EXPGUI for manually defining the background(triangles) which can then be fitted by a
Chebyshev function and saved in the GSAS EXP
file. The poor difference curve is from theprevious “refined” background during Le Bailfitting.
Jana2000Single crystal and powder diffraction refinement ofStandard, Modulated and Composite Structures
OS: Windows and UNIX (IRIX, Linux, etc)
Contact: Vaclav Petricek & Michal Dusek
Email: petricek@fzu.cz or dusek@fzu.cz
WWW: http://www-xray.fzu.cz/jana/jana.html

FTP Download: ftp://ftp.fzu.cz/pub/cryst/jana2000
References: Dusek, M., Petricek, V., Wunschel, M.,
Dinnebier, R.E. and Smaalen, S. van (2001),
J.Appl.Cryst.34, 398-404, Refinement of modulated
structures against X-ray powder diffraction data with
Jana2000 and Petricek,V. & Dusek,M.(2000). The
crystallographic computing system JANA2000. Institute ofPhysics, Praha, Czech Republic.
A recent change in the Jana single crystal suite is theability to now refine on powder diffraction data via an
extension to the Jana Graphical User Interface (GUI). Thiswas made possible using source code and implementation
details provided by Bob von Dreele. As well as reading its
own data format, Jana2000 can also read GSAS andRIETAN data file formats. In the latest beta version,
Jana2000 can handle multiple phases. Other features
include Le Bail fitting, modelling peak asymmetry via theFinger, Cox, Jephcoat method; and anisotropic peakbroadening via the Stephens method (J. Appl. Cryst. 32,
281 (1999)). As information on powder refinement has notmade it into the Jana manual, there is a web tutorial at
http://www-xray.fzu.cz/jana/Jana2000/powders.html;
again with mirrors via the CCP14 websites:
UK: http://www.ccp14.ac.uk/ccp/webmirrors/jana/jana/Jana2000/powders.html
Canada:http://ccp14.sims.nrc.ca/ccp/webmirrors/jana/jana/Jana2000/powders.html
US:
http://ccp14.semo.edu/ccp/webmirrors/jana/jana/Jana2000/powders.html

Fig 5: Fourier contour map viewing as part of Jana 2000.
Powder refined structures have access to all the
relevant facilities of the Jana2000 software;
including Fourier map generation and viewing;
charge density analysis; etc.
MAUD for Java
GPL’d materials science Rietveld for structurerefinement, crystallite size-strain-shape, polefigure and quantitative analysis.
OS: Any Java enabled platform (Mac, Windows, UNIX)as well as GPL’d source code
Contact: Luca Lutterotti
Email: Luca.Lutterotti@ing.unitn.it
WWW: http://www.ing.unitn.it/~luttero/maud/
References: L. Lutterotti, S. Matthies and H. -R. Wenk,“MAUD (Material Analysis Using Diffraction): a user
friendly Java program for Rietveld Texture Analysis andmore.", Proceeding of the Twelfth International Conference
on Textures of Materials (ICOTOM-12), edited by Szpunar
J. A., August 9-13, 1999, Montreal, Canada. Vol. 2, 1599.
MAUD (Material Analysis Using Diffraction) for Java is
optimised for materials analysis and runs controlled by aGraphical User Interface (GUI). Capabilities include
quantitative analysis (with the new ability to import an
HKL file if the structure is lacking); size-strain-shapeanalysis; pole-figure analysis, and other materials analysis.
New developments in MAUD are also being implemented
to assist in structure solution from powder diffraction using
genetic algorithms. Web tutorials are available via the
MAUD webpage at http://www.ing.unitn.it/~luttero/maud/tutorial/, showing how techniques such as
quantitative analysis; digitising a diffraction image; andtexture analysis from traditional pole figures. MAUD is
distributed under the GNU Public Licence such that its
source code can be freely modified. For information on the
GNU
GeneralPublicLicense,refer
to
http://www.gnu.org/copyleft/gpl.html.

Fig 6: Screen images of MAUD for Java Rietveld
software in action while performing texture / pole
figure analysis as described in the tutorial at
http://www.ing.unitn.it/~luttero/maud/tutorial/OD
FfromPF/
Prodd
Powder diffraction refinement with the source code
bundled up in the CCSL (Cambridge Crystallography
Subroutine Library)
OS: DOS executable and source code available from theauthors
Contact: Jon Wright and Bruce Forsyth
Email: wright@esrf.fr

WWW:
http://www.ccp14.ac.uk/ccp/web-mirrors/prodd/~jpw22/
CCSL WWW: http://www.ill.fr/dif/ccsl/
References: J P Wright & J B Forsyth “Profile
Refinement of Diffraction Data using the Cambridge
Crystallographic Subroutine Library (CCSL)”; Rutherford
Appleton Laboratory Report RAL-TR-2000-012; Version
1.0; May 2000.
Prodd is a new “hackers” Rietveld for those who may
have structure refinement problems that are not doable inexisting Rietveld binaries (thus requiring custom coding).
An extra advantage is that Prodd is based around the CCSL
(Cambridge Crystallography Subroutine Library). Thoughto learn the rest of the CCSL would result in a higher
learning curve. Prodd is controlled by editing an ASCII fileand supports time of flight and constant wavelength
neutron data as well as synchrotron X-ray; but not (atpresent) laboratory X-ray data.

Fig 7: Two fits for FeAsO4 on POLARIS (3 detectorbanks, from J.P.Wright, PhD Thesis, Univ. ofCambridge). One fit has magnetic peaks, the other
does not. Description of the magnetic structure inin Forsyth JB, Wright JP, Marcos MD, Attfield JP,
Wilkinson C; "Helimagnetic order in ferricarsenate, FeAsO4"; Journal of Physics-Condensed
Matter, 11 (6): 1473-1478 Feb 15 1999.
ProfilRietveld that automatically handles atomic andanisotropic symmetry; and with restraints suitable forrefinement of molecular compounds.
OS: DOS/Windows and VMS
Contact: Jeremy Cockcroft
Email: cockcroft@gordon.cryst.bbk.ac.uk
WWW: http://img.cryst.bbk.ac.uk/www/cockcroft/profil.htm
FTP Download: ftp://img.cryst.bbk.ac.uk/pdpl/
References: J. K. Cockcroft & A. N. Fitch. “The solid
phases of sulphur hexafluoride by powder neutron
diffraction.” Zeitschrift fur Kristallographie 1988, 184,123-145.

Profil is controlled by an ASCII input file, and hasfeatures relevant to complex Rietveld refinement;
including the refinement of molecular compounds.
Features include automatic constraints with respect toatoms on special positions and swapping between isotropic
and anisotropic thermal formats. Available bond restraints
include bond angle, bond length and “same” restraints.
There is a newly added “multiple site chemicalcomposition restraint” which, like the similar GSAS “totalchemistry restraint”, can be used as a charge balance
restraint. Spacegroups are defined by symmetry operators,
which Profil interprets and outputs the spacegroup symbol
to the user (or an error if the symmetry operators do notdescribe a complete set). Thus Profil can handle quite
complex (and useful) commensurate non-standard cell
types relevant to materials science (e.g., F2/d monoclinic).
(Refer: J. K. Cockcroft, A. Simon, H. Borrmann, & A.
Obeymeyer. “The crystal structures of the low-temperature
modifications of deuterium iodide - A neutron study.”;
European Journal of Solid State Inorganic Chemistry 1988,
25, 471-481.).

Fig 8: Structure of SF6. The Profil refinement involved
making liberal use of the “same” bond-length
restraint (required due to pseudo-symmetry). Cited in
J. K. Cockcroft & A. N. Fitch. “The solid phases ofsulphur hexafluoride by powder neutron diffraction.”Zeitschrift fur Kristallographie 1988, 184, 123-145.
RietanGPL’d powder diffraction refinement with MEM-based
whole-pattern fitting
OS: Mac OS, MS-Windows and GPL’d source code
Contact: Fujio Izumi
Email: IZUMI.Fujio@nims.go.jp
WWW:
http://homepage.mac.com/fujioizumi/rietan/angle_dispersi
ve/angle_dispersive.html
References: F. Izumi and T. Ikeda, Mater. Sci. Forum,
321-324 (2000) 198-203 and F. Izumi, S. Kumazawa, T.
Ikeda, W.-Z. Hu, A. Yamamoto, and K. Oikawa, Mater.Sci.
Forum, 371-381 (2001) 59-64.
As one of its features, Rietan2000 is presently the only
Rietveld program which implements MEM (maximumentropy method)-based whole-pattern fitting; making it
possible to represent a crystal structure withelectron/nuclear densities. It is controlled by an ASCIIinput file and is provided as executables and source code
under the GNU Public Licence. For information on the
GNU
GeneralPublicLicense,refer
to
http://www.gnu.org/copyleft/gpl.html. As Rietan2000 is
the subject of a separate article in this issue of the CPD
newsletter, its features will not be elaborated here.

Fig 9: Example Rietveld plot and structure refined with
Rietan2000.
RieticaSequel to the LHPM Rietveld with a complete graphicaluser interface
OS: MS-Windows
Contact: Brett Hunter
Email: bah@ansto.gov.au
WWW: http://www.rietica.org
FTP
Download:
ftp://ftp.ansto.gov.au/pub/physics/neutron/rietveld/Rietica_
LHPM95/
References: Hunter B. (1998) Rietica - A visual Rietveld
program, International Union of Crystallography
Commission on Powder Diffraction Newsletter No. 20,(Summer) http://www.rietica.org
Rietica is the sequel to the LHPM Rietveld software andhas a complete Graphical User Interface (while stillretaining the traditional ability to edit an ASCII controlfile). Combined refinement can be performed on X-ray
and neutron data (constant wavelength and TOF) as well aseasy point and click mass Le Bail fitting. As well as theability to import GSAS EXP and Fullprof PCR refinement
files, it also includes an implementation of I. D. Brown’s
method for bond-valence calculation that can be used tocheck refined structures at the click of a menu option.

WinMprof
Rietveld refinement with bond restraints (including the“same” restraint) and features suitable for restrainedrefinement of molecular structures.
OS: MS-Windows
Contact: Alain Jouanneaux
Email: jouanneaux@univ-lemans.fr
WWW: http://lpec.univ-lemans.fr/WinMProf/
References: A. Jouanneaux, X. Le Gonidec and A.N.
Fitch "WinMProf : a visual Rietveld software" EPDIC7 :Materials Science Forum vols 378-381 (2001), pp 112-117.
WinMprof for MS-Windows includes such functionality
as: Le Bail fitting; peak asymmetry correction using theFinger, Cox, Jephcoat method ((1994) J. Appl. Cryst. 27,892) or the Bérar & Baldinozzi function ((1993) J. Appl.
Cryst. 26, 128); anisotropic peak profiling via theAnisotropic Variable method (A. Le Bail & A. Jouanneaux(1997) J. Appl. Cryst. 30, 265) and the StephensPhenomenological method (J. Appl. Cryst. 32, 281(1999)); as well as in-built difference Fourier calculation;and in-built bond length and angle calculation. Anotherfeature (besides standard distance and angle bondrestraints) is the ability to perform “same” bond-length
restraints; which can be very useful for refinement ofmolecular organic structures. Other features include theability to output to a wide variety of third party programs
such as Shelxs/Shelxl, Platon WinOrtep, EXPO, Struvir,
WinStruplo, WinPlotr and GFOUR Fourier software. A
graphical shell for Windows, displaying Rietveld plot files
and calling the various ASCII input files is included withthe distribution.

Fig 11: Example of a Norbornene Rietveld goodness of fit
plot in the WinMprof MS-Windows interface
overlaid with the structure of Norbornene. The
refinement included the use of anisotropic pseudoVoigt PSF (P.W. Stephens (1999) J. Appl. Cryst. 32,281) and Bayesian constraints on distances andangles in the molecules. As cited in M. Brunelli,
A.N. Fitch, A. Jouanneaux and A.J. Mora “Crystal
and molecular structures of norbornene” Zeitschrift
fur Kristallographie vol 216, p 51-55 (2001).

Fig 10: Screen image of Rietica running a multi-dataset
refinement involving 22 powder histograms.

XND
Rietveld structure refinement on normal andincommensurate structures and real-time powder
diffraction refinement
OS:
PC Windows, UNIX, Linux, SunOS SGI IRIX, HP-UX(“c” source code included)
Contact: Jean-Francois Berar
Email: berar@polycnrs-gre.fr
WWW:
http://www-cristallo.polycnrs-gre.fr/xnd/xnd.html
Download: ftp://ftp.polycnrs-gre.fr/pub/xnd/
References: G. Baldinozzi, D. Grebille and J-F. Bérar,Proceedings of Aperiodic' 97, World Scientific (1999)
p297-301.
The major abilities of the XND Rietveld includes therefinement of incommensurate structures; refinement ofmultiple datasets (Bragg-Brentano X-ray, neutron,
synchrotron); and of combined refinement of a range of
powder diffraction patterns changing by a parameter (suchas temperature, pressure, magnetic field, electric field,
time, etc). If the structure is unknown, the lattice can bemodelled by the Le Bail method; and if the lattice isunknown, d-spacings can be modelled. XND can handle
anomalous scattering for the analysis of multi-wavelength
experiments (such as distinguishing the valences of ions incomplex ferrites).
Control of the refinement is performed via the editing ofan ASCII control file. Other features include the ability tohandle variable step scans; modelling of parasitic
wavelengths (Tungsten, K-beta, etc); and setting up
equations linking together various parameters. Besides themain XND documentation, some tips on using XND are
available at http://www.ccp14.ac.uk/tutorial/xnd/.

Fig 12: Example of an XND refined structure; an idealised
view of the incommensurate Sr14Cu24O41 typestructure as cited in : S. Pachot, C. Darie, J.F. Berar,
P. Bordet, C. Bougerol-Chaillout; “Refinement ofincommensurate misfit compounds : Sr14xCaxCu24O41” EPDIC 7, Barcelona; to appear inMaterial Sciences Forum.

XRS-82/DLS
Rietveld structure refinement (with restraints) anddistance least squares refinement
OS: UNIX, Linux, VMS, DOS, OS/2
Contact: Christian Baerlocher
Email: ch.baerlocher@kristall.erdw.ethz.ch
WWW: http://www.kristall.ethz.ch/LFK/software/
Download: http://www.kristall.ethz.ch/LFK/software/xrs/
References: Ch. Baerlocher: The X-ray Rietveld System,
XRS-82, Version of September 1982. Institut fuer
Kristallographie und Petrographie, ETH Zuerich and Ch.
Baerlocher, A. Hepp, W.M. Meier: DLS-76, a program forthe simulation of crystal structures by geometricrefinement.
Institutfuer
Kristallographie
undPetrographie, ETH Zuerich.
XRS-82/DLS is a Rietveld system primarily associatedwith the modelling and refinement of complex zeolitic
structures. The primary interface in controlling the
program is a series of ASCII files. In principle, there is nolimit to the number of atoms that XRD-82/DLS canhandle; as long as there are more restraints (bonds/angles)
than there are variable atom co-ordinates.
For assistance in generating DLS and XRS-82 control
files, Kriber by Roland Bialek can be used(http://www.kristall.ethz.ch/LFK/software/kriber/).

Fig 13: A 117 atom zeolite structure refined with
XRS82/DLS as published in: Wessels, T.,
Baerlocher, Ch., McCusker L.B. and Creyghton,
E.J. "An ordered form of the extra-large-pore
zeolite UTD-1: its synthesis and structure analysis
from powder diffraction data" (1999) J. Am. Chem.
Soc., 121, 6242-6247

Dealing with unknown impurity phases
W I F David,
ISIS Facility, Rutherford Appleton Laboratory,
Chilton, Oxon., OX11 0QX, UK
INTRODUCTION
What do you do when you want to perform a Rietveld
analysis of a particular material but have a substantial
impurity phase and despite all your best attempts you canneither remove it from your sample nor index it from yourdiffraction pattern? Conventional wisdom would state thatyour chances of obtaining unbiased structural parameters
are poor and that the best you can do is to manually
exclude the offending impurity peaks. Standard Rietveld
programs that are based upon a least-squares refinement
algorithm cannot cope in an unbiased manner with anincomplete model description of the data. This is just thesituation where Bayesian probability theory can come to
the rescue. We can ask the question, “How do I perform arefinement on a powder diffraction pattern when I knowthat there is an impurity phase present but have no idea
what that impurity phase may be?” This question isequivalent to stating that my diffraction pattern contains acomponent that I can model (known phases + background)and an additional positive, unknown contribution. It turns
out that enforcing the positivity of the unknown
component as an additive contribution is sufficient toproduce excellent results [1].
The mathematical development of these ideas has
been presented elsewhere [1,2] and results in a modified χ2goodness of fit function that is shown in Fig. 1. For
observed data that are less than the model function, the
new goodness of fit behaves essentially identically to thestandard χ2. This is to be expected since such points areunlikely to be associated with an impurity contribution. On
the other hand, when the observed data value issubstantially greater than the fitted model value, then the
new goodness of fit brings a substantially smaller penalty(the function varies logarithmically) than the quadratic
behaviour of the standard χ2. Again this is just what isrequired to minimise the impact of any impurity phase.
Note also that the curvature of the new goodness of fit isshallower than the standard χ2. This means that quoted
standard deviations will be higher for refinements using
the new goodness of fit. This is to be expected as theallowance for an impurity phase brings a greater
uncertainty into the model parameter values.
EXPERIMENTAL
Diffraction patterns of yttria and rutile were collected on
HRPD at ISIS. Results from the 5% yttria : 95% rutile areshown in Fig 3. (The fitted diffraction pattern of pure yttria
is shown in Fig 2 for comparison.) In order to accentuate
the difference between the new goodness of fit function
and standard least-squares analysis, we have chosen torefine the minority yttria phase treating the majority phaseas the impurity (see Fig 3a). The excellent fit to the data
for the modified χ2 is shown in Fig 3b where we havegraphically downweighted the observed points, which
contribute least to the goodness of fit. This emphasizes

Fig. 1 The modified robust goodness of fit function(solid line) compared with the standard quadratic
least-squares function.

Fig. 2. The observed and calculated diffraction
patterns for pure yttria determined on HRPD at
ISIS.
what the algorithm is effectively doing – large positive(obs-calc)/esd values are essentially ignored. In effect, thealgorithm is optimally excluding those regions that do notcontribute to the model. The relative calculated peakintensities agree very well with the results for pure yttria(Fig 2).
Least squares analysis (Fig 3c) produces a completely
different result – all points are considered with nodownweighting for possible impurities. The first obvious
effect is that the refined background is too high. The
reason for this is obvious since the strong impurity peaks
lift up the model fit. The relative peak intensities are
however also very different from the correct values
suggesting that the refined structural parameters aresubstantially in error. This is indeed the case and is borneout by analysis of the refined zirconium and oxygen
coordinates, which are shown graphically in Fig 4 as afunction of yttia content. We briefly consider the otherrefined parameters (a fuller analysis is given in [1]). The
scale factor is correct within estimated standard deviation(esd’s) for the robust analysis but behaves wildly for the
standard least squares, exceeding 1000% for 25% yttria
content. The least-squares analysis of the lattice constantalso becomes increasingly unreliable as the refinement
locks into peaks associated with rutile as well as yttria. On
the other hand, the lattice constant from the robustrefinement is satisfyingly stable; the esd’s increase as theyttria content decreases (the 5% e.s.d. is some five times
larger than the 100% value) but all results lie within astandard deviation of the correct result.

CONCLUSIONS
Least-squares Rietveld analysis is the best and leastbiased method of structure refinement from a powder
diffraction pattern when the data can be fully modeled.
However, when there is an unmodeled impurity
contribution in the diffraction pattern, least-squares
analysis gives biased results. In the example discussed inthis contribution, significant deviations from the correct
parameter values occur when there is as little as a 10%
impurity contribution. At higher impurity levels, leastsquares analysis is completely unreliable. These problems
may, however, be overcome if the existence of an
unknown impurity contribution is built into the refinement

Fig 4. The refined atomic coordinates of yttria plotted as a functionof yttria composition. Open circles and filled squares
correspond to the least-squares and robust analyses,
respectively. (a) The yttrium x coordinate. (b), (c), (d) The
oxygen x, y and z coordinates. The dotted lines correspond tothe correct values obtained from least-squares refinement ofthepure-yttria

diffraction

algorithm. While it might seem to be a logicalinconsistency to build in information about an unknown
contribution, Bayesian probability theory provides aframework for doing just this. Only two broad assumptions
are necessary to derive an appropriate modified probability
distribution function. These are (i) that the impurity
contribution must be intrinsically positive and (ii) that its
magnitude, A, is unknown and thus best modeled by aJeffreys' prior, given by p(A|I) 1/A for A > 0 and p(A|I) =0 for A 0. This produces a modified ` 2' function (seeFig. 1) that effectively excludes the impact of impurity
peaks.
The results discussed in briefly in this contribution andmore extensively in [1] show that the improvement overconventional least-squares analysis is dramatic. Indeed,even in the presence of very substantial impurity
contributions (see Fig. 4) the refined structural parameters
are within a standard deviation of their correct values.
It must, however, be stated as a final caveat that careshould be taken with this approach and the use of analgorithm that can cope with the presence of impurities
should be seen as a last resort. Indeed, every effort should
be made to determine all the phases in a sample. It is much
more desirable to include the impurity phase in a standard
Rietveld refinement.
REFERENCES[1] David, W. I. F. (2001). J. Appl. Cryst. 34 691-698.
[2] David, W. I. F. & Sivia, D. S. (2001). J. Appl. Cryst.
34, 318-324.

Fig 3. Observed and calculated diffraction patterns for thecomposition 5% yttria : 95% rutile: (a) robust analysis
showing the full observed data range (the grey scale
described in the text not used in this figure); (b)expanded region highlighting the successful robustrefinement (the down-weighting grey scale is used inthis figure); (c) the least-squares analysis showing thepoor agreement between the observed and calculated
patterns.

Rietveld refinements with JANA2000
M. Dusek1, V. Petricek1, M. Wunschel2, R. Dinnebier3 andSander van Smaalen2
1

Institute of Physics, Academy of Sciences of the Czech
Republic, Praha, Czech Republic,
2
Laboratory of Crystallography, University of Bayreuth,
Universitätsstrasse 30, D-95440 Bayreuth, Germany,
3
Max Planck Institute for Solid State Research,
Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
E-mail: smash@uni-bayreuth.de
The system of computer programs JANA2000 is designed
for the refinement and analysis of incommensurately
modulated structures and composite crystals as well as
periodic crystals. It incorporates many different
possibilities to use restrictions on the parameters, like theuse of non-crystallographic site symmetry and the directrefinement of temperature factors in the TLS formalism.
Here we describe the powder module of JANA2000, thatallows Rietveld refinements and the LeBail fits of powder
diffraction data with the full functionality of the JANA2000
system, including Rietveld refinement of incommensurate
structures.
INTRODUCTION
Rietveld refinement of crystal structures against powder
diffraction data has become a standard technique for the
structural analysis of compounds with small unit cells.
Synchrotron radiation is responsible for a very small
instrumental line width. The increased resolution has
pushed the limits of powder diffraction towards theanalysis of more complex compounds. The much better
signal to noise ratio of diffractometers based onsynchrotron radiation has allowed the study of weaksuperlattice effects. Concomitantly, the past decade has
seen the development of profile functions, that accurately
describe the peculiar shapes of these high-resolution
reflections. These developments are available in several
extensive software packages like GSAS [1].
Incommensurately
modulatedstructures
andincommensurate composite crystals have been studied byquantitative single-crystal x-ray diffraction for the past 25
years [2]. The description of their structures andsymmetries requires the superspace theory [3]. Presently,
the system of computer programs JANA2000 provides themost extensive set of tools for the analysis ofincommensurate structures [4]. JANA2000 has several
unique features, including a great flexibility in the choiceof the types of modulation functions. Many options in
JANA2000 are useful for the analysis of periodic crystals
too. Examples are the possibility to refine the temperatureparameters in terms of rigid-body motions (TLS
formalism), anharmonic temperature parameters and theirmodulations [5], and the possibility to apply restrictions
according to non-crystallographic symmetries of molecules[6].
A powder module was introduced into JANA2000, in orderto make all its features available for Rietveld refinement[4]. In this contribution we give a short introduction to
incommensurate structures and we discus the specificproblems that arise for the analysis of powder diffractionof aperiodic crystal structures. In the second part theimportance is shown of the use of restrictions according to
non-crystallographic symmetries.
INCOMMENSURATE CRYSTALS
Incommensurately modulated crystals lack 3-dimensionaltranslation symmetry [2]. Yet their structures have perfectlong-range order, as it is reflected by a diffraction patternconsisting of sharp Bragg reflections. All Bragg reflections
can be indexed with four or more integers according to

H = h a* + k b* + l c* + m1 q1 + L + md q d{a*, b*, c*} form the reciprocal lattice of the basic orjaverage structure. The modulation wave vectors q are
given as a linear combination of the 3 basis vectors ofreciprocal lattice of the average structure:q j = σ j1a* + σ j 2b* + σ j 3c*
d is the dimension of the modulation; usually it is restricted
to 1 or 2.
The main reflections (h, k, l, 0) form a reciprocal lattice. Ifsatellites (h, k, l, m) of all orders |m| would be present, thenthey would lie dense on a line through reciprocal space.
For the powder diffraction this implies, that there would bea dense set of reflections along the 2θ axis. Obviously, afull profile analysis with an infinite number of reflections
is not possible. In real structures non-zero intensities are
only observed up to a maximum order of the satellite
index, usually up to |m| = 2. For applications of the
Rietveld method to modulated structures it is thus required
to restrict the maximum possible m-index to some value|m|max. This option has been included into the Rietveld
module of JANA2000.
Figure 1 shows a screenshot of JANA2000 displaying theresult of a Rietveld refinement of the incommensurately
modulated structure of NbTe4. The graphical user interface
is visible, and the figure shows that JANA2000 offers many
possibilities to vary and analyze the plot. With |m|max = 2
the reflections within this region of 2θ are all isolated. In
Figure 2 the regions around 2θ = 31 deg. and around2θ = 42 deg. are displayed. They show the good fit to themeasured data, including relatively large intensities forsome first-order satellites.

Fig. 1 Screenshot of JANA2000 displaying the Rietveld plot of theincommensurately modulated structure of NbTe4. With the"Plot Powder Profile" module the Rietveld plot or the resultof the LeBail fit can be displayed in a great variety of ways.
Information about the refinements and resulting parameters
is available as a printable file.

Fig. 3 The structure of C60 molecule in COXC60 after refinementwith (left:) rigid bodies in gsas, and (right:) icosahedral site
symmetry in JANA2000. Thermal ellipsoids are shown.

Fig. 2 .Two excerpts of the Rietveld plot of NbTe4. Satellite
reflections up to order |m|max = 2 are shown.

Indeed, the Rietveld refinement resulted in basic structure
parameters and modulation parameters that were equal to
but less accurate than those obtained from the singlecrystal refinement [4,7]. Composite crystals or
incommensurate intergrowth compounds can be consideredas the intergrowth of two incommensurately modulated
structures. In the simplest example the first subsystem has
main reflections (h, k, l, 0) while the second subsystem has
main reflections (h, k, 0, m). The main reflections(h, k, 0, 0) are common to the two subsystems, while theremaining main reflections of one subsystem are satellitesof the other subsystem. Reflections (h, k, l, m) with both land m non zero are satellites of both subsystems. In orderto describe all reflections with non-zero intensities, it is
now necessary to restrict the minimum value of the pair(|l|, |m|) to some maximum value mmax. This option has
been included into the powder module, and it is thus
possible to perform Rietveld refinements of composite
crystals with JANA2000.
NON-CRYSTALLOGRAPHIC SITE SYMMETRY
Because modulated structures are described as the sum of abasic structure with 3D translation symmetry andmodulation functions, any computer program formodulated structures can also handle ordinary 3D periodic
structures. In addition JANA2000 can treat many special
structural features, like anharmonic temperature factors,
the TLS formalism, rigid-bodies, and the noncrystallographic site symmetries. The crystal structure of
COXC60 has been solved by synchrotron radiation x-ray
powder diffraction at T = 25 K [8]. The C60 molecules
form a cubic closed packed crystal with the CO moleculeson the octahedral sites (space group Pa 3 ). Rietveld
refinements using all 10 crystallographically independent
atoms of the C60 molecule are not possible, because of thehigh correlations between these parameters. In the previous
study Rietveld refinements were performed using a rigid
body for the C60 molecule. Although anisotropic
temperature parameters were used for this rigid body, therefinement led to an almost isotropic temperature tensor(Fig. 3a). The reason is, that this tensor can only describe
displacements of the rigid body, and the latter are expected
to be equal in all directions. Alternatively, the C60
molecule can be described as a molecule with icosahedral
symmetry. Then there is only one independent atom.

Refinement of its coordinates allows for the variation of
the size of the molecule and the ratio of the long and shortbonds. This refinement with JANA2000 lead to virtually thesame geometry of the molecule as the rigid body.
However, the temperature parameters were now a single
temperature tensor for the independent atom. The
icosahedral symmetry transplants this tensor towards allother 59 atoms, whereby the directions of the principal
axes are transformed according to the point symmetry. As
it follows from the refinement this description leads to ananisotropic temperature movement, that clearly reflects
librations of the molecules that are larger than theirtranslations, in accordance with the expectations (Fig. 3b).
The consequence of this improved description of theelectron density was a significant change in the position of
the CO molecule, and a significant change in occupancy ofthis site from x = 0.67 to x = 0.85 in the new refinement.
CONCLUSIONSThe system of computer programs JANA2000 can be used
for the LeBail fit of powder diffraction data as well as for
Rietveld refinements. JANA2000 incorporates parameters
for the description of modulated and composite crystals
and for atypical structural features of ordinary crystals, likeanharmonic temperature tensors and non-crystallographic
site symmetries. All these options are available for the
Rietveld refinement.
Financial support was obtained from the German Science
Foundation (DFG), the FCI, and the Grant Agency of the
Czech Republic (grant 202/00/0645).}
REFERENCES[1] Larson, A. C. & Von Dreele, R. B. (1995). GSAS -General Structure Analysis System.} Los Alamos
National Laboratory Report LAUR 86-748.
[2] Van Smaalen, S. (1995). Cryst. Rev. 4, 79-202.
[3] De Wolff, P. M., Janssen, T. & Janner, A. (1981). Acta
Cryst. A37, 625.
[4] Dusek, M., Petricek, V., Wunschel, M., Dinnebier, R.
E. & van Smaalen, S. (2001). J. Appl. Cryst. 34, 398.
[5] Pfitzner, A., Evain, M. & Petricek, V. (1997). Acta
Cryst. B53, 337.
[6] Van Smaalen, S., Petricek, V., De Boer, J. L., Dusek,
M., Verheijen, M. A. & Meijer, G. (1994). Chem. Phys.
Lett. 223, 323.
[7] Van Smaalen, S., Bronsema, K. D. & Mahy, J. (1986).
Acta Cryst. B42, 43.
[8] Van Smaalen, S., Dinnebier, R. E., Holleman, I., Von
Helden, G. \& Meijer, G. (1998). Phys. Rev. B57,
6321.

No Internet acc

No
blem
pro

OCTOBER 2001 EDITIONOUT NOW!

ess?

If you’re working in thedeveloping world andhave limited or no accessto the Internet, then the
Xtal Nexus CD-ROM ishere to help.
Packed with a host of crystallographic
software packages and resources, thesevirtual Internet CD-ROMs have been producedwith the permission of software and website custodians. The organizer of the Nexus project, theIUCr Committee on Electronic Publishing, Dissemination and Storage of Information, invites
academics and students in crystallography working in laboratories in developing countries that are
isolated from the Internet to register their interest. The CD-ROMs are free of charge and available
while stocks last.
The CD-ROM is sponsored by the IUCr and the Collaborative Computational Project No. 14(CCP14) for Single Crystal and Powder Diffraction.

Contents
Multiple software packages and suites relevant to single-crystal, powder diffraction,
crystallographic structure validation and crystallographic teaching, including• single-crystal structure solution and refinement suites for PC• crystallographic structure visualization programs• powder diffraction pattern visualization, peak profiling and indexing software• powder diffraction structure solution• classic and modern crystallographic program source code
• Rietveld refinement packages• structure validation and checking software• powder pattern simulation and journal-quality structure plotting and photorealistic
rendering programs• educational websites dealing with crystallographic teaching• webpage-based tutorials on how to use many of the programs within the CD-ROM• part of the IUCr website including IUCr Commissions.

Send your request for a free
Xtal Nexus CD-ROM (preferably via
e-mail or by conventional mail) to
Lachlan M. D. Cranswick
CCP14 – School of Crystallography,
Birkbeck College, Malet Street,
Bloomsbury, London WC1E 7HX, UK
E-mail: l.m.d.cranswick@dl.ac.uk
Tel:+44 20 7631 6849
Fax:
+44 20 7631 6803
WWW: www.ccp14.ac.uk

The CD-ROMs, and regular updates,
will be sent by airmail.

Computer Corner
Updates on Freely Available Crystallographic and Powder
Diffraction Software(Suggestions,corrections,comments
appreciated;
especially if you know of new program features, program
updates and announcements that should be mentionedhere).

outputs files in a suitable format (the latest WinMprof
Rietveld outputs GFOUR input and reflection files).
GFOUR also includes the ability to define the format of
the reflection file via a Graphical User Interface (GUI)anduses flexible, free format input files which willpleasantly surprise people used to programs such as the
1960’s/1970’s/1980’s/1990’s vintage Fordap input files ofones and zeros.

Lachlan M. D. Cranswick
Collaborative Computational Project No 14 (CCP14) for
Single Crystal and Powder Diffraction
CCP14 - School of Crystallography,
Birkbeck College,
Malet Street, Bloomsbury,
WC1E 7HX, London, UK
Tel: (+44) 020 7631 6849
Fax: (+44) 020 7631 6803
E-mail: l.m.d.cranswick@dl.ac.uk
WWW: http://www.ccp14.ac.uk - http://ccp14.sims.nrc.ca- http://ccp14.semo.edu
CCP14 US and Canadian full Software mirrors
Thanks to Ronald Rogge and Ian Swainson of the NRC,
Chalk River, Ontaria, Canada and Marcus Bond ofSoutheast Missouri State University, USA, the CCP14(Collaborative Computational Project No 14 for Single
Crystal and Powder Diffraction) now has full mirrors ofthe main UK website in Canada and the USA.
UK: http://www.ccp14.ac.uk/
US: http://ccp14.semo.edu/
CA: http://ccp14.sims.nrc.ca/
If you find the links to the following (and other) mentioned
software are slow or unavailable from their original web or
FTP sites, go to the CCP14 mirrors / “download software”
page, do a “text find” on the name of the software you areseeking and go to what looks likes the fastest local mirror
from your region of the world.

Fig 1: a) example of the GFOUR menu system and b)
example of the “File, New” menu option including theability to define the format of the reflection file via the
GFOUR Graphical User Interface (GUI)

CCP14 main “Mirror” / “Download Programs” pages:
UK: http://www.ccp14.ac.uk /mirror/
US: http://ccp14.semo.edu /mirror/
CA: http://ccp14.sims.nrc.ca /mirror/
Another alternative is use the “CCP14 search” page; or a
Google search (http://www.google.com). Though if any
doubt, or if you feel slightly lost or confused about how tostart, feel free to contact the CCP14 via E-mail at
ccp14@dl.ac.uk.
GFOUR for Windows Fourier Map Software by Javier
Gonzalez-Platas and Juan Rodriguez-Carvajal
The latest GFOUR Fourier Map generation, peak find andcontour map display software (updated 25th September2001) is now available at
ftp://charybde.saclay.cea.fr/pub/divers/fullprof.2k/Windows/ and CCP14 mirrors. This includes new additions andfeatures to the Graphical User Interface (GUI) such as theability to animate through the Fourier contour map.
While GFOUR interlinks with the Fullprof Rietveld
software; it can be used by any Rietveld program thatFig 2: GFOUR displaying a Fourier map; including theautomatic labelling of atoms near the plane being
displayed.

Computational Crystallography Toolbox (CCTBX) by
the Computational Crystallography Initiative (CCI)The CCTBX is an Open Source project for those interested
in crystallographic software development. Organized as aset of ANSI C++ classes with Python bindings, it presently
has a unit cell toolbox (uctbx), a space group toolbox(sgtbx) and an element toolbox (eltbx) for the handling of
scattering factors and other element properties. The
CCTBX can be downloaded at its homesite at:
http://cctbx.sourceforge.net/ or CCP14 mirrors.

Fig 3: Example GFOUR input file viewed via the freeware
PFE (Programmer’s File Editor) for Windows(http://www.lancs.ac.uk/people/cpaap/pfe/).

Ross Angel Equation of State software (EOSFIT, P-V
Calculator) software
Software for Equation of State analysis by Ross Angel at
Virginia Tech is now available on the web at
http://vtso.geol.vt.edu/rja/soft/. EosFit5.2 for DOS (it also
runs under a DOS box in MS-Windows) handles PressureVolume-Temperature data; Pressure-Volume data; and fits
Murnaghan, Birch-Murnaghan, natural strain and Vinet
equations of state. The P-V Calculator version 6 forWindows performs Pressure-Volume calculations, andprovides f, F, and K and K' at pressure. This software canbe useful during these types of experiments during
diffraction beamtime at synchrotron facilities.

Fig 5: CCTBX web interface for determining spacegroups
from symmetry operators and visa-versa at:
http://cci.lbl.gov/servers/cctbx/explore_symmetry.html.
It can also handle Shelx style input for discovering thespacegroup from symmetry operators. Refer "Algorithms
for deriving crystallographic space-group information", R.
W. Grosse-Kunstleve Acta Cryst. 1999, A55:383-395
ObjCryst++ “open source” crystallographic sourcecode library and FOX “real space” structure solution
software byVincent Favre-Nicolin
A new resource for crystallography and powder diffraction
software development is Vincent Favre-Nicolin’s
ObjCryst++ crystallographic source code library whose
homesite is at http://objcryst.sourceforge.net/ (with mirrors
at the CCP14). The library presently concentrates onsource code for the global optimisation of crystal structuresfrom diffraction data. This has been released under the“The Artistic License” (described at:
http://www.gnu.org/philosophy/licenselist.html#ArtisticLicense).

Fig 4: Screen images of P-V (Pressure, Volume)
Calculator 6.0 for Windows by Ross AngelA further development from ObjCryst++ is FOX (Free
Objects for Xtallography) for Linux, MS-Windows andsource code. FOX can be used both for educational
purposes as well as to solve crystal structures from powder
diffraction data using global optimisation methods. Objects
or components of a crystal structure can be described as a)atoms, b) organic molecules using a Z-Matrix description,c) or inorganic polyhedra.

Balls and Sticks for Windows by Sung J. Kang &Tadashi C. Ozawa

Of the many notable FOX attributes, one is the ability tooverpopulate your cell with atoms or polyhedral objects
combined with a “Dynamical Occupancy Correction”.
Thus during global optimisation, FOX can merge atoms onshared and special positions using “Dynamical Occupancy
Correction”. These features make FOX attractive forsolving inorganic structures where it is not known (or not
possible to guess) which atoms are on general or special
positions; and/or you are not sure of the connectivity
between different polyhedral objects. A step-by-step
HOWTO web tutorial on using FOX to solve structures isviewable at
http://objcryst.sourceforge.net/Fox/quickstart.html
and CCP14 mirrors.

A newly announced program for the visualisation andanimation of crystal structures including polyhedral
structures and a mixture of polyhedral and ball and stick
structures (with the emphasis on “ease of use”) is the“Balls and Sticks” software by Sung J. Kang and Tadashi
C. Ozawa. Its website is viewable via
http://www.toycrate.org/. “Balls and Sticks” will import
CIF files, then polyhedra and bonds can be defined using
point and click on the mouse. All options are implemented
via the Graphical User Interface (GUI)Because FOX is supplied with source code as part of it
being an “open source” project, it is possible for users tobuild on the existing algorithms in FOX and expand its
functionality and optimisation criteria.

Fig 7: “Balls and Sticks” interface where new polyhedra
are defined by pointing and clicking on the vertices atoms([CONTROL] button is used to select multiple atoms).
Ball atom display can be resized individually or en-masseby right clicking in the Atoms dialog and selecting
properties.

Fig 6: Screen image of FOX solving an inorganic
structure (Lead Sulphate) by simultaneous fitting to
Neutron and X_ray diffraction data. The data andstructure are being simultaneously displayed and updated
in real time during the structure solution process. In the
crystal structure display (top right), you can visually see
the “Dynamical Occupancy Correction” combining atoms
and sulphate groups (defined as tetrahedra) at the special
positions.
Freely available polyhedral structure viewing software
There are many programs are available for generating
ORTEP structure diagrams and ball and stick structuredrawing suitable for chemical crystallography. However,as freely available polyhedral structure drawing software isnot so obvious to find, following is a list of software. It
should be noted that commercial programs exist with thisfunctionality;
includingAtoms
forWindows(http://www.shapesoftware.com), Carine for Mac andWindows(http://www.esm-software.com/carine/)
CrystalMaker for Mac (http://www.crystalmaker.com/) andDiamond for Windows(http://www.crystalimpact.com/diamond/).

Fig 8: Static screen capture of crystal structure GIF
animations generated by Balls and Sticks as viewable on
the Balls and Sticks website via http://www.toycrate.org/.

DrawXTL for Windows, Mac, UNIX and C source codeby Larry Finger and Martin Kroeker
DrawXTL version 3 is downloadable off the web at
http://www.lwfinger.net/drawxtl/ and CCP14 mirrors. It
will render ball and stick structures; ORTEPs, andstructures in polyhedra of any desired shape. Besides its
own native format, DrawXTL can read CIF, CSD, GSAS,SCHAKAL, and SHELX formats. Structures can berendered in VRML1, and structure animations created in
VRML 2 format (requiring a VRML2 viewer to see theanimations)traditional HPGL and Postscript (via the PSPLOT program
included with the distribution). Traditional Struplo91
ASCII files are used for input.

GUI WinStruplo by Louis Farrugia
GUI WinStruplo is a port of Armel Le Bails Struvir code
implemented by Louis Farrugia. Louis has added agraphical user interface with point and click operation, andthe ability to import a large variety of file formats. Fileformats include CIF, Shelx, GSAS, Fullprof and GSAS
and it is available via Louis Farrugia’s site at Glasgow
University, http://www.chem.gla.ac.uk/~louis/software/.

Fig 9: Drawxtl Shell for Windows on the left overlaid with
VRML structure displayed in the interactive COSMO
VRML viewer (installed as a “plugin” within Netscape).
Struvir by Armel Le Bail
Struvir is an Armel Le Bail port of the original Reinhard
Fischer’s Struplo code (R.X. Fischer, J. Appl. Cryst. 18(1985) 258-262). The software modification history issomewhat more complicated, involving modifications or
documentation by: A. Le Lirzin, D. Kassner, Tim
McCarthy, Donald L. Ward, Donald L. Ward, W. H. Baurand Mark Koennecke. Structures can be outputted in
VRML format (Virtual Reality Modelling Language),
Povray files (http://www.povray.org), as well as theFig 11: a) GUI WinSTRUPLO importing a structure readyfor output to supported formats such as HPGL, Postscript,
VRML or Povray (freeware photorealistical rendering
software – http://www.povray.org). b) Structure rendered
by Porvay.

Glassvir by Armel Le Bail for polyhedral viewing of glassmodels generated by RMC (Reverse Monte Carlo)
Glassvir by Armel Le Bail is available at http://sdpd.univlemans.fr/glasses/glassvir.html and is designed for thegeneration of interactive wire-frame and polyhedral
VRML views of glasses modelled by RMC; with the input
being that of the RMC config file (.cfg). Some available
RMC (Reverse Monte Carlo) modelling software includes
that of Robert McGreevy’s; described at
http://www.studsvik.uu.se/software/rmc/rmc.htm
and downloadable via
ftp://www.studsvik.uu.se/pub/rmc_mcgr/.
Fig 10: VRML Structure generated by Struvir anddisplayed in the interactive COSMO VRML viewer(installed as a “plugin” within Netscape).

Xtal-3d by Marcus Hewat (also part of Alan Hewat’s
ICSD for WWW)
Xtal3Dby
MarcusHewat
isavailableat
http://barns.ill.fr/dif/icsd/xtal-3d.html and will render the
structure into the interactive VRML (Virtual Reality
Modelling Language). It can be used as a standalone
command line or GUI based program; as well as via a web
interface. Xtal3D is also included with Alan Hewat’s“ICSD for Web” which has its master website at
http://barns.ill.fr/dif/icsd/.

Fig 12: a) Glassvir generated “wireframe” structure of a
RMC modelled glass in VRML format as viewed
interactively in the COSMO VRML viewer (in this caseinstalled as a Netscape plugin) and b) polyhedral view of
an RMC modelled glass in VRML format.

Xtaldraw (Shareware) by Kurt L. Bartelmehs and Bob
Downs
The Xtaldraw shareware software has its webpage at
http://www.infotech.ns.utexas.edu/crystal/ and CCP14
mirrors. Crystal structure information is entered into a freeformat ASCII control file followed by running Xtaldraw.
Keyboard and mouse control can then be used to generate
the required view for rendering as a GIF file. Spheres,
ellipsoids, bonds and polyhedra can be rendered by
Xtaldraw.

Fig 14: A polyhedral view of rutile as rendered into VRML
by Xtal3D within the ICSD for WWW database.
Updated Gretep (Grenoble Thermal Ellipsoids Plot
Program) by Jean Laugier and Bernard Bochu
The latest version of Gretep for ball and stick structure
plotting allows for i) creating Metal-Ring bonds ii) bondlabels horizontal or oblique to the bond and iii) custom
bond colours. While using these features are quite
elementary via the Gretep Graphical User Interface (GUI),
there are also web tutorials via the Gretep website at
http://www.ccp14.ac.uk/tutorial/lmgp/#gretep and can be
downloaded at:
http://www.ccp14.ac.uk/ccp/web-mirrors/lmgp-laugierbochu/.

Fig 13: Silicate as rendered by XtalDraw.

Fig 15: Gretep screen image showing Metal-atom bonds;
bond labels and custom bond colours (not evident in a
black and white newsletter).

Crysfire by Robin Shirley and Chekcell by Jean
Laugier and Bernard Bochu powder indexing software
updates
It can be useful to regularly check for software updates,
bug fixes and new features; Crysfire and Chekcell being no
exceptions. Both the Crysfire powder indexing suite and
Chekcell have had miscellaneous bug fix updates since thetime of the last CPD newsletter. The Crysfire webpage is
at http://www.ccp14.ac.uk/tutorial/crys/ and with the
Chekcell homepage at
http://www.ccp14.ac.uk/tutorial/lmgp/#chekcell.
Updates in the “EFLECH” automatic fundamental
parameters peak hunting and profile fitting programand “Index” powder indexing software by Jörg
Bergmann
Eflech and Index have undergone miscellaneous
improvements and are available at
http://www.bgmn.de/related.html and CCP14 mirrors.
Traditionally, Eflech will automatically hunt for peaks in a
powder diffraction pattern using the fundamental
parameters peak profiling model to generate a peak listingwith a covariance matrix.
As using “fundamental
parameters” fitting is almost akin to running the sample onan “ideal” diffractometer, properly modelled peak
positions can be of very high accuracy. The “Index”
program will then attempt to index the Eflech determined
powder peaks while making use of the covariance matrix
also generated by Eflech. Recent improvements include
fixing a bug for the triclinic search algorithm; changing
some internal searching algorithm constants; and a newfeature which will output a variety of trial cells (in cases
where the information is not sufficient for a loneunambiguous solution).
The latest EFLECH/Index
combination is also distributed for Linux (compiled on
SuSE Linux 7.2), as well as the traditional DOS, Windows
and OS/2 binaries.
Rietveld Software Updates (as of late October 2001):
Hugo Rietveld website:
http://home.wxs.nl/~rietv025/
BGMN (15th September 2001)
http://www.bgmn.de/
DBWS (22nd February 2000)
http://www.physics.gatech.edu/downloads/young/download_dbws.html
Debvin (25th May 2001)
ftp://ftp.cc.uniud.it/DEBVIN/
GSAS (25th October 2001)
ftp://ftp.lanl.gov/public/gsas/
Jana (31st May 2001) (Email authors for latest Beta test
versions)
http://www-xray.fzu.cz/jana/jana.html
LHPM-Rietica (7th December 2000)
ftp://ftp.ansto.gov.au/pub/physics/neutron/rietveld/Rietica_LHPM95/
MAUD for Java (GPL’d) (2nd August 2001)
http://www.ing.unitn.it/~luttero/maud/
Prodd (3rd April 2001)
http://www.ccp14.ac.uk/ccp/webmirrors/prodd/~jpw22/
Profil (24th May 2001)

ftp://img.cryst.bbk.ac.uk/pdpl/
Rietan 2000 (GPL’d) (6th September 2001)
http://www.ccp14.ac.uk/ccp/webmirrors/prodd/~jpw22/
Winplotr/Fullprof (27th August 2001)
http://www-llb.cea.fr/winplotr/winplotr.htm
ftp://bali.saclay.cea.fr/pub/divers/fullprof.2k/
Winmprof (21st June 2001)
http://lpec.univ-lemans.fr/WinMProf/XND (6th July 2001)
http://www-cristallo.polycnrs-gre.fr/xnd/xnd.html
ftp://old-labs.polycnrs-gre.fr/pub/xnd/
All the above Rietveld programs are also available via the
CCP14 based mirrors in UK, USA and Canada(http://www.ccp14.ac.uk/mirror/).
Summary lists of some software available via the
EPSRC funded CCP14 website:
Anharmonic Thermal Refinement Software
http://www.ccp14.ac.uk/solution/anharmonic/
Data Conversion for Powder Diffraction
http://www.ccp14.ac.uk/solution/powderdataconv/
Image Plate Software
http://www.ccp14.ac.uk/solution/image-plate/
Incommensurate Structure Software
http://www.ccp14.ac.uk/solution/incomm.htm
Indexing Software for Powders
http://www.ccp14.ac.uk/solution/indexing/
LeBail Method for Intensity Extraction
http://www.ccp14.ac.uk/solution/lebail/
Pawley Method for Intensity Extraction
http://www.ccp14.ac.uk/solution/pawley/
PDF, High Q Powder diffraction Analysis Software
http://www.ccp14.ac.uk/solution/high_q_pdf/
Peak Find/Profiling Software for Powder Diffraction
http://www.ccp14.ac.uk/solution/peakprofiling/
Pole Figure and Texture Analysis Software
http://www.ccp14.ac.uk/solution/pole_figure/Powder Diffraction Data Visualisation
http://www.ccp14.ac.uk/solution/powder_data_visual/
Search-Match Phase Identification Software
http://www.ccp14.ac.uk/solution/search-match.htm
Single Crystal Structure Solution Software relevant to Chemical
Crystallography
http://www.ccp14.ac.uk/solution/xtalsolution/
Single Crystal Structure Refinement Software relevant to
Chemical Crystallography
http://www.ccp14.ac.uk/solution/xtalrefine/Single Crystal Suites linking to multiple programs relevant to
Chemical Crystallography
http://www.ccp14.ac.uk/solution/xtalsuites/
Spacegroup and Symmetry operator determination software andsource code
http://www.ccp14.ac.uk/recomm/sym_operators_to_spa
cegroups.html
http://www.ccp14.ac.uk/recomm/spacegroups_to_sym_
operators.html
Spacegroup and Structure Transformation Software
http://www.ccp14.ac.uk/solution/transform/
Structure Conversion and Transformation
http://www.ccp14.ac.uk/solution/structconv/
Structure Drawing and Visualisation
http://www.ccp14.ac.uk/solution/structuredrawing/
Unit Cell Refinement of Powder Diffraction Data
http://www.ccp14.ac.uk/solution/unitcellrefine/MEETING AND SCHOOL REPORTS
3rd Size-Strain Conference,
Trento (Italy), 2-5.12.2001
Paolo Scardi
Dipartimento di Ingegneria dei Materiali
Università di Trento
via Mesiano 77, Trento, ITALY
Tel: +39 0461 882417/67
Fax: +39 0461 881977
e-mail: Paolo.Scardi@ing.unitn.it
Web-site: http://www.ing.unitn.it/~scardi/

The third Size-Strain conference (SS-III) “Analysis of
microstructure and residual stress by diffraction methods”
was is intended as a continuation of the successful series ofSize-Strain conferences initiated in 1995 (Liptovsky
Mikulas, Slovakia) and continued in 1998 (Freiberg,
Germany). The conference was organised under thesupervision of a Technical Programme Committee (R.
Cheary, J. Cline, R. Delhez, P. Klimanek, D. Louer, E.
Mittemeijer, P. Scardi, B. Scholtes, V. Valvoda) and an
International Advisory Board (C. Hubbard, A. Kern, E.
Mittemeijer, P: Munk, P. Scardi, R. Snyder). The Local
Committee (chaired by M. Leoni) provided an
indispensable support to the many practical and logistic
issues.
This event was made possible by the generous financial
support of the European Commission (the conference wasalso included in the list of High-level Scientific
Conferences) and the Regione Autonoma Trentino Alto
Adige-Südtirol. Further important sponsorships by theInternational Union of Crystallography, Philips Analytical,
Bruker, ICDD, Osmic, XOS, Bede and Rich-Seifert were
essential for the organisation and to support theparticipation of young scientists and colleagues from lessfavoured countries.
The general conference topics concerned materials
microstructure and properties, as they can be studied bydiffraction methods. In addition, applications of diffraction
techniques to polycrystalline and amorphous materials werealso discussed. Following the tradition of the previous SizeStrain conferences main themes were methodologies for the
study of lattice defects, residual stress and texture in thinfilms and surfaces, line profile fitting/modeling based on
fundamental parameters, simulation of materials
microstructure and defects related to diffraction profiles.
Particular emphasis was given to materials science
applications, including e.g., phase analysis with amorphous
fraction, highly defective and nanocrystalline materials,
residual stress gradients and stress mapping in thin layers
and coating systems.
The conference was organized around the topics of 13
invited talks (A. Kern, I. Groma, J.-D. Kamminga, N.
Armstrong, A. Ustinov, P. Scardi, J. Cline, R. Birringer, M.
Leoni, C. Genzel, U. Welzel, P: Riello), including the honor
lecture by Ian Langford who presented an overview on thehistory of powder diffraction and line profile analysis
methods in the past century. 15 contributed talks and two
sessions dedicated to posters completed an intensive andinteresting program.

2001

III
TRENTOOne of the targets of the conference was to get
together most of the experts in the main areas of interestand to encourage a free exchange of information anddiscussion among attendees. From this point of view theconference was a real success: long and animateddiscussions followed most of the presentations, thus
providing a real insight into the current research activity.
Front cover of theconference proceeding
bookletParticipants enjoyed the local hospitality, as also
demonstrated by the high popularity of the archeologicaltour (visit to the underground Roman site) and especially of
the social dinner and ‘wine’ tour.
Conference proceedings are collected in a booklet ofextended abstract of all the presented contributions (orals
and posters) which is available on request. Abstract are also
displayed in electronic format on the IXAS web site(http://www.ixas.org). A book, containing full chapters
dedicated to the most significant and pertinent contributions
is currently being edited by the conference Chairs (P.
Scardi and E. Mittemeijer) and should be published within
one year from the conference.
Beyond the scientific program, the conference was also
a nice opportunity to celebrate the long and fruitful carrierof Ian Langford. Even if he formally retired less than two
years ago, he is very active and we all hope Ian willcontinue to significantly contribute to the progress in
Powder Diffraction in future.
As a final remark, it is not to early to think ofcandidates to the organization of a 4th Size-Strain
conference. Proposal and suggestions will be very
welcome.

41

News f ro m t h e
I n t e r n a t i o n a l Ce n t r e f o r D i f f ra c t i o n D a t a(ICDD)

12 Campus Boulevard
Newtown Square, PA 19073-3273
U.S.A.

Phone: +610.325.9814
Fax: +610.325.9823
E-mail: INFO@ICDD.COM
http://www.icdd.com

IXAS Web Site Launched
In the last CPD newsletter, it was announced that an agreement was reached to have the ICDD provide web services
for the International X-ray Analysis
Society (IXAS). The IXAS web site is
now on-line at www.ixas.org. Membership is free and open to the global scientific community—to join, register at the web site. The website provides on-line access to Advances in X-ray Analysis,
Volumes 42 and 43 (proceedings of the 1998 and 1999
Denver X-ray Conferences), as well as recent abstracts
from the Size Strain III—Analysis of Microstructure andResidual Stress by Diffraction Methods Conference, heldin Trento, Italy, 2–5 December 2001.
The IXAS is a not-for-profit, scientific association that
focuses on the use of X-rays, neutrons, and electrons inmaterials characterization. The purpose of the Society is toserve professionals working in the field of materials analysis by: (a) fostering interaction among materials scientists,chemists, physicists, geologists, and others engaged in theuse of X-rays and other radiations, including neutrons andelectrons, for materials analysis; (b) sponsoring meetingsof interest to those in the field of materials analysis; and(c) disseminating information of interest to the materials
analysis community.

The 50th Annual Denver X-ray Conference
The Denver X-ray Conference (DXC) celebrated its 50th
anniversary in the majestic mountains of Steamboat
Springs, Colorado. The conference
was held 30 July–3 August 2001 andattracted approximately 350 attendees and over 200 exhibit personnel.
Conference week began with 15 tutorial workshops, followed by 16 special sessions.
The Plenary session, “Fifty Years of the Denver X-ray
Conference”, gave attendees the opportunity to learn thehistory of what has grown to become the single mostimportant U.S. meeting in the X-ray analysis community.
The session included presentations from the pioneers of
the DXC—William Mueller, Colorado School of Mines;
John B. Newkirk, Colorado Sports Equipment, Inc.; ClayRuud, The Pennsylvania State University; Paul Predecki,
The University of Denver; and Ron Jenkins, (Emeritus)
ICDD. Each speaker highlighted a particular era of theconference, describing the significant endeavors of thetime and how those events influenced the DXC. The lectures and lecturers were immensely entertaining and often
humorous. The experience was nostalgic for some,enlightening for others, and impressive to all.
Several awards were presented at the conference:
The 2001 Barrett Award, established for excellence in the
powder diffraction field,
was presented to David E.
Cox, (Emeritus) Brookhaven
National Laboratory. P.K.
Predecki, The University ofDenver, presented the award.
Newly established in 2001 to recognize scientists for their
lifetime achievement in the advancement of X-rays formaterials analysis, the Jenkins Award was presented to
Ron Jenkins, (Emeritus) ICDD by R.L. Snyder, The Ohio
State University.
C.R. Hubbard, Oak Ridge National Laboratories, presented
the 2001 Hanawalt Award to Raymond P. Goehnerand Joseph R. Michael,
Sandia National Laboratories. This award is given
in recognition of an important, recent contribution
to the field of powder
diffraction. The Hanawalt Award Lecture, “Phase
Identification Using Electron Backscatter Diffraction in
the SEM: A Powerful Tool for Materials Science” waspresented at the plenary session.

Ron Jenkins, (Emeritus)
ICDD, received the Distinguished Fellows Award for
his long and meritorious
service to the ICDD. Julian
Messick, ICDD, presented
the award.

New Products
The ICDD introduces a new product line! The new
database products, PDF-4s, are organized in a relational
database format, which provides extensive data mining inquick time. The PDF-4 products feature a powerful userinterface, PCPDFWIN™, with query sorting capabilities
and integrated viewing software. PDF-4/Minerals 2001 andPDF-4 Metals and Alloys 2001 are now available with
PDF-4/Full File scheduled to be released in the Spring 2002.

Annual Spring Meeting Dates
The ICDD Annual Spring Meetings will be held at ICDD
Headquarters, 18–22 March 2002.

ICDD Welcomes its New Executive Director,
Dr. Tim Fawcett
The ICDD is pleased to announce that Dr. Tim Fawcett
has joined the ICDD as its new Executive Director. Dr.
Fawcett is a longtime ICDD member, ICDD Fellow,
and served on the
Board of Directors
from 1986–1988.
He brings to the
ICDD outstanding
experience in management and R&D
for product development, as well as an exceptional background in X-ray diffraction.
Dr. Fawcett received his B.S. degree with honors from the
University of Massachusetts, and his Ph.D. in Inorganic
Chemistry from Rutgers University in 1979. After graduation, Dr. Fawcett joined Dow Chemical Co., worked in
the X-ray diffraction facility, and then managed the inorganic analysis laboratories of Dow’s Analytical Sciences
Department. From 1989 to 1996, he managed several
groups in Dow's Ceramics and Advanced Materials
Laboratories. Dr. Fawcett was promoted to Sr. Research
Manager and managed Dow's Advanced Technologies
and Inorganic Coatings Group, the Interfacial Sciences
Discipline, and most recently, two of Dow's new productdevelopment areas which involved a portfolio of projects
leading to advanced materials products.

Our new products include the updated Mineral Powder
Diffraction File™ Data Book and Search Manual, a hardcover edition featuring Sets 1–50 of the PDF®. A special
combination price is available on the purchase of thisedition along with our new PDF-4/Minerals 2001.
Additional pricing incentives include a Multiyear License
Renewal Program as well as an expanded Site License
Program. The Multiyear License Renewal Program provides savings on the purchase of multiyear license
renewals for the PDF-2 and PDF-4/Full-File.
In celebration of our “Sixtieth Anniversary”, the ICDD is
introducing special “Anniversary” pricing that offers
savings up to 45% off the list prices for a PDF-2 license
renewal. Now containing over 136,000 patterns, the
PDF® has more than doubled in size in the past five years
with the addition of calculated patterns from the Inorganic
Crystal Structure Database, maintained by Fachsinformationzentrum in Karlsruhe, the continuous additionof patterns of important new materials from the ICDD’s
Grant-in-Aid program, as well as patterns located by the
ICDD’s bibliographic staff. Anniversary pricing provides
a valuable opportunity for noncurrent users to update their
PDF® and significantly improve the quality, accuracy, andcoverage of their work.
The ICDD’s quarterly journal,
Powder Diffraction, has a new
up-to-date look, featuring the leadarticle on the cover. Along with thisnew look, the journal has been
updated to include on-line subscriptions. Subscribers may obtainthe journal in print, on-line, or inprint and on-line together

Further Information
To learn more about the ICDD, its products and services, please visit our web sites: www.icdd.com and www.dxcicdd.com.

IXAS NEWSA few years ago the Denver X-ray Conference organizing
committee established an international committee that met
in Barcelona in May 2000 and founded the International Xray Analysis Society. The By-Laws for this fully electronic
and completely dues-free organization provided for thephasing in of an Executive Council and the establishmentof a web site and focus groups. The last of the elections
establishing the Executive council has just been held andthe first complete council is now in place. The officers are:

They join the previously elected Council members:

Bob Snyder (President)George Havrilla (Vice-President, President-Elect)
Greg McCarthy (Secretary-Treasurer)

IXAS will conduct the first full membership election thisspring for the President-Elect at which time Snyder will
become Past-President and Havrilla will become President.
Our new web page is now in place with the full proceedingsof the last two editions of Advances in X-ray Analysis andall of the latest information on the world’s X-ray
conferences. Software is now in place implementing
discussion groups among all of the Analysis area interest
groups. Visit www.ixas.org to see the developments.

The latest members of the Council are:Jimpei Harada (Japan)
Scott Misture (USA)Silvana Simabuco(Brazil)
Szabina Torok (Hungary)

E. Antipov (Russia)
R. vanGrieken (Belgium)
B. Holynska (Poland)
B O’Connor (Australia)
P. Scardi (Italy)
H. Toraya (Japan)
P. Wobrauscek (Austria)

WHAT’S ON
The following web-site contains an up-to-date andsemi-exhaustive list of conferences and workshops in
crystallography and related areas
http://www.iucr.org/cww-top/mtg.date.html

20 – 23 January 2002 (! new date !)SECOND ISPD--2001
Calcutta and Bangalore, India
Second International School on Powder Diffraction(ISPD--2001)will be held in Jadavpur, Calcutta, India from2ß –23 January, 2002. Lecture sessions include
contemporary topics in powder diffraction by X-ray,electron, neutron and synchrotron radiation, given byexperts with hands-on computer sessions for young andactive researchers in institutes, universities, and companies.
The meeting is sponsored by IUCr, ICDD and otherorganizations.
For further information contact:
For ISPD 2001: Prof S P Sen Gupta,
E-mail:msspsg@mahendra.iacs.res.in,
Fax: 91-33-473 2805
Web-site: www.iacs.res.in/ispd.html
11 – 15 February 2002
AXAA 2002
Newcastle, NSW, Australia
The schools program aims to provide training for early
career professionals. The conference provides anopportunity for professionals with an interest in x-ray andsurface analysis to come together over five days. The
conference aims to: Recognise progress and highlight
future directions for X-ray and surface analysis; develop

44knowledge and expertise in X-ray analysis practice andmanagement; motivate participants to contribute toeffective x-ray fluorescence, diffraction and surface
analysis programs.
For further information contact:
Jane Yeaman
AXAA 2002 Conference
Tulips Meetings Management
PO Box 116, Salamander Bay, NSW, 2317 Australia
Tel 02 4984 2554
Fax 02 4984 2755
Email: axaa@pco.com.au
Web-site: www.pco.com.au/axaa2002/
8-12 April 2002
ADVANCED X-RAY DIFFRACTION FOR PHARMACEUTICALAPPLICATIONS TRAINING SEMINARSThe Eden Resort Inn & Conference Center, Lancaster PA,
USA.
Application of X-ray powder diffraction, in particular its
capability of solving structures from powder data in thepharmaceutical area.
For further information contact:assainternational Inc.
3B East Lake Road
Danbury, CT 06811, USA
Tel: (203).312.0682
Fax: (203).312.0722
E-Mail: info@assainternational.com
Web-site: www.assainternational.com/home.htm

International Centre for Diffraction Data
1941—Sixty Years—2001
Serving the Scientific Community

Release 2001of thePowder Diffraction File™
Featuring❖ Release 2001 totals more than 136,500 patterns❖ Over 87,500 experimental patterns❖ 2,500 new experimental patterns added for Release 2001
❖ Over 49,000 patterns calculated from the ICSD database❖ 2,821 new calculated patterns added for Release 2001
❖ Interplanar (d) spacings, relative intensities (Int), and Miller indices❖ Chemical formula, compound name, mineral
name, structural formula, crystal system,
physical data, experimental parameters,
and references when available❖ Quality mark for each experimental
pattern for estimate of reliability❖ Entries indexed for subfile searches❖ Dedication to detail and scientific purpose❖ Four-tiered editorial process❖ Highest standards for accuracy and quality

Ask about our special Anniversary pricing

Visit us at www.icdd.com
Phone: 610.325.9814 ❖ Sales: 610.325.9810 ❖ Fax: 610.325.9823 ❖ info@icdd.com

ICDD, the ICDD logo, and PDF are registered trademarks of the JCPDS—International Centre for Diffraction Data.
Powder Diffraction File is a trademark of the JCPDS—International Centre for Diffraction Data.

29 April - 3 May 2002
PRACTICAL X-RAY FLUORESCENCE SPECTROMETRY
ICDD, Newtown Square, Pennsylvania, U.S.A.
Covering basics of X-ray spectra, instrumentation design,
methods of qualitative and quantitative analysis, specimen
preparation, review of mathematical matrix correction
procedures, applications for both wavelength and energy
dispersive spectrometry and new developments in XRF.
23 – 26 May 2002
EPDIC 8
Uppsala, Sweden
The scientific programme for the three-day conference
will include invited plenary lectures, contributed talks andposter sessions. A commercial exhibition will also beorganised.
The Programme will cover the topics:
1. Methods and techniques
2. Instrumental development
3. New or improved software
4. Databases
5. Materials Sciences
6. Dynamic studies
7. Studies under non-ambient conditions
8. Industrial processes and applications
9. New research fields
Other contributions relevant or complementary to powder
diffraction are welcome.
Internet: http://www.mkem.uu.se/epdic8
e-mail: epdic8@mkem.uu.se
Tel/Fax: 46-18-471 3733 / 46-18-513548
Surface mail: Attn. Gunilla Lindh
EPDIC-8, Dept. of Materials Chemistry,The Ångström Laboratory
Box 538, SE-751 21 Uppsala, Sweden
3-7 June 2002
FUNDAMENTALS OF X-RAY POWDER DIFFRACTION
ICDD, Newtown Square, Pennsylvania, U.S.A.
Covering instrumentation, specimen preparation, dataacquisition, and qualitative phase analysis.
10 – 14 June 2002
ADVANCED METHODS IN X-RAY POWDER DIFFRACTION
ICDD, Newtown Square, Pennsylvania, U.S.A.
Emphasizing computer-based methods of data collection
and interpretation, both for qualitative and quantitative
phase analysis.
For further information on all ICDD meetings contact:
Education CoordinatorInternational Centre for Diffraction Data
12 Campus Boulevard
Newtown Square, PA 19073-3273
Tel: +(610) 325-9814
Fax: +(610) 325-9823
E-mail: clinics@icdd.com
Web-site: www.icdd.com/education/clinics/

46

29 July to 2 August 2002
THE 51ST ANNUAL DENVER X-RAY CONFERENCE
Colorado Springs, Colorado, U.S.A.
The 51st Denver X-ray Conference will be held at theAdams Mark Hotel (formerly Antlers Doubletree Hotel) in
Colorado Springs, Colorado. The Call for Papers is now
available in hardcopy form and on the website.
For further information contact:
Conference CoordinatorInternational Centre for Diffraction Data
12 Campus Boulevard
Newtown Square, PA 19073-3273
Tel: +(610) 325-9814
Fax: +(610) 325-9823
E-mail: dxc@icdd.com
Web-site: www.dxcicdd.com

6 – 14 August 2002
XIX CONGRESS AND GENERAL ASSEMBLY OF
THE INTERNATIONAL UNION OF
CRYSTALLOGRAPHY
Geneva, Switzerland
A large-scale conference that will address all the main
issues in crystallography during a long and interesting
programme. Even if Powder Diffraction sessions are notspecifically included, a number of microsymposia will be
devoted to several aspects of powder diffraction andmaterials science. The second circular with the preliminary
programme is now available and can be downloaded fromthe web.
For further information contact:
Joel Bernstein Chairperson, Organizing Committee
Menahem Kaftory Chairperson, International Program
Committee
e-mail: Kaftory@techunix.technion.ac.il
Secretariat:
XIIX IUCr,
P.O. Box 50006,
Tel Aviv 61500, Israel
Tel: +(972) 3 5140000
Fax: +(972) 3 5175674
E-mail: iucr@kenes.com
Web-site: http://www.kenes.com/iucr/

How to receive the IUCr CPD Newsletter
If you wish to be added to the mailing list for the Newsletter of the IUCr Commission on Powder Diffraction or havechanged address, please contact the Chairman or simply send an e-mail to CPD@ing.unitn.it

Companies
If you would like to advertise in this twice-yearly newsletter, please contact
Paolo Scardi on e-mail: Paolo.Scardi@ing.unitn.it
Tel: +39 0461 882417/67
Fax: +39 0461 881977

Call for contributions to the next CPD Newsletter (No 27)
The next issue of the CPD Newsletter will be edited by Gert Kruger, to appear in summer of 2002. Gert will greatly
appreciate contributions from readers on matters of interest to the powder diffraction community, e.g. meeting reports,
future meetings, developments in instruments, techniques, and news of general interest. Please contact him for sending
articles and suggestions. Software developments can be directly addressed to Lachlan Cranswick or to the Editor ofNewsletter No 27 (addresses are given below)
Prof. G. J. Kruger (Gert)
Department of Chemistry & Biochemistry, Rand Afrikaans University, P O Box 524, Aucklandpark, South Africa
Tel: +27 11 489 2368 | Fax: +27 11 489 2360
e-mail: gjk@na.rau.ac.za
Dr Lachlan M. D. Cranswick
CCP14, Department of Crystallography, Birkbeck College University of London,
Malet Street, Bloomsbury, WC1E 7HX, London, UK
e-mail: l.m.d.cranswick@dl.ac.uk
WWW: http://www.ccp14.ac.uk

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