bluuebunny/crossref_metadata_2025 huggingface dataset:
Conversion of gamma lithium aluminate to lithium aluminum carbonate hydroxide hydrate
Authors: Beckerman Susan Jacob , Ford Robert B. , Nemeth Mark T.
Published: January 2013

Gamma-phase lithium aluminate (LiAlO2) is a ceramic powder used in molten carbonate fuel cells (MCFCs) and in other nuclear and ceramic applications. Upon exposure to water vapor and carbon dioxide at 25 °C, we have observed that gamma-LiAlO2 converts to lithium aluminum carbonate hydroxide hydrate, Li2Al4(CO3)(OH)12·3H2O(LACHH) and Li2CO3. The conversion was observed by X-ray diffraction (XRD) and carbonate analysis. An equation for the conversion is given, and the morphology is determined by scanning electron microscopy. A high-temperature XRD study and thermogravimetric/differential thermal analysis (TGA/DTA) showed that LACHH decomposes at 250 °C. The decomposition products of LACHH and Li2CO3 react to form first alpha-LiAlO2 and then gamma-LiAlO2 at temperatures of 650 and 1000 °C, respectively.
Chemical accuracy and precision in Rietveld analysis: The crystal structure of cobalt(II) acetate tetrahydrate
Authors: Kaduk James A. , Partenheimer Walt
Published: January 2013

The crystal structure of cobalt(II) acetate tetrahydrate, Co(C2H3O2)·4H2O, has been refined using single-crystal, laboratory powder, and synchrotron powder diffraction data, both individually and in various combinations. The compound crystallizes in the monoclinic space group P21/c, with a=4.80688(3), b=11.92012(7), c=8.45992(5) Å, β=94.3416(4)° at 27 °C, and Z=2. The crystal structure consists of discrete centrosymmetric trans-Co(C2H3O2)(H2O)4 complexes, linked by a three-dimensional network of hydrogen bonds. Each complex participates in 14 hydrogen bonds, 12 intermolecular, and 2 intramolecular. Compared to the single-crystal refinement, refinement of laboratory powder data yielded an average difference in bond distances of 0.02 Å, in bond angles of 3°, and in root mean square atomic displacements of 0.07 Å. The standard uncertainties of the bond distances were 0.01 Å, compared to the 0.001–0.002 Å in the single-crystal refinement. Refinement of the synchrotron powder data yielded improved accuracy and precision. It proved impossible to locate or refine hydrogen positions using a single-powder dataset, but the hydrogens could be refined using rigid groups in a joint refinement of the two powder datasets. Even from powder refinements, it is possible to obtain suitable accuracy and precision to distinguish C–O and C=O bonds, and to examine details of chemical bonding.
X-ray powder diffraction analysis of a nonlinear optical material o–chlorobenzol–benzoyl thiourea
Authors: Jin Zong-ming , Zhao Bo , Zhou Weiqun , Jin Zheng
Published: January 2013

A nonlinear optical material, o–chlorobenzol–benzoyl thiourea (C14H11ClN2OS), has been characterized by X-ray powder diffraction. Experimental values of 2θ corrected for systematic errors, relative peak intensities, values of d, and the Miller indices of 78 observed reflection with 2θ up to 72° are reported. The powder diffraction data have been evaluated, and the figures-of-merit are reported. The unit cell parameters least-squares refined from 28 nonoverlapping peaks of the monoclinic compound with a P2 space group are a=13.2797(4) Å, b=12.4058(8) Å, c=8.1561(2) Å, β=95.398(1)°, V=1337.7(4) Å3, Z=4, Dx=1.444 g/cm3. © 1997 International Centre for Diffraction Data.
Temperature dependence of the structures of solution-grown and melt-grown samples of n-hexatetracontane
Authors: Fenrych J. , Reynhardt E. C. , Basson I.
Published: January 2013

The crystal structures of solution-grown and melt-grown polycrystalline samples of n-hexatetracontane (n-C46H94) in the temperature range 293–359 K have been investigated by X-ray powder diffraction. The solution-grown sample has an orthorhombic structure, with space group Pbc21 and cell dimensions a=4.952 Å, b=7.424 Å, and c=120.95 Å. While heating this sample a gradual transition to a monoclinic phase takes place, with onset temperature 335 K. At temperatures close to the melting point two configurations of the ab plane have been observed. Cooling a sample from the melt results in a mixture of a monoclinic and an orthorhombic structure. Rietveld refinements of the structures of solution-grown and melt-grown samples at 293 K have been performed.
Synthesis and structural study from X-ray powder diffraction of Pb0.5Th2(PO4)3
Authors: El-Yacoubi A. , Brochu R. , Serghini A. , Louër M. , Alami Talbi M. , Louër D.
Published: January 2013

A new mixed lead thorium phosphate, Pb0.5Th2(PO4)3, has been isolated in the system PbO–ThO2–P2O5. Its crystal structure (monoclinic symmetry, a=17.459(1) Å, b=6.8451(4) Å, c=8.1438(5) Å, β=101.247(5)°, space group C2/c) has been determined from conventional monochromatic X-ray powder diffraction data. The structure is related to the MITh2(PO4)3 structure type. Lead atoms are located in the channels parallel to the c axis, out of the twofold axis for 0.97 Å, and are statistically distributed on a quarter of crystallographic positions. The thermal stability of this material is greater than that of the monazite-type compound PbTh(PO4)2.
New X-ray powder diffraction data for Fe, B substituted Rb-leucites (RbFeSi2O6 and RbBSi2O6)
Authors: Mazza D. , Lucco Borlera M.
Published: January 2013

The boron and iron for aluminum substitution in the Rb-leucite structure (RbAlSi2O6, ICDD card 38-201) has been examined by sol-gel preparation of different samples along the three compositional joins Rb(X,Y)Si2O6, where X and Y are any two of the elements Al, Fe, B. The compound RbBSi2O6 (a0=12.831 Å) is here described and characterized by X-ray powder diffraction for the first time, while the compound RbFeSi2O6 is reexamined with a more precise determination of lattice parameters and diffraction intensities with respect to ICDD card 31-1189. The lattice parameters and the space groups of different selected terms of the three solid solutions are reported.
Powder X-ray diffraction data for the new polymorphic compound ω-Bi2O3
Authors: Gualtieri A. F. , Immovilli S. , Prudenziati M.
Published: January 2013

ABi2O3compound which is unknown to date has been synthesized at 800 °C on a BeO substrate. α-Bi2O3at 800 °C undergoes a phase transition to a metastable new compound named ω-Bi2O3which in turn transforms to stable δ-Bi2O3at 900 °C. X-ray powder diffraction data were collected, indexed, and refined in order to obtain a unit cell (probable space groupP1¯:a=7.2688(4),b=8.6390(6),c=11.9698(8) Å, α=87.713(6), β=93.227(6), γ =86.653(4)°. This compound is of interest for the thick films circuits and sensors technology.
Calibration of the monochromator bandpass function for the X-ray Rietveld analysis
Authors: Riello P. , Canton P. , Fagherazzi G.
Published: January 2013

In this paper we propose a fitting procedure to describe the bandpass effect on all x radiation that passes through a focusing graphite monochromator used on the diffracted beam. The proposed bandpass function is:M(2θ)=1/(1+Kmon1sKmon2), withs=(2sinθ)/λ, whereKmon1andKmon2are constants which have been refined by means of a Rietveld analysis, using a physically modeled background (Rielloet al., J. Appl. Crystallogr.28, 115–120). We have investigated two polycrystalline powders: α-Al2O3and a mixture of α and β-Si3N4. The so-obtained bandpass functions for these materials are close enough to conclude that they depend only on the used experimental setup (in the present case the X-Pert-Philips diffractometer with a graphite focusing monochromator). Knowledge of the bandpass function is important to suitably model the Compton scattering, which is a component of the background scattering. The present procedure allows one to avoid the direct experimental determination of the bandpass function, which requires the use of another monochromator (analyzer) and another tube with an intense white spectrum.
X-ray characterization of the new nasicon compositions Na3Zr2−x/4Si2−xP1+xO12 with x=0.333, 0.667, 1.000, 1.333, 1.667
Authors: Lucco-Borlera M. , Mazza D. , Montanaro L. , Negro A. , Ronchetti S.
Published: January 2013

It is known that solids with composition Na3Zr2Si2PO12 heated at 1200 °C crystallize in the nasicon structure. This material shows a high ionic conductivity that represents an interesting improvement in the field of solid electrolytes. Our experimental results allow to establish for the first time that nasicon structures are stable along the compositional join Na3Zr2−x/4Si2−xP1+xO12 with x extending from 0 to 1.667. These structures are characterized by a Zr underoccupation of octahedral sites and a constant number of Na+ ions. This fact envisages a possible application of these materials in the field of ceramic sensors and ionic conductors.
Opal, cristobalite, and tridymite: Noncrystallinity versus crystallinity, nomenclature of the silica minerals and bibliography
Authors: Smith Deane K.
Published: January 2013

Cristobalite and tridymite are distinct forms of crystalline silica which, along with quartz, are encountered in industrial operations and industrial products. Because the International Agency for Research on Cancer has designated “crystalline silica” asanIARCGroup 2A (probable carcinogen)and quartz and cristobalite as aGroup 1 (carcinogen), it is important to properly identify and quantify the silica phase in all materials used in production and encountered in products. Opal is a form of hydrated silica which is also encountered in industry. Although some forms of opal mimic cristobalite and tridymite, they are not truly crystalline. The term “silica” in the industrial sense is used to mean any material whose composition isSiO2whether it is crystalline or noncrystalline. Some people also consider silica to include hydratedSiO2. There are many forms ofSiO2which have both long-range and short-range order and are recognized as crystalline phases among which are quartz, cristobalite, and tridymite. The hydrated silicas, on the other hand, pose an enigma. Only a few forms show sufficient long-range and short-range order to be considered crystalline. The mineral silhydrite is an example. Opal in all its forms lacks sufficient order to be considered crystalline. Even opal-C, which produces a X-ray pattern similar to the diffraction pattern of cristobalite, lacks not only sufficient order to be considered crystalline but also contains water in the structural make-up. This paper discusses a classification and nomenclature for these forms which is critical to proper regulation. It also reviews the recent literature on tridymite, cristobalite, and opal, and provides an extensive bibliography. Modern studies have shown that opal-A is disordered, but opal-CT and opal-C contain ordered domains that mimic stacked sequences of cristobalite and tridymite sheets such that X-ray patterns show features similar to the crystalline cristobalite and tridymite. There is debate on whether the ordered regions have lost the water that characterizes the opals. In fact, heating studies have shown that all opals show changes on heating characteristic of materials that lose water in the process. The TEM evidence showing domains in the range 10–30 nm in a matrix of disordered opal suggest that the proper term for this system isparacrystallineanalogous to inorganic and organic polymers.
X-ray powder diffraction data for 2,4-dichloro-5-nitrobenzoic acid
Authors: Quevedo A. Paneque , Novoa de Armas H. , Xuárez Marill L.
Published: January 2013

2,4-dichloro-5-nitrobenzoic acid (C7H3NO4Cl2) has been investigated by means of X-ray powder diffraction. The title compound is monoclinic with unit-cell parameters a=13.761 (2), b=8.435 (1), c=7.684 (1) Å, β=99.85 (1)°, V=878.5 (1) Å3, Z=4, Dx=1.772 g/cm3, space group P21/a (14).
Crystal structure determination of molecular compounds from conventional powder diffraction data: Trimeric silver(I) 3,5-dimethylpyrazolate
Authors: Masciocchi N. , Cairati P. , Sironi A.
Published: January 2013

In the absence of single crystals, silver(I) 3,5-dimethylpyrazolate, [Ag(dmpz)]3, has been structurally characterized byab initioX-ray powder diffraction, using conventional laboratory data. Its crystals are triclinic,P1¯, witha=8.0876(10),b=11.1204(13),c=11.6136(16) Å, α=68.293(6), β=78.350(7), and γ=81.243(6)°. The structure has been solved by Patterson, difference Fourier, and geometrical modeling, and ultimately refined by the Rietveld method down toRp=0.068,Rwp=0.085, andRF=0.055, for 4300 observations in the 17<2θ<103° range. Each molecule consists of a cyclic, trimeric assembly ofAg(dmpz) fragments, with thedmpzligand bridging, in the exo-bidentate mode, nonbonded Ag…Ag edges.
X-ray powder diffraction analysis of a nonlinear optical material 1-benzoyl-3-(4-benzyl)thiourea [N-benzoyl-N′-(4-benzyl)thiourea]
Authors: Jin Zong-ming , Zhou Weiqun , Jin Zheng
Published: January 2013

A nonlinear optical material, 1-benzoyl-3-(4-benzyl)thiourea (C15H14N2OS), has been characterized by X-ray powder diffraction. Experimental values of 2θ corrected for systematic errors, relative peak intensities, values of d, and the Miller indices of 82 observed reflections with 2θ up to 80° are reported. The powder diffraction data have been evaluated, and the figures-of-merit are reported. The least-squares refined unit cell parameters are a=22.0243(6)Å, b=10.9795(7)Å, c=13.0322(8)Å, β=116.88(2)°, V=2810.8(9)Å3, Z=8, Dx=1.278 g/cm3, space group Pn.
Evaluation of the detectability and quantification of respirable crystalline silica by X-ray powder diffraction methods
Authors: Smith Deane K.
Published: January 2013

X-ray powder diffraction is one of the most sensitive methods for the analysis of crystalline forms of silica. In addition to detection and quantification, it can determine the specific crystalline species in the sample. The principal limitations of the method depend on the effective volume of the sample in the X-ray beam and the number of crystallites in the proper orientation to diffract. Detection limits are usually reported as 2 μg in thin-film filter mounts and 0.1% in bulk samples that are free of interference from associated minerals. Filter methods are most often used for air quality monitoring and several standardized procedures have been certified. Standard procedures for bulk samples are difficult to certify because of the variability of the matrices and their potential interferences. All of the methods of quantification require calibration with known samples of quartz or cristobalite. Certification of standard samples involves characterization of the particle and crystallite size and size distribution and amorphous content as well as determining the X-ray diffraction response. Although quartz is readily available and cristobalite is easy to synthesize, preparation of quantities of sufficient uniformity and stability is a limiting factor in certifying such samples for reasonable costs. Conventional diffraction equipment can be used for crystalline silica analysis at the present detection limits required by safety standards. Relatively simple modifications of the diffractometer will increase its sensitivity to small amounts of silica and improve the lower limits of quantification.
Powder diffraction data of BaFCl
Authors: Kesavamoorthy R. , Rao G. V. Narasimha , Sundarakkannan B. , Ghosh G. , Sastry V. Sankara
Published: January 2013

X-ray powder diffraction data of BaFCl are reported for 2θ from 5° to 150° at 25 °C. Strain-free and dendrite-free single crystals of BaFCl, grown by flux method with KCl as flux, were powdered for recording this data. BaFCl is tetragonal, space group P4/nmm, with a=4.3964(1) Å and c=7.2315(3) Å.
1-aminoanthraquinone: Crystal data and a model of molecular packing
Authors: Yatsenko A. V. , Chernyshev V. V. , Aslanov L. A. , Schenk H.
Published: January 2013

The powder diffraction data for 1-aminoanthraquinone at 295 K (P1¯, No. 2, Z=1) are given. The cell parameters found are a=8.205(1), b=8.396(1), c=3.7882(3) Å, α=93.46(1), β=92.57(1), γ=105.13(1)°. The crystal packing model is proposed giving Rb=0.095. The disordered molecule of 1-aminoanthraquinone occupies a special position on the inversion center.
High-resolution X-ray diffraction study of the chromite (Mg0.60Fe0.402+)(Al0.39Cr1.50Fe0.093+)O4
Authors: Fernandes T. R. C. , Langford J. I.
Published: January 2013

As part of a study by high-resolution X-ray diffraction of chrome ores from the Great Dyke, Zimbabwe, powder data are reported for a well-crystallized ferroan magnesiochromite spinel, in which some Cr had been replaced by Al. Data were obtained by using CuKα1 radiation, with an incident beam focusing monochromator to eliminate the Kα2 component. The cell parameter is a0=8.3123(2) Å, the figures of merit are M17=383 and F17=182 (0.0055, 17) and the calculated density is 4.50(5) Mgm−3. A small amount of sample broadening was observed and this was attributed to a mean crystallite size of 259(1) nm. © 1997 International Center for Diffraction Data.
An experimental investigation of the effects of axial divergence on diffraction line profiles
Authors: Cheary R. W. , Coelho A. A.
Published: January 2013

An experimental investigation has been carried out to determine the extent to which axial divergence in a conventional powder diffractometer influences the measurement of peak profile parameters. A Siemens D5000 θ–2θ diffractometer was used for this study along with the LaB6 line profile standard SRM 660. Eight unique levels of axial divergence were investigated either by removing one or more of the Soller slits, or by introducing different combinations of Soller slits in the incident and diffracted beams. The measure of axial divergence used throughout is based on the maximum axial divergences of the incident and diffracted beams, Ψi and Ψd. Axial divergence produces a small and almost constant shift δ2θp in the peak angle which in a typical diffractometer would amount to a zero offset 2θ≈0.005°. The integrated intensity of a profile increases almost linearly with the product Ψi*Ψd. The increase in breadth in profiles in the angular region 2θ<120° arises mainly from the change in asymmetry DH=Hlo−Hhi in which one side of the profile broadens (i.e., either the high angle or low angle side) without any significant broadening of the other side. Moreover, the asymmetry DH is linearly dependent on 2θ for a fixed level of axial divergence, and linearly dependent on the total axial divergence Ψi+Ψd at fixed 2θ.
Synthesis and X-ray powder diffraction data for MNbF6 (M=Fe, Co) compounds
Authors: Goubard Fabrice , Llorente Samuel , Delobbe Valérie , Bizot Daniel , Chassaing Jean
Published: January 2013

X-ray diffraction experiments performed on the compounds FeIINbIVF6 and CoIINbIVF6 have shown that they crystallize in the rhombohedral system, space group R3¯ with a cationic ordering. Unit cell parameters were determined: a=5.4201(8) Å, c=14.072(2) Å, V=357.8(1) Å, Z=3 for FeNbF6, and a=5.351(2) Å, c=13.960(6) Å, V=346.2(2) Å, Z=3 for CoNbF6. Synthesis and powder diffraction data are reported.
Ab initiodetermination and Rietveld refinement of the crystal structure ofBa7Cl2F12
Authors: Es-Sakhi B. , Gravereau P. , Fouassier C.
Published: January 2013

The structure ofBa7Cl2F12has been determinedab initiofrom conventional X-ray powder diffraction data by the “heavy atom” method. The cell is hexagonal (space groupP6¯,Z=1), witha=10.6373(2) Å andc=4.1724(2) Å. Refinement of 38 parameters by the Rietveld method, using 278 reflections, leads tocRwp=0.173,cRp=0.135, andRB=0.054. The structure has common characteristics with that of the otherBaF2-rich fluorochloride,Ba12Cl5F19. In both phasesBa2+ions lie in tricapped trigonal prisms formed by nine halide ions, andCl−ions occupy the center of trigonal prisms ofBa2+ions.F−ions are located in cationic tetrahedra or square pyramids.
Powder X-ray diffraction data for Ba12Cl5F19
Authors: Gravereau P. , Es-Sakhi B. , Fouassier C.
Published: January 2013

Powder X-ray diffraction data for Ba12Cl5F19 are reported. The cell is hexagonal (space group P6¯2m, Z=1), with a=14.0856(3) Å and c=4.2733(2) Å.
Powder diffraction data for fluorocomplexes of niobium IV: MNbF6 (M=Ca, Mg, Cd, Zn)
Authors: Goubard Fabrice , Llorente Samuel , Gaubicher Joël , Bizot Daniel , Chassaing Jean
Published: January 2013

Four compounds in the hexafluoroniobates IV series MNbF6 (M=Ca, Mg, Cd, Zn) have been synthesized by solid-state reactions. CaNbF6, MgNbF6, and the “high temperature” form of CdNbF6 are isostructural with f.c. cubic NaSbF6 (space group Fm3m). ZnNbF6 and the room temperature form of CdNbF6 are isostructural with rhombohedral LiSbF6 (space group R3¯). Syntheses and powder diffraction data are reported.
X-ray powder diffraction data for some nitrogen-donor base adducts of bis(iso-propylxanthato)nickel(II)
Authors: Krausová Dagmar , Trávníček Zdeněk , Ondrůšek Tomáš
Published: January 2013

X-ray powder diffraction data for [Ni(i-prxa)2(bpy)] (1), [Ni(i-prxa)2(phen)] (2), and [Ni(i-prxa)2(tmen)] (3), where i-pr=i-C3H7, xa=S2CO−, bpy=2,2′-bipyridine, phen=1,10-phenanthroline and tmen=N, N, N′, N′-tetramethylethylenediamine, are reported. For (1): Monoclinic, P21/n, a=10.8255(1) Å, b=12.7423(1) Å, c=15.9796(1) Å, β=92.037(3)°, V=2202.9(1) Å3, Z=4, Mr=485.3, T=296 K, DX=1.463 g/cm3, Dexp=1.47 g/cm3, CuKα1=1.540 51 Å, 63 lines. For (2): Monoclinic, P21/n, a=10.7591(1) Å, b=12.8115(2) Å, c=16.1162(3) Å, β=92.39(1)°, V=2219.5(2) Å3, Z=4, Mr=509.4, T=296 K, DX=1.525 g/cm3, Dexp=1.51 g/cm3, CuKα1=1.540 51 Å, 72 lines. For (3): Orthorhombic, P212121, a=9.341(4) Å, b=15.093(8) Å, c=15.990(7) Å, V=2254(2) Å3, Z=4, Mr=445.35, T=296 K, DX=1.312 g/cm3, Dexp=1.32 g/cm3, CuKα1=1.540 51 Å, 49 lines.
Crystal structures and reference X-ray powder diffraction patterns ofSr4−xCaxPb2O8(x=1,2,3)
Authors: Wong-Ng W. , Kaduk J. A. , Greenwood W.
Published: January 2013

The crystal structure of the solid solution alkaline earth plumbate phaseSr4−xCaxPb2O8was investigated using the X-ray Rietveld technique forx=1, 2, and 3. The lattice parametersa,b,c, andVwere found to decrease linearly as the Sr at site 4hwas replaced by Ca. The structure features chains of edge-sharingPbO6octahedra, linked by seven-coordinated (Ca/Sr)–O monocapped trigonal prisms. The structure is similar to that ofPb3O4, which can be reformulated asPb2IIPbIVO4. X-ray diffraction patterns for the solid solution membersSrCa3Pb2O8,Sr2Ca2Pb2O8, andSr3CaPb2O8were prepared for inclusion in the Powder Diffraction File.
The effect of particles on the absorption factor for diffracted X-rays in single-phase powders measured at cylindrical geometry— a computational study
Authors: Collazo J. , Hermann H. , Teresiak A. , Wetzig K.
Published: January 2013

The results of computer simulations of the absorption of diffracted X-rays in single-phase powders measured at cylindrical (or Debye–Scherrer capillary) geometry taking into consideration the size of the powder particles are presented. The samples are simulated by random dense packings of equal spheres. The calculations are carried out for different values of the ratio, Da, of particle size to cylinder diameter, the product, κ, of linear absorption coefficient and cylinder radius and the scattering angle 2θ. Strong deviations of the absorption factor from the values for the ideal case of very fine particles are found in the region 0≤2θ≤30°, and for medium and high values of κ,(κ≥5) and Da (Da≥0.002). The consequences for the experiment are discussed.
Measurement of thermal expansion coefficient of substrate GGG and its epitaxial layer YIG
Authors: Liang Rui-sheng , Liu Feng-chao
Published: January 2013

A new method is used in measuring the linear thermal expansion coefficients in composite consisting of a substrate Gd3Ga2Ga3O12 (GGG) and its epitaxial layer Y3Fe2Fe3O12 (YIG) within the temperature range 13.88 °C–32.50 °C. The results show that the thermal expansion coefficient of GGG in composite is larger than that of the GGG in single crystal; the thermal expansion coefficient of thick film YIG is also larger than that of thin film. The results also show that the thermal expansion coefficient of a composite consisting of film and its substrate can be measured by using a new method.
Reappraisal of the space group of bafertisite
Authors: Yang Zhuming , Cressey Gordon , Welch Mark
Published: January 2013

Bafertisite, Ba(Fe, Mn)2Ti(Si2O7)O(OH, Cl)2, has been reported as belonging to three space groups, i.e., Pmmn, P21/m, and Cm. The samples of bafertisite from the original locality Bayan Obo, Inner Mongolia, and from Jiangsu Province, China, were reinvestigated by X-ray methods. On the basis of single-crystal photographs, Pmmn could be ruled out and the relationship between a subcell in P21/m and the true cell in Cm deduced. The transformation matrix from the subcell to the true cell is 002/02¯0/101¯. Using the X-ray powder data, the refined true unit cell parameters in space group Cm are: a=10.612(3), b=13.637(7), c=12.464(2) Å, β=119.49(2)° for Bayan Obo sample, and a=10.633(6), b=13.67(1), c=12.465(5) Å, β=119.55(4)° for the Jiangsu sample. The 00l-reflections, which are rather prominent due to preferred orientation, can only be explained by our new unit cell.
2-aminophenalenone: Crystal data and molecular packing
Authors: Yatsenko A. V. , Chernyshev V. V. , Schenk H.
Published: January 2013

Powder diffraction data for 2-aminophenalenone at 295 K (P21/n,Z=4) are given, strong lines: 7.54/X, 7.26/9, 3.34/3. The cell parameters found area=3.7213(3),b=16.550(2),c=15.095(2) Å, β=92.61(2)°. The crystal structure was determined using powder data and refined givingRb=0.089. Disordered molecules form stacks along [100] with interplanar spacing of 3.48 Å.
Rigid bodies in powder diffraction. A practical guide
Authors: Dinnebier Robert E.
Published: January 2013

Recipes are given to assist in setting up rigid bodies for common molecules and coordination polyhedra, to define satellite groups, to perform rotations around arbitrary axes through the origin of the rigid body, and to refine intramolecular degrees of freedom under consideration of the special needs of powder diffraction. To the greatest possible extent, the notation follows that of the well known Rietveld refinement program GSAS (Larson and Von Dreele, 1994).
Line broadening in chromites from Zimbabwe using high-resolution X-ray diffraction
Authors: Fernandes T. R. C. , Langford J. I.
Published: January 2013

Chromite grains in ores from the Great Dyke, Zimbabwe, exhibit varying degrees of shearing when viewed by optical microscopy. High resolution diffraction data revealed that line broadening from powder samples of sheared chromites is largely due to two or more spinel phases with slightly different cell parameters, the number of phases increasing with the degree of shearing. The dominant or “parent” phase, with parameters ranging from 8.3123(2) to 8.2676(2) Å, constitutes 57% to 76% of most samples. The cell parameters of secondary phases are generally less than that of the parent phase by δa/a0 in the range −1.3 to −4.0×10−3, the difference again tending to increase with shearing. Most reflections for the parent phase are relatively sharp whereas those for the secondary phases exhibit line broadening that could be analyzed in terms of crystallike (domain) size and rms strain. The crystallite diameters, assuming spherical particles, are relatively large for the parent phases [260(2)–100(5) nm], while those for the secondary phases range from 165(70) to 70(25) nm. The rms strain is not large for any sample and is negligible or small for the unsheared and weakly sheared material. The microstrain in secondary phases is greater than that in the parent phase and tends to increase with shearing, the maximum rms strain being 1.6(3)×10−3. Two new forms of chromite in highly sheared material are reported, one with a slight (0.33%) tetragonal distortion and the other with a cell parameter of 17.561(2) Å, greater than that of normal spinel chromites by a factor of about 3/√2, and a lowering of symmetry from Fd3¯m to Fm3¯m. Changes in chemical composition, indicated by a range in cell parameter, are attributed to tectonics that affected much of the Great Dyke. The strain is partitioned between failure by brittle deformation of the chromite grains and stress-induced cation migration leading to cells with slightly different composition.
A Rietveld-analysis program for X-ray powder spectro-diffractometry
Authors: Xiao Yanan , Hayakawa Shinjiro , Gohshi Yohichi , Oshima Masaharu , Izumi Fujio , Okudera Hiroki , Toraya Hideo , Ohsumi Kazumasa
Published: January 2013

In order to exploit X-ray powder spectro-diffractometry, the program RIETAN-97ß for refining crystal structure and lattice parameters by the Rietveld method was modified extensively. The resulting software can be used to refine anomalous scattering factors, fr and fi, for specified crystallographic sites near the X-ray absorption edge of a particular element. The effectiveness of the modified software was tested by using powder diffraction patterns simulated by the original RIETAN-97ß software and a series of measured powder diffraction patterns of Fe3O4 with incident X-ray energies near the absorption edge of iron.
The combustion synthesis of the ferroelectric material, BaTiO3, studied by time-resolved X-ray diffraction
Authors: Larson E. M. , Wong Joe , Holt J. B. , Waide P. A. , Rupp B.
Published: January 2013

The combustion synthesis of the common ferroelectric material, BaTiO3, was developed using the stoichiometry: BaO2+0.2 Ti+0.8 TiO2→BaTiO3+0.3 O2. An adiabatic temperature, Tad, of the reaction was calculated from known thermodynamic data to be 1917 °C. Real time chemical changes in the formation of BaTiO3 during the reaction have been monitored using time-resolved X-ray diffraction with synchrotron radiation as the X-ray source. A time resolution of 250 ms was achieved. The combustion synthesis of BaTiO3 was followed by observing the intensities of reactant and product Bragg diffraction peaks in order to qualitatively identify the phases present. Because BaTiO3 forms initially as a cubic phase, X-ray diffraction of the product was monitored for a period of 20 min after the reaction to observe the phase transformation to the tetragonal form. This transformation is evident in these post-reaction scans as the cubic 110 and 220 peaks are split to the tetragonal 101/110 and 202/220 ones, respectively.
Crystal chemistry of (RE, A)2M3O7 compounds (RE=Y, lanthanide; A=Ba, Sr, Ca; M=Al, Ga)
Authors: Skakle J. M. S. , Herd R.
Published: January 2013

Phases of general formula (RE, A)2M3O7 (RE=lanthanide, A=Ca, Sr, Ba; M=Ga, Al) are of interest for their nonlinear optical properties and have potential as solid state lasers. Their structures have been refined using X-ray and neutron diffraction data and are related to gehlenite, Ca2Al2SiO7, with M cations occupying Al and Si sites and RE and A cations sharing the Ca site with no evidence for ordering, although they occur in the ratio 1:1 because of stoichiometry; the M cations are tetrahedrally coordinated. (RE, Ba)2M3O7 compounds cannot be synthesized for M=Al or for RE cations smaller than Sm; this limitation is believed to be due to size mismatch between cations within the structure.
New X-ray powder diffraction data for thallium pentaboratesTl[B5O6(OH)4]·2H2OandTlB5O8
Authors: Touboul M. , Penin N. , Seguin L.
Published: January 2013

Precise X-ray powder diffraction patterns of hydrated and anhydrous thallium pentaborates have been collected on a D5000 diffractometer with a primary monochromated beam (λ CuKα1=1.5406 Å). Refinement of indexed reflections led to the following unit cell parameters:a=11.279(1)Å,b=7.1507(6)Å,c=13.953(1)Å, β=94.164(7)° in theP21/cspace group withZ=4,Dx=2.713gcm−3,Dm=2.6gcm−3forTl[B5O6(OH)4]·2H2Oanda=7.5698(5)Å,b=11.9509(6)Å,c=14.759(1)Å in thePbcaspace group withZ=8,Dx=3.844gcm−3,Dm=3.6gcm−3forTlB5O8. Very good Smith and Snyder figures of merit have been obtained:F30=139.7 (0.0043, 50) forTl[B5O6(OH)4]·2H2OandF30=139.3 (0.0054, 40) forTlB5O8.
X-ray powder diffraction data for indium nitride
Authors: Paszkowicz W.
Published: January 2013

X-ray powder diffraction pattern for InN synthesized using a microwave plasma source of nitrogen is reported. The data were obtained with the help of an automated Bragg-Brentano diffractometer using Ni-filtered CuKα radiation. The lattice parameters for the wurtzite-type unit cell are ao=3.5378(1) Å, co=5.7033(1) Å. The calculated density is 6.921±0.002 g/cm3.
X-ray powder diffraction data of anilinium trimolybdate tetrahydrate and anilinium trimolybdate dihydrate
Authors: Rafalska-Łasocha A. , Łasocha W. , Michalec M.
Published: January 2013

The X-ray powder diffraction patterns of anilinium trimolybdate tetrahydrate, (C6H5NH3)2Mo3O10·4H2O, and anilinium trimolybdate dihyhydrate, (C6H5NH3)2Mo3O10·2H2O, have been measured in room temperature. The unit cell parameters were refined to a=11.0670(7) Å, b=7.6116(8) Å, c=25.554(3) Å, space group Pnma(62) and a=17.560(2) Å, b=7.5621(6) Å, c=16.284(2) Å, β=108.54(1)°, space group P21(4) or P21/m(11) for orthorhombic anilinium trimolybdate tetrahydrate and monoclinic anilinium trimolybdate dihydrate, respectively.
Rietveld refinement of the crystal structure of γ-Mo4O11
Authors: Fun Hoong-Kun , Yang Ping , Sasaki Minoru , Inoue Masasi , Kadomatsu Hideoki
Published: January 2013

The crystal structure of γ-Mo4O11 was obtained at room temperature (296 K) by Rietveld analysis with X-ray powder diffraction data. The crystal belongs to orthorhombic system, space group: Pna21, Z=4, Mr=559.753 (Atomic weights 1977), Dx=4.1228 g/cm3, F(000)=1024.0, μ=451.293 cm−1 (Int. Tab. Vol. C, Table 4.2.4.2, p. 193, λ=1.540 60 Å), a=24.4756(5) Å, b=6.7516(1) Å, c=5.4572(1) Å, and V=901.80(3) Å3. The structure was refined to Rwp=5.60%, Rp=4.27%, Rb=3.36%, and Rf=2.74% for 65 parameters with 3541 step intensities and 3055 peaks. Goodness of the fit S=3.35.
X-ray device for continuous in situ electrochemical study of plastic Li-ion cells
Authors: Gérand B. , Blyr A. , Du Pasquier A. , Seguin L.
Published: January 2013

The device developed here for XRD analysis is built on a Guinier–Lenné geometry camera. A monochromatized and focused beam goes through the plastic Li-ion cell protected by a metal–plastic laminate. Each layer of the cell produces diffracted beams that are collected by an X-ray film on the focus circle. The film is continuously moved up (1–2 mm/h) while the Li-ion cell is charged and discharged, and controlled by means of the Mac-pile system. This system allows the control of intercalation rate either in potentiostatic mode or in galvanostatic mode (Mac Pile, Bio-Logic SA, Claix, France). The crystallographic behavior of both plastic electrodes can be simultaneously and continuously observed under the real conditions of a commercial battery. LixNiO2 and C graphite as positive and negative electrodes are given as an example, respectively. Structural and chemical parameters evolving from the two electrodes can easily be correlated with the cycling curves. Studies can also be performed from room temperature up to 100 °C.
X-ray powder diffraction data for ammonium hydrogen (acid) urate,NH4C5H3N4O3
Authors: Tettenhorst Rodney T. , Gerkin Roger E.
Published: January 2013

Crystal and X-ray powder diffraction data are presented for the title compound. The powder pattern was indexed and refined on a monoclinic cell witha=17.356(6) Å,b=3.528(1) Å,c=11.285(1) Å, β=94.23(2) Å. The cell volume andDm=1.772g/cm3giveZ=4. The space group could not be determined with certainty. The planes of the urate anions likely are stacked parallel or nearly parallel to (010).
Crystallographic data of new superlattice phases for spinel LiMn2O4 at low temperatures
Authors: Hayakawa Hiroshi , Takada Toshimi , Enoki Hirotoshi , Akiba Etsuo
Published: January 2013

Extensive analyses of low-temperature powder x-ray diffraction data for spinel LiMn2O4 (Fd3¯m at room temperature) make it clear that two structural phase transitions occur: first around 285 K from cubic to orthorhombic, second around 65 K from orthorhombic to tetragonal. At temperatures under 285 K, superlattice peaks appear in the diffraction pattern that were successfully indexed by tripling the a and b axes of the spinel unit cell. At 250 K, the unit cell is face-centered orthorhombic, Fddd, F2dd, or Fd2d, with a=24.855(1), b=24.755(2), c=8.2014(3) Å, V=5046.1(4) Å3, Dx=4.284 g/cm3, Z=72. The unit cell at 30 K was confirmed to be body-centered tetragonal I41/amd or I41/a, with a=17.5176(3), c=8.1961(2) Å, V=2515.1(1) Å3, Dx=4.298 g/cm3, Z=36.
Milling effects upon quantitative determinations of chrysotile asbestos by the reference intensity ratio method
Authors: De Stefano L. , De Luca F. , Buccolieri G. , Plescia P.
Published: January 2013

As is well known from literature, the grinding process, which is an unavoidable step in sample preparation, may strongly modify the physical properties of chrysotile through amorphisation. The aim of this work is to establish the proper milling time to apply to the samples before an accurate X-ray powder diffraction quantitative analysis. We have used the RIR (reference intensity ratio) analytical method, based on the measurement of the ratio I/Is between the intensity of the strongest line of an analyte and the intensity of the analytical peak of a standard material, when they are thoroughly mixed 50:50 by weight. We have studied how the RIR value changes as a function of the milling time of the sample and how the accuracy of this quantitative method is affected.
Status of the reference X-ray powder-diffraction patterns for the serpentine minerals in the PDF database—1997
Authors: Wicks Fred J.
Published: January 2013

A critical examination of the reference X-ray powder-diffraction patterns of the serpentine minerals in the Powder-Diffraction File (PDF) database has revealed an unsettling situation. Most of the patterns in, or previously in, the PDF database are inaccurate, misidentified, or of poor quality. The PDF database is not a dependable tool for identifying the serpentine minerals, and has not been since the mid-1960s. This has serious implications for studies on serpentine minerals that have depended on the PDF database, particularly those by nonmineralogists doing health and environmental studies of chrysotile asbestos. In the current PDF database, lizardite-1T, carlosturanite, some amesite, and possibly some antigorite (but with inappropriate polytype symbols) can be identified. Only one of the many multilayer lizardites can be identified. The current pattern for chrysotile-2Mc1 (clinochrysotile) is of reasonable quality, but not the best, however the earlier patterns still in the database are so problematic that any chrysotile-2Mc1 identification must be considered suspect. Chrysotile-2Oc1 (orthochrysotile), and any mixture of serpentines cannot be identified using the PDF database. Until the reference serpentine patterns are corrected the PDF database cannot be considered a reliable identification tool. High-quality powder-diffraction patterns of the serpentine minerals have been published and can be rapidly introduced into the PDF database.© 2000 International Centre for Diffraction Data.
Powder X-ray diffraction data for innelite
Authors: Raade Gunnar , Berg Hans-Jørgen
Published: January 2013

X-ray powder data originally published for innelite—Na2Ba3(Ba, K, Mn)(Ca, Na)Ti(TiO2)2[Si2O7]2(SO4)2—were erroneously those of catapleiite. The new data reported here are compared with powder data calculated from the published structure. The cell is triclinic (space group P1, Z=1), a=14.71(1) Å, b=7.115(7) Å, c=5.379(4) Å, α=90.02(7)°, β=94.68(8)°, γ=98.43(9)°, V=555.0(6) Å3, F30=5.2(0.053,109).
Crystal structure of BaBi2Ta2O9
Authors: Paiva-Santos Carlos O. , Mazon Talita , Zaghete Maria A. , Campos André L. , Varela J. A. , Foschini Cesar R.
Published: January 2013

The crystal structure of the Aurivillius compound Bi2BaTa2O9 prepared via the chemical route was determined by direct methods using EXPO97, and refined using the Rietveld method with conventional X-ray diffraction data. The structure was found to be tetragonal (space group I4/mmm, number 139) and Z=2, isomorphic of the Bi2BaNb2O9 reported by Blake and co-workers in the literature (1997). Two refinements were performed using the two asymmetry functions of DBWS-9807 (release 20/May/99). The unit cell for each case are: a=3.932 22(6) Å, c=25.5053(6) Å (RA) and a=3.932 50(7) Å, c=25.5069(6) Å (RCF). The differences for atom positions, interatomic distances and angles are in the range of one standard deviation. Final agreements factors are: Rwp=7.97%, S=1.84, RBragg=4.28%(RA), Rwp=7.98%, S=1.84, RBragg=4.30%(RCF). The occupancies of Ba and Bi in site 2b were refined but constrained to have their summation equal to 1.00. The same constraints were applied to the Ba and Bi of the 4e site. The results show that on site 2b there are 70% of Ba and 30% of Bi and on the site 4e there are 82% of Bi and 18% of Ba. The charge equilibrium is maintained for one standard deviation of the site occupancies.© 2000 International Centre for Diffraction Data.
X-ray powder diffraction data for δ-Na2Si2O5
Authors: Kahlenberg V. , Wendschuh-Josties M. , Fischer R. X. , Bauer H. , Holz J. , Schimmel G. , Tapper A.
Published: January 2013

The X-ray powder diffraction data for δ-Na2Si2O5 are reported. The sample was prepared from water glass solution applied to pressed powder tablets of finely ground quartz using a heating program with a maximal temperature of 700 °C. The crystallographic data for δ-disilicate obtained from a Rietveld analysis are: space group P21/n, a=8.3818(4) Å, b=12.0726(5) Å, c=4.8455(2) Å, β=90.303(5)°, V=490.31 Å3, Z=4, and Dcalc.=2.468 g/cm3.
X-ray characterization of Mg, Fe, and Mn natural end-members of the axinite group
Authors: Salviulo Gabriella , Andreozzi Giovanni B. , Graziani Giorgio
Published: January 2013

New powder X-ray diffraction data for magnesio-, ferro-, and manganaxinite, obtained from samples closely corresponding to the three end-members of the axinite mineral group, were obtained using a conventional Bragg–Brentano diffractometer. Space group is P 1¯. Powder patterns were indexed using Peacock's normal orientation, which gave:a=7.1381(3),b=9.1626(4),c=8.9421(4) Å, α=91.903(4), β=98.105(3), γ=77.468(4)° for magnesioaxinite;a=7.1479(4),b=9.1962(5),c=8.9576(4) Å, α=91.857(4), β=98.177(4), γ=77.359(4)° for ferroaxinite, anda=7.1849(4),b=9.2152(5),c=8.9765(4) Å, α=91.761(4), β=98.153(4), γ=77.150(4)° for manganaxinite. Peacock's orientation has been adopted in all recent structural and crystal chemical studies of axinite, but it differs from that reported on the JCPDS cards (29-344, 27-076 and 27-084, respectively). New data include an increased number of indexed peaks.
Grazing excidence diffraction versus grazing incidence diffraction for strain/stress evaluation in thin films
Authors: Njeh Anouar , Wieder Thomas , Fuess Hartmut
Published: January 2013

The reflection shift δ2Θ caused by a radial shift δrof the sample away from its tangential position at the focusing circle is examined for grazing incidence diffraction and grazing excidence diffraction. Experimental results for residual strain/stress evaluation on thin films using a Bragg–Brentano diffractometer with a grazing incidence equipment are presented. Grazing excidence diffraction is less sensitive to δrthan grazing incidence diffraction.
PULWIN: A program for analyzing powder X-ray diffraction patterns
Authors: Brückner Sergio
Published: January 2013

A computer program is presented that allows for the analysis of powder X-ray diffraction (XRD) patterns. Some peculiar features of the program are: the aptitude for dealing with diffractograms obtained from semicrystalline polymer samples and the ability to evaluate XRD patterns collected with CPS 120 detectors. The program is available as freeware via anonymous ftp at: ftp.cc.uniud.it under the directory/pulwin/.
X-ray powder diffraction data of a new compound As2MoO7
Authors: Hums Erich
Published: January 2013

Arsenic molybdate, As2MoO7, produced by phase transformation of As4Mo3O15, has been analyzed by X-ray powder diffraction. The powder diffraction data were collected with a focusing (Guinier-type) transmission diffractometer equipped with a primary-beam monochromator (Ge 111) for Cu Kα radiation and a scanning position-sensitive detection system. A monoclinic unit cell was determined using an indexing program and compared with calculated single crystal data.
Identification of Crystalline Materials: Classification and Use of X-Ray Diffraction Patterns
Authors: Hanawalt J. D. , Rinn H. W.
Published: January 2013

In the course of the past few years, X-ray and spectroscopic methods of analysis have found an increasing usefulness at the Dow Chemical Company. There are a large number of different types of problems on which information can be obtained by the variations of apparatus and technic which are possible in these two fields. It is not the purpose of this paper, however, to discuss these methods or applications in general, but to describe in some detail a scheme of classifying and using X-ray diffraction patterns which has been found very helpful in one particular application of X-rays — namely, that of identifying unknown substances by means of their Hull powder diffraction patterns.

The inherent power of X-ray diffraction as a practical means of chemical analysis was pointed out a good many years ago. Having a different theoretical basis and depending upon an entirely different technic than other methods, it would be expected to supplement the information to be obtained from other methods and, at times, to be applicable where other methods are not suitable. It appears, however, that the use of this method has not increased at a rate commensurate with its unique and valuable features, and that it is used by relatively few academic and industrial laboratories.
Manual Search/Match Methods for Powder Diffraction in 1986
Authors: Hanawalt J. D.
Published: January 2013

The objectives of this paper are: 1. to up-date the manual search system and index book described in 1936 and 1938; 2. to introduce a “work form” which serves to guide the analyst through the procedural steps involved in using the manual search index book and 3. to review briefly the literature on manual search/match systems.

Two of the basic features of the 1936 design of the search index book were first, to divide the “d” range into arbitrarily sized “groups” and “subgroups” rather than using a scale of continuously decreasing “d” values, and second, to use the “d” values of the strongest lines of the diffraction pattern in order of decreasing intensity in making the entries of the standard patterns in the search index book. These two features are still the basis of the design of the 1986 Hanawalt Search Manual published by the JCPD S International Centre for Diffraction Data.

The original use of the search index book at Dow Chemical was to lead the analyst to corresponding patterns among the thousands of Debye films which had been produced and placed on file. The “d” values and intensities of only the three or four strongest lines of the pattern were measured. Comparisons and indentifications were then made visually simply by holding the concerned films together in juxtaposition. Unfortunately, attempts to reproduce usable copies of such Debye films for general reference have not been satisfactory. Therefore, for general usage the diffraction data carried by the film negative or also the data from a diffractometer trace are recorded using the numerical values of the “d” spacings and intensities. These tables of numerical data are then used to represent the diffraction patterns. The search index book for general usage must therefore deal entirely with these numerical values.