bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical modeling of rigid poly(vinyl chloride) formulations: Fusion characteristics
Authors: Bambrick C. R. , Hoegy L. R. , Ferrari L. P.
Published: May 2005

A central composite design of experiment as used to study the effect of five additives on the fusion characteristics of a rigid PVC compound. The fusion characteristics evaluated were fusion time, fusion torque, and fusion temperature as measured by a torque rheometer. Mathematical models were constructed for the following five independent formulation variables: impact modifier, paraffin wax, calcium stearate, ester wax, and processing aid. Because of differences in the lubricating properties of these additives, mathematical modeling can help the manufacturers of rigid PVC products to understand and better formulate necessary changes to optimizes the performance requirements of their end use products. The ability to predict the fusion characteristics of a proposed formulation change will help minimize the number of required production evaluations.
A viscoelastic interpretation of miscibility for three PVC‐styrenic copolymer blends
Authors: D'Souza Nandika Anne , Letton Alan , Asay R. Elliott
Published: May 2005

The use of multiphase polymers is of growing importance given their inherent economical and technological benefits. Unplasticized PVC is brittle and heat sensitive. Improved impact resistance is often attained by using rubber additives. However, the rubber contributes to increasing viscosity, and, consequently, limited processability. Research efforts are concentrated on the development of a PVC matrix blend that has good heat stability and processability. While traditional PVC modification has concentrated on using plasticizers to aid processing, in this project, the use of three styrenic copolymers has been investigated. Miscibility of the systems has been established using the Rheometrics Mechanical Spectrometer by determining the number of transitions in the resultant blends. Long range time‐temperature effects have been established via generation of master curves for the two component systems. The shift factor data has been analyzed to determine the corresponding activation energies associated with different transitions. These indicate a methodology to design optimum blend systems.
Global markets for chlorine and PVC: Potential impacts of greenpeace attacks
Authors: Goodman Donald
Published: May 2005

Activists in Europe have led the world in criticizing the potential formation of chlorinated organics, including dioxins in the manufacturing of PVC and its feedstocks. The Greenpeace publication “Dioxin Factories” claims that PVC manufacturing is the largest source of dioxins in the world and concludes that all PVC plants should be shut down. The environmentalist argument is that because some unfriendly compounds contain chlorine, all chlorine and chlorine derivative production should be banned. This review analyzes the debate, and using the Charles River Associates and CanTox Reports, comments on what is toxic and what would happen if all chlorine products were taken away.
Experience and advances in automated separation of plastics for recycling
Authors: Kenny Garry R. , Bruner Russell S.
Published: May 2005

A new process system began operation at the Eaglebrook Plastics, Inc. facility in January 1992 that provides automated identification and separation of postconsumer plastic bottles and containers derived from baled and whole bottle sources. Since that time a number of these automated separation systems have been installed, and are in operation. This paper describes automated plastic separation systems that are currently in operation, provides operating data from the plants, and discusses advances in plastic separation methods currently under development.
Plasticizer migration from plasticized into unplasticized poly(vinyl chloride)
Authors: Papakonstantinou V. , Papaspyrides C. D.
Published: May 2005

There exist important industrial applications, such as hoses or plastic windows, dealing with closely combining plasticized and rigid poly(vinyl chloride). Nevertheless, migration of plasticizer causes severe variation of the mechanical performance of the end‐products. This work comprises an effort to investigate and understand these phenomena, also as an extension of previous work of ours in migration to liquid environments. The common system plasticized PVC/dioctylphthalate/unplasticized PVC was studied under two‐sided diffusion conditions, i.e., from a thin sheet of plasticized sheet. The whole assembly was placed between two glass plates and then was held in an oven at 64°C to simulate accelerated test conditions. Some pressure was also applied to ensure perfect contact between the plastic sheets. Three different levels of initial plasticizer concentration (48, 66, and 100 phr) have been considered for a period of about five months, until equilibrium was reached. During this period the migration process was monitored by weight changes. Plots of Mt/M∞ vs. t½, where M∞ the amount migrated at equilibrium and Mt the amount lost at time t, resulted in evident linear relationship. Therefore, it was proved that the Fick's law approximation for short times can be used to describe the migration kinetics for this solid/solid system. On the other hand, macroscopic observations revealed that no plasticizer was accumulated at the interface, i.e. all plasticizer leaving the plasticized sheet entered the rigid ones. Finally, it seems that the controlling stage is the diffusion inside plasticized PVC while possible annealing of the plasticized polymer structure cannot be excluded.
Elastomeric alloys of PVC
Authors: Hein Marc D.
Published: May 2005

The performance standards for flexible PVC compounds continue to become more demanding as manufacturers pursue more value‐added applications traditionally dominated by rubbers and thermoplastic elastomers. Blending of PVC with other polymers has proven to be a viable approach in developing higher performance flexible PVC‐based materials. This paper will review some of the typical approaches to producing PVC‐based elastomers, and show how these standard flexible PVC blends compare to a newly developed family of PVC alloys. The advantages of these materials will be discussed, and some examples of commercial materials and their application will also be reviewed.
International standards for the acquisition and presentation of comparable data on plastics
Authors: Breuer H. , Dean Greg , Tiba M. H. , Shastri R.
Published: May 2005

One of the problems faced by plastics design engineers, in addition to anyone involved in resin selection in new product development, is access to comparable data among similar products from different material suppliers. This stems from the lack of standardization in the acquisition and reporting format for materials properties data in the plastics industry. Currently, a multiplicity of national test standards is widely used in the acquisition of the data, which often allows a broad flexibility in the choice of test specimen shapes and geometry, conditions for preparing the test specimens, test variables, and test conditions, in addition to units, rendering any comparison between materials extremely difficult. ISO 10350 and 11403, Parts 1, 2, and 3, were developed specifically to address these issues for the acquisition of the data, and the CAMPUS database was developed as a tool for standardization of the reporting format for plastics properties. The real driving force for standardization at the international level is the growing need for comparable data on a global basis because of the emerging global nature of the manufacturing industry and the cost savings. This paper will discuss the rationale, driving forces, and the status of the worldwide standardization efforts, along with the benefits and experience gained to date.
Predicting surface defects in injection molded PVC components
Authors: Weir Scott
Published: May 2005

Surface defects in injection molded PVC parts have long been analytically unpredictable. These defects are typically caused by thermal instability and flow instability of the material. There exists a need to analytically predict these defects through the use of mold filling simulation. This paper documents an experimental approach to predicting surface defects on injection molded PVC parts through the use of material characterization, mold filling simulation correlation, and verification tests.
Studies of molecular weight distribution, particle morphology, and rheological behavior of ultra‐high molecular weight suspension PVC
Authors: Hua Youqing , Huang Yiqun , Siqin Dalai
Published: May 2005

In this paper, the particle characteristics and rheological behavior of ultra‐high molecular weight PVC (UHMWPVC) produced in both Japan and mainland China were studied. The molecular weight and its distribution of UHMWPVC were measured by GPC. By means of a series of techniques such as SEM, the measurement of surface pore size, plasticizer absorption, and photographic analysis, the morphology and general characteristics of UHMWPVC particles were investigated. A model of particle structure was proposed. It was found that compared to general PVC, UHMWPVC resins are more porous, having better plasticizer absorption properties. Similarly, compared to UHMWPVC made in mainland China, UHMWPVC made in Japan possesses particle characteristics preferred in PVC processing. In the studies of rheological behavior, the programmed temperature Brabender torque rheometer was used to study and compare the melting process of UHMWPVC resins and their plasticized systems under the same shear stress. The capillary rheometer and Brabender extrusion‐rheometer were applied to investigate the rheological and extrusion properties of the plasticized systems mentioned above. The results showed that in melting and extrusion process, the particle characteristics of UHMWPVC result in the easy breakage of particles and the formation of “molecular flow,” On the other hand, the high molecular weight is unfavorable to processing. Generally speaking, much more research work is needed to improve the flow properties of UHMWPVC.
Present status of sorbitol Hexa‐acetate as an X‐Ray monochromator
Authors: Jenkins R. , Croke J. F. , Westberg R. G.
Published: May 2005

Sorbitol hexa‐acetate (SHA) crystals are now available which, in comparison with those previously grown, are at least an order of magnitude better for the reflection of Mg Kα radiation. Although the new crystals are still only half as good, in terms of absolute peak intensity, as ammonium dihydrogen phosphate (ADP), freedom from background interferences and better long term reproducibility should make SHA a reasonably attractive alternative to ADP.
X‐Ray fluorescence applied to the on‐stream analysis of sulphide ore fractions
Authors: Reed D. J. , Gillieson A. H.
Published: May 2005

Factors affecting the on‐stream analysis of sulphide ore slurries have been investigated for a number of copper‐zinc ores. Zinc, copper and iron were counted on streams of various solids contents, but, because of equipment limitations, sulphur was determined by calculation and the gangue, regarded as silica, by difference.

Two simple correction factors were used: the ratio of Rayleigh scatter from the stream under investigation to that from water was found to vary as the cube root of the per cent solids in the stream, and the product of two ratios was adequate to relate the intensity of the characteristic radiation from streams of other solids contents to a 30 per cent stream which was used as a reference in this work. These factors made it possible to calculate the zinc, copper and iron in the solids fractions of ore slurries with an accuracy adequate for the control of sulphide ore beneficiation processes.

No inter‐element effects were noted, but a marked matrix effect made it necessary to use different correction factors and regression lines for the metals in ore concentrates and in heads and tails.
X‐ray fluorescence analysis applying theoretical matrix corrections. Stainless steel
Authors: De Jongh Willy K.
Published: May 2005

The conversion of X‐ray fluorescence intensities to concentrations by a mini‐computer requires simple equations for routine use. The influence coefficients, accounting for inter‐element effects in homogeneous samples, are calculated from fundamental parameters by means of a programme called ALPHAS operating on a large computer. These coefficients can subsequently be used in the simple routine equations for wide range calibration. The theoretical coefficients are a valuable support for wide range calibrations using multiple regression analysis. The number of required standards is significantly reduced. The exclusive use of theoretical influence coefficients is demonstrated for stainless steel.
Theoritical alpha coefficients for the Claisse‐Quintin relation for X‐ray spectrochemical analysis
Authors: Rousseau R. , Claisse F.
Published: May 2005

Mathematical equation are given for calculating the theoritical values of α coefficients in the Claisse‐Quintin relation for any combination of elements and experimental conditions. The Claisse‐Quintin relation becomes an approximation of the Sherman equation with minor deviations.

The method can be extended to electron microprobe analysis.
The analysis of slags from primary and secondary copper smelting processes by X‐ray fluorescence
Authors: West N. G. , Hendry G. L. , Bailey N. T.
Published: May 2005

A method for rapid and accurate X‐ray fluorescence analysis of a wide variety of slags from the copper producing industries has been developed. The samples are fused in a sodium tetraborate + lanthanum oxide flux with sodium nitrate added to ensure oxidizing conditions in the melt. Nine elements have been investigated, namely Cu, Zn, Fe, Si, Al, Pb, Sn, Ni and S. It has been found that simple linear calibrations give accurate results for most elements, but in the case of Cu, Zn, and Ni a correction procedure based on secondary mass absorption coefficients may sometimes be necessary.
An X‐ray fluorescene technique for the analysis of lead in gasoline
Authors: Larson J. A. , Short M. A. , Bonfiglio S. , Allie W.
Published: May 2005

A technique has been developed for the measurement of lead in gasoline in the range 0.002 to 5 g/U.S. gal. The method is based on the use of Campton Scattering as an internal standard, and on a comparison of the unknown with a blank and with a standard solution. A correction procedure has been devised which takes into account the dependence of the analysis on the carbon‐hydrogen ration of the gasoline. The method has an accuracy, for a single measurement, of ± 0.002 at the 0.002 g/U.S. gal. level to ± 0.1 at the 5 g/U.S. gal. level.
Determination of a binary calibration curve with one or two standard specimens in X‐ray flourescence analysis
Authors: Kähkönen H. , Suhonen P.
Published: May 2005

Two simple approximate formulae have been derived for binary calibration curves. These formulae contain one or two constants, which can be determined experimentally with one or two standard specimens, respectively. These formulae can be applied within a wide range around the composition of the standard specimen. These approximations can be used both in X‐ray and in isotope excited fluorescence analysis.
A mathematical model for tertiary X‐rays from heterogeneous samples
Authors: Dunn William L. , Efird Carl R. , Gardner Robin P. , Verghese Kuruvilla
Published: May 2005

A mathematical model is derived for tertiary X‐ray fluorescence from heterogeneous samples based on generally accepted primary X‐ray fluorescence models. Variable source‐sample‐detector geometry, sample particle size and packing fraction effects are included. The model is expressed explicitly for three different ways of treating the attenuation within the sample. Calculations of the model are made for comparison with primary and secondary fluorescence calculations, and for comparison with calculated and experimantal results reported in the literature which include tertiary effects.
On the use of an electron spectrometer as detector for soft X‐ray spectra
Authors: Ebel Maria F.
Published: May 2005

A combination of a soft X‐ray source with an X‐ray photoelectron spectrometer as a detection system gives very good resolution of the spectra. The use of a solid converter (gold) is discussed in comparison with gaseous converters. Good detection efficiency is accompanied by an increased background distortion of the lineshapes and occasionally line interferences. Solutions to these problems are described, as well as an example of analytical application. Finally, a windowless arrangement for the detection of ultrasoft X‐rays is proposed.
Rapid quantiative analysis of some rare earth oxides in inorganic glasses by means of energy dispersive X‐ray measurement in a scanning electron microscope
Authors: Blum F. , Res M. A.
Published: May 2005

This paper deals with the quantitative analysis of neodymium, erbium and ytterbium oxides in borate, silicate and tellurite glasses by means of energy dispersive X‐ray analysis in a scanning electron microscope. The problem of the deconvolution of overlapping intensity peaks is discussed and calibration curves for rare earth oxides in the different base glasses are established.
Measurement of oxygen K absorption spectra using an electron microprobe
Authors: Norrish K. , Smith D. G. W.
Published: May 2005

A technique is outlined which use the electron microprobe to obtain X‐ray absorption spectra, by photon absorption, in the long wavelength region. Spectra are presented for SiO, SiO2, rectorite, talc, vermiculite, V2O5, Cr2O3, Fe2O3, maghemite, Mylar and collodion. For all compounds the main absorption edge is near to 536 eV, which is significantly higher than core binding measured in ESCA studies. The transition metal oxides and organic films show a sharp absorption line near 531 eV in addition to the above edge. This absorption line is very close in energy to the anomalous peak observed in the oxygen K emission spectra when using KAP or other acid phthalate crystals and it seems likely that the two phenomena are associated.
Determination of the X‐ray mass absorption coefficient by measurement of the intensity of Ag Kα compton scattered radiation
Authors: Franzini M. , Leoni L. , Saitta M.
Published: May 2005

By utilizing a reflection geometry, an accurate mass absorption coefficient of a sample can be determined by measuring the Ag Kα Compton intensity. Intensities of Ag Kα Compton scattered radiation have been collected by using either the usual reflection geometry of a Philips PW 1450 automatic X‐ray spectrometer or a more refined reflection geometry, achieved on a Philips PW 1540/10A manual X‐ray spectrometer. The experimental results have shown that the relationship between the Ag Kα Compton intensity and the mass absorption is a logarithmic function. Our experimental results are not in agreement with those reported in literature, but a theoretical explanation to account for this fact has not been achieved as yet.
Concerning the obtaining of effective influence coefficients for X‐ray spectrometric analysis
Authors: le Sage R. Vié , Tertian R.
Published: May 2005

As a consequence of our previous study of equivalent wavelength variations, the so called equivalence relationship between absorbers allows a ready calculation of the influence coefficients of any absorbing element simply from the knowledge of the situation with one particular element. This simple procedure is discussed and then illustrated using the case of iron fluorescence as an example. It is considered particularly advantageous when practising accurate experimental calibration because it yields effective influence coefficients, i.e. that coefficient variation, as well as the particular geometry and spectral intensity distribution of the equipment being used are automatically accounted for. In addition, this method is liable to save much time and notably simplify the requirements for standards.
A description of two automated control systems for the electron microprobe
Authors: Frost M. T. , O'Hara K. , Suddaby P. , Grant G. , Reid A. F. , Wilson A. F. , Zuiderwyk M.
Published: May 2005

Control systems for a Geoscan microprobe based on a minicomputer with a core of 4 K of 16‐bit words and for a Japan Electron Optics Laboratory JEOL JXA‐50 with a minicomputer having 16 K words are described in general terms. Similar analysis strategies are used in both systems, but the Geoscan software operates on a ‘stand‐alone basis’ while that for the JXA‐50 is based on a modified version of an Interdata operating system, supporting an interactive program for flexible operator control of the probe. Lower initial cost and less programming effort were involved in the Geoscan control system, but this is balanced in the larger JXA‐50 installation by greater flexibility and ease of operation.

The integration of non‐dispersive X‐ray detector systems with microprobe control systems, the suitability of the software operating system for incorporation of such devices and for extension to digital beam scanning and particle area analysis are also briefly considered.
The application of a multichannel chart recorder to energy‐dispersive analysis in the scanning electron microscope
Authors: Sharp R. M.
Published: May 2005

This paper describes a recently developed multichannel chart recorder and shows how it can be applied to the display of data from the scanning electron microscope energy‐dispersive analysis system. Advantages and limitations are outlined. The advantage of the recorder is that it provides hard‐copy data with extremely fast analysis times. A limitation is that the system is only semi‐quantitative. Three applications in which the use of the recorder has proved advantageous are described: the fields of metallurgy, mineralogy and forensic science.
Analysis of plant material by X‐ray fluorescence spectrometry
Authors: Mudroch A. , Mudroch O.
Published: May 2005

To get a better understanding of chemical changes accompanying reproduction, maturation and senescence of plants, plant samples collected in various marshes were analysed by X‐ray fluorescence spectrometry for Na, Mg, Al, Si, P, K, Ca, Ti, Mn and Fe with sufficiently accurate results. The preparation of pellets from unground, coarse and finely ground plant material was investigated and no significant difference was found in X‐ray count rates. A computer program was developed for routine analyses of plant material using NBS standard Orchard Leaves.
Experimental comparison of photon‐and particle‐induced X‐ray emission analysis of air particulate matter
Authors: Ahlberg M. S. , Adams F. C.
Published: May 2005

Energy‐dispersive X‐ray fluorescence analysis (XES) using secondary fluorescers of Ti and Mo is compared with particle‐induced X‐ray emission analysis (PIXE) using protons of 2.3 MeV and 5.0 MeV for the analysis of air particulate matter. Experimental detection limits are derived from the analysis of an impactor sample collected on Whatman‐41, Millipore AAWP, and 0.4 μm Nuclepore filters and from the analysis of an impactor sample on a Mylar foil from stage 4 in a 5‐stage single orifice cascade impactor. The detection limits are compared using the criterion of equal number of counts in the spectra. PIXE is shown to give about three times lower detection limits for the filter samples and about 30 times lower limits for the impactor sample. The conclusions to be drawn from this and other aspects on the difference between XES and PIXE in the analysis of aerosol samples are thoroughly discussed and the results are extrapolated to the analysis of other environmental samples.
The Bragg reflection integral for pentaerythritol
Authors: Hall Ray , Lewis Margaret , Leigh Bryan , Evans Kenton
Published: May 2005

Pentaerythritol is, for a number of given reasons, notable among the relatively limited choice of materials suitable for the manufacture of Bragg X‐ray analysers for use in quantitative X‐ray spectrometry to relatively long wavelengths. In many, perhaps most, Bragg X‐ray optical systems the beam power throughput to the detector, and hence the system sensitivity, is directly proportional to the Bragg reflection integral. Absolute beam power spectrometry thus requires knowledge of the wavelength function of that quantity for the analyser used. In this paper the nature of that function, and its stability, is investigated for diffraction from the (002) planes of pentaerythritol.
A non‐linear least squares fitting routine for optimizing empirical XRF matrix correction models
Authors: Schreiner W. N. , Jenkins R.
Published: May 2005

An off‐line non‐linear least squares fitting procedure is described as part of a program package ‘RUNFIT’. This program supports most of the intensity/correction algorithms currently employed in X‐ray fluorescence spectrometry. The program runs under the Data General DOS operating system and requires a minimum hardware configuration of 32K 16 bit words and two floppy disks. The minimization technique is based on the Marquardt scheme which has the main advantage that the step direction taken in the minimization process always lies in the direction of steepest descent. The RUNFIT program includes various statistical tests on the fitted data which enable the user to make accurate judgements as to the quality of the fitted data. Several examples are given of the use of this approach to typical analytical situations.
The family of alpha coefficients in X‐ray fluorescence analysis
Authors: Lachance G. R.
Published: May 2005

The demand for comprehensive analysis of materials by XRF using automated instrumentation has led to increasing use of the coefficient approach for dealing with the ever‐present interelement effect. A survey of the literature shows that this has often led to a multiplicity of families of calibration curves being replaced by a multiplicity of tables of correction coefficients. A practical approach is outlined which facilitates the recognition of (a) the alpha subset of influence coefficients, and (b) three related subsets of alpha coefficients – basic, modified and hybrid. This mobility of alpha coefficients (alloys, oxides, fusions, solutions) coupled to their adaptability (geometry, primary radiation) and accessibility (theoretical, experimental) has wide implications. It permits a consolidated view of the influence coefficients, and comparison of the sign, magnitude and pattern of basic alphas so as to establish if and when there is consensus. The confirmed alpha coefficients thus obtained can then be transferred with confidence to suit specific operating conditions and methods. Examples are given using data that have appeared in XRF literature.
Studies of the non‐linear rise in intensity if x‐ray line
Authors: Das Gupta K. , Bahgat A. A. , Seibt P. J.
Published: May 2005

A non‐linear rise in intensity of copper Kα1 and Kα2 X‐ray lines has been observed from certain areas of the polycrystalline copper target of a microfocus tube operated at tube currents between 0.1 and 0.5 mA and a tube potential of 13 kV. Under the same conditions the intensity rise of the bremsstrahlung is found to be linear. A functional relationship between total count and tube current has been obtained.
Photon‐Induced x‐ray fluorescence determination of platinum in reforming catalysts and doped venezuelan laterites
Authors: LaBrecque J. J.
Published: May 2005

A non‐destructive method for the determination of platinum in reforming catalysts and doped Venezuelan laterites employing a radionuclide, 8mCi of 109Cd, and a PDP‐11/05 processor is presented. The total variation for 100s of fluorescent time is about 3% for a 10% Pt‐reforming catalyst. The total variation can be reduced to less than 1% by increasing the fluorescent time so that about 80 000 counts or greater are accumulated. The platinum was determined using the Lα and Lβ lines of platinum, as well as their sum. The different types of variation for each of these measuring parameters is given. Finally, both the calculated and measured values for the prepared calibration standards and the doped Venezuelan laterites were in excellent agreement.
The discrimination and classification of small fragments of window and non‐window glasses using energy‐dispersive x‐ray fluorescence spectrometry
Authors: Dudley R. J. , Howden C. R. , Taylor T. J. , Smalldon K. W.
Published: May 2005

Fifty pairs of window/non‐window glasses, the samples in each pair being matched in refractive index to the fourth decimal place, have been analysed using energy‐dispersive X‐ray fluorescence spectrometry. The spectra, from 200μg fragments, were compared using a computer based multi‐dimensional data processing system. Forty‐three pairs of glasses were readily discriminated and forty‐nine pairs showed significant differences at about the 5% level. The spectral data for the 100 glass samples were then examined graphically for trends in the elemental levels between the window and non‐window glasses. This led to the construction of two linear combinations, namely the peak area ratio (to calcium) of iron with that of magnesium and the peak area of arsenic with refractive index. When plotted against each other these linear combinations and a selection rule allowed 95% of the glasses to be correctly classified.
X‐ray fluorescence analysis without standards
Authors: Mantler M. , Ebel H.
Published: May 2005

Theory and experimental results from X‐ray fluorescence analysis without standards are presented. The composition of an unknown specimen is calculated from its count rates without the use of standard specimens. A fast algorithm employing linear approximation techniques uses these normalized count rates as start values for the concentrations and delivers final results usually after the second or third iteration. Accuracy is typically around 10% relative and can be improved by system calibration with standards of arbitrary composition.
Experimental evaluation of the Rhodes–Hunter model for the particle size effect in X‐ray fluorescence analysis of ‘thin’ samples
Authors: Hołyńska Barbara , Markowicz Andrzej
Published: May 2005

The experimental evaluation of the Rhodes–Hunuer model of the particle size effect in X‐ray fluorescence analysis of ‘thin’ and monolayer samples is reported. The calculations and experiments were carried out for samples of iron oxide(Fe3O4) and copper sulphide (Cu2S) having particles of one size and a histog am distribution of particle sizes. For iron oxide particles, it was found that sticking causes a significant systematic discrepancy between the experimental results and the Rhodes–Hunter model prediction. For copper sulphide particles the model was applicable.
A theoretical procedure to determine coefficients from the Rasberry–Heinrich calibration curve in XRF spectroscopy
Authors: Mainardi R. T. , Fernández J. , Bonetto R. , Riveros J. A.
Published: May 2005

Relative X‐ray fluorescent intensity data have been generated numerically for binary samples under mono‐chromatic excitation in those cases of absorption plus enhancement that are dealt with in this work. These data were fitted to the empirical Rasberry–Heinrich equation, keeping both coefficients different from zero, since from our numerical calculations it is shown that in most cases the best fit is achieved when A ≠ 0. Furthermore, this approach shows that a third coefficient introduced into the empirical equation improves the fitting. The aforementioned results suggest that the empirical equation could be deduced from the theoretical equation of fundamental parameters under suitable approximation. The result is an equation similar to that of Rasberry and Heinrich, from which analytical approximated coefficients are obtained. It is then possible to calculate a calibration curve using fundamental parameters values.
Application of scanning electron microscopy in the analysis of the 2:1 group of clay minerals: Vermiculite
Authors: Patel M.
Published: May 2005

Various pretreatments required for analysis of vermiculite minerals by scanning electron miscroscopy are described. It is shown that lyophilized samples exhibit more characteristic and reproducible micrographs than when simply dried in air. The mineral should e preheated in vacuum at 150°C to aviod the risk of exfoliation. In view of the fragile structure of clay minerals, polishing of the solid is to be avioded.
Chemical effects on X‐ray K emission spectra of calcium in various compounds
Authors: Yasuda S. , Kakiyama H.
Published: May 2005

A systematic investigation of the chemical effects on the calcium X‐ray K emission spectra from 32 chemical compounds was carried out using a two‐crystal X‐ray spectrometer. The observed chemical shifts of the Ca Kα1,2, Kα3,4, Kβ1,3 and Kβ5 lines relative to the respective lines from CaF2 varied in the range +0.06 to +0.30, +0.09 to +0.32, −0.06 and +1.1 to +3.2eV, respectively. A certain dependence on the nature of surrounding groups was found in these shifts. The profile changes in the Ca Kβ5 and Kβ bands from all compounds were discussed by subdividing them roughly into three types, depending upon their characteristic features.
A Gaussian expression to describe ϕ(ρz) curves for quantitative electron probe microanalysis
Authors: Packwood R. H. , Brown J. D.
Published: May 2005

It is shown that the depth distribution of X‐ray production in the electron microprobe can be accurately described by a Gaussian modified at the sample surface by a transient. Assuming that the Gaussian is a consequence of the electrons undergoing a random walk in the sample and that the transient corresponds with the change from collimated to random electron trajectories enables theoretical values for the amplitudes and coefficients of the two functions to be predicted. There is excellent agreement between the predicted and the observed values. The Lenard coefficient and the electron range can both be estimated from the coefficient in the Gaussian. It is suggested that for microprobe work, Lenard's law for electron absorption be replaced by this revised law. Both the absorption and atomic number corrections of the traditional ZAF approach are replaced by the new function.
Matrix effects in the x‐ray fluorescence method
Authors: Kuczumow Andrzej , Rzaçzyńska Zofia , Szewczak Marek
Published: May 2005

The matrix effects which exist in x‐ray fluorescence analysis are considered, Shiraiwa and Fujino equations being the initial point of these considerations. Matrix effects are divided into two groups: simple and so‐called unusual. Among the simple ones, absorption and enhancement effects are considered. New concepts of ‘absolute’ and ‘relative’ absorption effects are introduced. It is shown that the expressions of simple matrix effects can be easily separated in the Shiraiwa and Fujino equation. Additionally, the unusual matrix effects, including the Birks‐Harris effect and some cases of the Mitchell‐Kellam effects, were found to be well described by certain equations based on the Shiraiwa and Fujino equation, provided the appropriate assumptions were made.
Quantitative electron probe microanalysis using Gaussian ϕ(ρz) Curves
Authors: Brown J. D. , Packwood R. H.
Published: May 2005

The Gaussian expression for ϕ(ρz) has been used as the basis of a computer program for quantitative electron probe microanalysis. Corrections for absorption and atomic number are combined within the expression for ϕ(ρz) whereas the fluorescence correction is based on numerical integration over the primary and secondary intensities. Error histograms based on about 500 published analyses of standard specimens have been used to adjust the parameters in the Gaussian expression for optimum accuracy. The resultant error histograms are as narrow as those obtained for the most accurate of the current ZAF correction procedures. Extension of the method to non‐normal electron incidence is relatively straightforward.
Quantitative x‐ray fluorescence analysis by use of fundamental influence coefficients
Authors: Broll N. , Tertian R.
Published: May 2005

The rigorous relationship existing between effective fundamental coefficients, as expressed by Tertian's identities, and Sherman's basic equations for x‐ray fluorescence intensities is recalled. The properties of these coefficients in the case of binary systems are described, for usual as well as for some anomalous situations, and a general, accurate hyperbolic equation is suggested to account for coefficient variation with composition. The properties of effective coefficients in the general case of multicomponent systems (alloys, etc.) are then examined, and illustrated on the typical FeNiCr ternary system, confirming the essential exactness of this approach. As a consequence, the authors propose to make use of calculated effective coefficients to apply mathematical matrix corrections, and give a first outline of the analytical procedure.
Determination of composition and thickness of TiNxOy films on silicon by combined x‐ray and nuclear microanalysis
Authors: Armigliato A. , Garulli A. , Rosa R. , Berti M. , Drigo A. V. , Desalvo A.
Published: May 2005

The stoichiometry and thickness of TiNxOy films has been determined by electron microprobe and nuclear microanalysis. The difficulty arising in the electron microprobe from the interference between NKα and TiLI lines has been overcome by using a suitable Monte Carlo computing scheme. This procedure takes into account the SiKα intensity which was found to be sensitive to composition and thickness of the overlying TiNxOy film. The good agreement between electron microprobe and nuclear microanalysis results indicate the validity of the method.
X‐ray fluorescence analysis with a linear polarized beam after bragg reflection from a flat or a curved single crystal
Authors: Wobrauschek P. , Aiginger H.
Published: May 2005

Improvements of the detection limits in photon induced x‐ray fluorescence analysis are obtained by the reduction of the radiation background using linear polarized x‐rays for excitation. A single crystal where Bragg reflection takes place at an angle 20 = 90° produces linear polarized and monochromatic x‐rays. The use of a single crystal instead of amorphous scattering materials increases the intensity of the polarized beam in some cases up to a factor 104. The use of curved crystals instead of standard flat crystal geometries shows a further increase in the intensity of the exciting beam in the focus line. The crystals in use for both geometries are described. Samples can be investigated in either form, liquid or solid, no special preparation technique is required. Detection limits are given for some elements, absolute amounts of 150 picogram can be detected in some cases.
Properties of intrinsic germanium detectors at low engergies by escape peak spectroscopy
Authors: Rosner B. , Mingay D. W.
Published: May 2005

The study of the energy resolution and linearity of germanium, x‐ray detectors at very low energies is difficult due to the degradation of the spectral line shapes resulting from incomplete charge collection in the detectors's surface dead layer. The use of low‐energy, K escapes peaks obviates this difficulty as they are absorbed at depths characteristic of their full‐energy parent photons. Measurements have been performed using particle‐induced x‐ray emission analysis of targets having characteristic K and L x‐ray energies just above the Ge K‐edge. The escape peaks retain pure Gaussian shapes down to the noise level of the detector and open up the possibility of a selective field of high‐resolution escape‐peak spectroscopy.
Application of the linear relationship between the reciprocal of analyte‐line intensity and the reciprocal of concentration to the analysis of geological materials
Authors: Huang Chung‐Hsi , Smith T. E.
Published: May 2005

The linear relationship between the reciprocal of analyte‐line intensity, and the reciprocal of concentration has been applied to the determination of ten major and minor elements in silicate rocks and minerals. The analyses were carried out on fused specimens of 11 rock standards, with and without added La2O3, and with and without added NaNO3. The method requires no absorption matrix effect corrections, and is ideally suited to the analysis of geological materials with a wide range of chemical composition. It clearly has the advantage of simplicity and speed, and can be applied to the analysis of samples when suitable standards are not available. The results obtained in all cases are in excellent agreement with the literature. However, the discs with La2O3 added yield results with better precision and accuracy than do those without La2O3. Na2O is normally determined on separately prepared rock powder pellets, but can be satisfactorily analysed by this method, using the La2O3 added discs, together with all of the other major and minor elements. Na2O analyses are more readily obtained using discs without added NaNO3. We, therefore, recommend that the analysis of geological materials be carried out on fused glass discs with La2O3 added and without NaNO3.
Limitations in the use of the peak‐to‐background method for quantitative analysis
Authors: Rez Peter , Konopka John
Published: May 2005

The use of peak‐to‐background ratios has been suggested for the analysis of particles or rough surfaces as the peak‐to‐background ratio is assumed to be independent of geometry. The validity of this assumption is examined for flat specimens. It is shown that the peak‐to‐background ratio does not vary much with sample orientation but does vary with voltage, tending to a limit at high voltages. Methods of analysis using the peak‐to‐background ratio are proposed and the effects of fluorescence are discussed.
Proton and photon‐induced x‐ray fluorescence intensity from a monolayer sample of complex chemical and granular composition
Authors: Volkov V. F. , Krasnopolskaya N. N.
Published: May 2005

A probability method is used to describe the processes of characteristic x‐ray fluorescence excitation and absorption in a heterogeneous monolayer of particles. Based on this the analytical dependence of the characteristic x‐ray peak intensity on the sizes and shape of particles, and the distribution of elements among the particles is inferred, for two kinds of spectrum excitation. Theoretical evaluations for applying boundaries of the ‘thin’ homogeneous layer model to a heterogeneous monolayer are given. The elements to be determined in unknown compositions are S, Fe and Pb.
Trace element analysis of silicates by means of energy‐dispersive x‐ray spectrometry
Authors: Johnson Robert G.
Published: May 2005

Three methods for the energy‐dispersive x‐ray spectrometric analysis of trace elements in silicate rock samples were compared. The comparisons were based on three new USGS reference samples, DNC‐1, W‐2, and BIR‐1, and two established reference samples, G‐1 and W‐1. A loose powder sample preparation was used in the analysis of selected trace elements, including Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb and Ba. For one method, the ratio of analyte line intensity to either Compton or Compton and Rayleigh scatter intensity for a series of standards was used to construct calibration graphs. The other two methods involved fundamental parameter calculations which required a knowledge of the total sample compositions in order to perform the necessary matrix corrections. The results showed good accuracy for all three methods, but those obtained from the ratio–calibration graph method were slightly better than those from the other two methods.
Method of spectral background evaluation using higher energy peaks in x‐ray energy analysis
Authors: Cirone R. , Gigante G. E. , Gualtieri G.
Published: May 2005

A method for spectral background evaluation in x‐ray energy analysis is proposed, based on a simple model of background generation in the detector. This model assumes that photons, of a given energy, interacting with the detector have probabilities of generating background counts within lower energy windows. The usefulness of the method resides in the fact that it allows a background evaluation with different levels of complexity and accuracy. The method also permits accurate background calculation with samples of variable mass and composition, such as biological and environmental materials.
Sub‐surface charging, a source of error in microprobe analysis
Authors: Graham J. , Butt C. R. M. , Vigers R. B. W.
Published: May 2005

Qualitative microprobe analysis of sodian potassian hydroxonian meta‐autunite failed to reveal any sodium, although nearly 3% was present. Potassium, magnesium and calcium were underestimated to a smaller extent in related natural and synthetic structures. The effect is due to the migration of these interlayer cations from the analysed region—almost instantaneously in the case of sodium—and a consequent decrease in count rates, under the influence of the space‐charge resulting from the incident electron beam. Experiments with the autunites and with a soda‐glass subjected to various coating treatments showed that the effect of charging can be dramatic. Such charging also occurs when alkali metals are not present, a fact which has important implications for all microprobe analyses.
K‐absorption edges of cobalt in its metallic soaps and their liquid crystalline solutions in benzene
Authors: Nigam Amar Nath , Rajput Om Prakash , Srivastava B. D.
Published: May 2005

X‐ray K‐absorption edges of cobalt in some metallic soaps (myristate, palmitate, stearate and oleate) and their solutions in benzene have been recorded. The latter are liquid crystals. The bond length between the metal and the ligand was found to be greater in solutions than in the solids.
Quantitative light element analysis using an energy‐dispersive detector: 3—practical assessment of accuracy and sensitivity
Authors: Bloomfield D. J. , Love G. , Scott V. D.
Published: May 2005

A comparison has been made between light element (5 < Z < 11) analyses performed using energy‐dispersive and wavelength‐dispersive spectrometry. It is shown that, provided appropriate spectrum processing methods are adopted, the two sets of data agree to within 2–3%. Since there is every reason to believe the wavelength‐dispersive measurements are accurate, this demonstrates the feasibility of carrying out quantitative light element analysis by the energy‐dispersive technique. The minimum concentrations of carbon, nitrogen and oxygen which can be detected in selected matrices have been established and it is shown that sensitivities of better than 0.5 wt% are achievable if the electron probe voltage is carefully chosen.
Rapid, high‐quality major and trace element analysis of powdered rock by X‐ray fluorescence spectrometry
Authors: Rose William I. , Bornhorst Theodore J. , Sivonen Seppo J.
Published: May 2005

Rapid and high‐quality major and trace element data can be obtained by automated x‐ray fluorescence (XRF) analysis of pressed rock powder pellets. The sample preparation procedure is simple, quick and can be done well with minimal supervision. Analysis of the rock pellet for 22 elements requires about 1 h of machine time. The system is calibrated by use of multiple international rock standards and employs a ratio standard for all measurements. Most calibrations are simple linear fits between intensity and concentration. The precision of the major element results are generally better than ±1% of the amount determined, whereas the trace element precisions are generally less than 5%, except when the value determined is close to the detection limit. Accuracies are comparable to those of other published XRF rock analysis procedures.