bluuebunny/crossref_metadata_2025_split huggingface dataset:
SEM studies on silica from plant materials
Authors: Prasanna P. , Patel M. 
Published: May 2005

AbstractThe Silica structural framework in plant materials can be separated from the organic part by acid leaching and can be examined by SEM. Scanning electron micrographs characterizing the bonding and distribution patterns of silica in rice husk, rice straw and sugarcane leaves are presented. The differences in the surface morphology of the three plant products are discussed.
Analysis of fused samples using influence coefficients obtained from synthetic standards
Authors: Ward J. , Valdes J. 
Published: May 2005

AbstractA mathematical approach is presented which permits a simple calculation of influence coefficients using intensities measured in a set of suitably chosen synthetic standards. A set of n standards suffices for obtaining all the coefficients necessary for the analysis of a matrix with n elements. An evaluation of such coefficients has been carried out for silicate‐type samples. The results show that if theory is guided by some practical considerations, highly effective coefficients can be obtained. The method can be applied to several types of substances that require fusion prior to analysis.
Effect of some important sample parameters on the X‐ray fluorescence determination of impurities in pure materials: Determination of Ca, Y, Gd and Th in uranium
Authors: Agrawal R. M. , Kapoor S. K. 
Published: May 2005

AbstractCalibration standards obtained by dry mixing of the components in appropriate proportions may be compositionally accurate but they can be a major source of error in the X‐ray fluorescence analytical results owing to the mismatch in the degree of their homogeneity with that of the sample. An in‐depth study has been made on the above aspect taking U3O8 as a matrix and Ca, Y, Gd and Th in the low concentration range (0—1500 ppm) as representative impurities. This study clearly illustrates the incompatibility of the truly homogeneous standards with the standards obtained by dry mixing and grinding. This incompatibility is dependent on the analytical line wavelength, being large for soft X‐ray lines and small for harder X‐rays.The effect of binding material which is often required for briquetting the sample into a pellet form and is necessarily to be mixed with the sample by dry mixing is discussed.
Comparison of experimental relative efficiencies for different Si(Li) detectors in the energy range, 4.5–17.5 keV
Authors: Yap C. T. , Kump P. , Tang S. M. , Bilal M. G. 
Published: May 2005

AbstractThe relative efficiencies of four Si(Li) detectors from three different manufacturers were studied. The results show that such efficiencies depend not only on the shape and size of the detector's sensitive volume but also on the collimator assembly and centralized or off‐centre mounting of the crystal within the cryostat. It is therefore necessary to calibrate the XRF spectrometer in the same geometric configuration which will be used for the intended application in elemental analysis; calculated model‐dependent efficiencies can be very different from experimental efficiencies.
Application of the coherent‐to‐incoherent intensity ratio to the measurement of mineral matter in coals
Authors: Dale L. S. , Matulis C. E. 
Published: May 2005

AbstractThe relationship between the scattering of X‐rays from coal samples and their chemical composition has been investigated using a theoretical model based on the concept of the isolated atom. Model calculations were used to assess the coherent‐to‐incoherent intensity ratio as a means of determining the mineral matter content of coals, and the scope of this application was studied in detail. The procedure was verified theoretically by using the model on a set of well characterized coals. Using a relatively simple calibration procedure the experimentally determined mineral matter agreed with the radiofrequency ash values to within 7.6% rms.
Routine method of X‐ray spectrometric analysis without standards involving only initial instrumental calibration 2—Practical calculation equations for iteration in an iron‐based alloy system constituted by ten elements and their experimental determination
Authors: Wang Yongzhong , Chen Zhimin 
Published: May 2005

AbstractBased on the theoretical equations for calculations in X‐ray fluorescence spectrometric analysis without standards in Part 1, a set of equations for practical iteration applied to an iron‐based alloy constituted by ten elements are presented. Some of factors that affect the accuracy of the results are explained and determined. Forty steel alloy specimens were analysed without standards. The results show that the deviations from the results of wet chemical analyses are small, and the geometric configuration of specimen is generally not required.
Elemental analysis of coal ash using energy‐dispersive X‐ray fluorescence
Authors: Rao N. Venkateswara , Raghavaiah C. V. , Satyanarayana G. , Sastry D. L. 
Published: May 2005

AbstractAn energy‐dispersive X‐ray fluorescence spectrometer was used to analyse about 100 samples of coal ash. The elemental concentrations were determined using the standardless method and fundamental parameter approach. It was found that the Fe concentration was as high as nearly 30% in some samples. The results suggest that S, Ca, Ti and Fe are the major components that require corrections to be applied owing to X‐ray fluorescence in the back‐scattering techniques used for the determination of the ash fraction in coal.
An approach to the solution of matrix problems in the XRF analysis of lead–zinc ore by the use of an internal standard and mathematical corrections
Authors: Mahapatra N. S. 
Published: May 2005

AbstractFor the determination of the lead, zinc and iron contents of bore‐hole samples from the Rampura‐Agucha lead‐zinc deposit, X‐ray fluorescence spectrometry has been used. The concentration range of the metals, present in the ore body as galena, sphalerite, pyrite and pyrrohotite, is very wide: for Zn 0—30%, for Pb 0—10% and for Fe 1—16%. An internal standard method and a concentration based correction equation have been used to solve the effect of matrix variations, which is the major problem in the development of the programme.Copper added as copper sulphate, which also acts as a good binder, was used as an internal standard for zinc. For Pb Lα1 an adjacent Rayleigh diffraction line, Au Lβ1, was used as an internal standard and partially compensates for the matrix effect. The residual correction is made by the use of a mathematical model. For iron, only a mathematical correction is made. There is good agreement between the XRF and wet chemical analysis results for zinc and lead. For iron, the absolute differences are larger, but the correlation coefficient is good for average analysis of a series.
Importance of sample grinding time in X‐ray emission spectrometry
Authors: Novosel‐Radović V. J. , Maljković D. A. 
Published: May 2005

AbstractThe effect of the sample grinding time on X‐ray spectrometric results was examined on real samples (limonite iron ore, sinter mixture and blast furnace slag). Comparative results were obtained for X‐ray diffraction analysis and scanning electron microscopic analysis. The optimal grinding time depended on the type of analyte and on the phase composition of the sample.
X‐ray fluorescence determination of trace element concentrations of zinc and arsenic and their relation to ceramic attribution
Authors: Yap C. T. 
Published: May 2005

AbstractAbsolute values of concentrations of zinc and arsenic for ceramics were obtained using an energy‐dispersive X‐ray fluorescence technique. One hundred and fifteen pieces of Chinese Jingdezhen porcelains from late Ming to 1983, including a few non‐Jingdezhen pieces, were studied. For all pieces of Chinese porcelains made in Jingdezhen from late Ming to the Republic period, the results show that zinc was present in very small quantities (<70 ppm) whereas arsenic was completely absent. However, after World War II, many pieces were found to contain relatively large concentrations of both zinc and/or arsenic. This could then be a simple, non‐destructive method of detecting modern fakes.
Modification of Philibert–Tixier ZAF correction for geological samples
Authors: Fialin Michel 
Published: May 2005

AbstractTwo steps are usually used in electron microprobe correction: (1) development of a theoretical mode based on physical phenomena within pure or binary targets; and (2) simplification of certain complexities due to multi‐element samples by using average coefficients in the theoretical equations. It is proposed to use a more detailed method of estimating the general correction coefficients concerning A/Z relationships in the absorption and ionization terms of the theoretical formulation. In the absorption formulation the factor h is taken as (1.2 ∑ CiAi/Zi2)/ (1 + Ka). The value of a is given as ‐1. In the ionization relationship M = (∑ CiZi/Ai)/(1 + Kb) with b = E0/100, where E0 is the accelerating voltage in kV. K, deduced from experimental results, is given as K = ∑ Ci(Zi ‐ Z¯), where Z¯ is the average atomic number of the target.These values are derived empirically through direct measurements on samples whose correction properties induce normally strong analytical errors: oxides with 11 ⩽ Z ⩽ 14 analysed within a heavy matrix.
X‐ray K absorption spectroscopic study of some Schiff‐base polymers of cobalt
Authors: Mujumdar P. V. , Deshmukh Prabodhachandra C. , Sapre V. B. , Bhave N. S. 
Published: May 2005

AbstractThe results of a study of the x‐ray K absorption spectrum of cobalt in the elemental form and in some of its Schiff‐base coordination polymers are presented. The K absorption discontinuity of cobalt was recorded together with the x‐ray absorption near‐edge structure (XANES) and extended x‐ray absorption fine structure (EXAFS) associated with it by employing a 0.4 m Cauchois‐type bent‐crystal spectrograph. The (100) planes of a muscovite mica analyser crystal were used for reflection of x‐radiation, the source of which was the tungsten target of a Chirana conventional x‐ray tube. Measurements were made of the chemical shift, edge width, XANES and EXAFS associated with the discontinuity. Levy's theory and the graphical method based on the theory of Stern and coworkers were employed to determine the average radius of the first coordination sphere surrounding the cobalt atom in all the systems studied. The results are discussed in terms of the bond length, bond ionicity, coordination geometry and some other parameters related to the local environment of the absorbing cobalt atom.
Quantitative trace element determination in thin samples by total reflection x‐ray fluorescence using the scattered radiation method
Authors: Yap C. T. , Ayala R. E. , Wobrauschek P. 
Published: May 2005

AbstractIt is shown that samples exposed under total reflection conditions obey the relationship Ii/Iinc = KCi, where Ii is the x‐ray fluorescence intensity due to element i of concentration Ci, Iinc is the intensity of the scattered incoherent radiation and K is a constant. An experiment on the determination of sulphur in diesel fuel confirmed this derivation. This relationship affords a simple and fast method for quantitative trace element determination, requiring virtually no sample preparation and extremely small amounts (<Iμl). Other advantages include its insensitivity to instrumental variations and changes in excitation conditions or in sample characteristics such as particle size and sample amount.
Shape and extended fine structure of the x‐ray K‐absorption discontinuity in some cobalt mixed‐ligand complexes
Authors: Khadikar Padmakar V. 
Published: May 2005

AbstractCorrelation of the variation in the distance between cobalt ions and its nearest neighbours with the variation in the covalency of the metal—ligand bond was estimated from the shape and the extended fine structure of cobalt K‐absorption discontinuity in some cobalt mixed‐ligand complexes.
X‐ray fluorescence analysis of samples with elemental sulphur. Effect of sulphur sublimation
Authors: Chinchón J. S. , López‐Soler A. , Travería A. , Vaquer R. 
Published: May 2005

AbstractThe precautions to be taken during x‐ray fluorescence (XRF) analysis of samples containing elemental sulphur were investigated. Elemental sulphur under vacuum (vacuum required for S Kα analysis) undergoes sublimation. As a result, the sulphur intensity signal diminishes in direct relation to the time during which the sample has been under vacuum. The work power accelerates the sublimation of sulphur. A method for obtaining real analytical values is proposed. The risk to the XRF spectrometer constituted due to sublimed sulphur are pointed out.
Scanning electron microscopic studies of pore formation in mica schist insulating brick
Authors: Patel M. 
Published: May 2005

AbstractSEM micrographs showing porous structures and bonding of pores through broken mica flakes are presented. Pores of varying dimensions (10–400 μm) are formed. Interlayer spaces in mica are shown to be the preferential direction for heat and subsequently crack propagation during heat treatment for producing cellular insulating bricks at 900°C. The cracks end up with the formation of large pores in the presence of foaming agent and sodium silicate.
Fitness of metallic disc samples for the determination of cerium in cast iron by X‐ray emission spectrometry
Authors: Sofilić T. , Maljković Da. 
Published: May 2005

AbstractSamples in the form of metallic disc are frequently used in the analysis of cast iron by x‐ray emission spectrometry and give good results for common analyses (determination of carbon, sulphur, phosphorus, silicon, manganese, copper, etc.) because of the uniform distribution of the analyte in the sample. However, the results of the analysis of metallic disc samples of cast iron to which cerium had been added were poor, which could be attributed to a non‐uniform distribution of compounds which cerium formed with sulphur and oxygen. A more detailed investigation of cerium distribution in relation to its content in the sample gave evidence of the presumed non‐uniform distribution. Scanning electron microscopy confirmed the presence of unequally distributed aggregates of different size containing cerium, sulphur and oxygen. On the basis of an examination and comparison of published pretreatment procedures, a modified procedure including cerium precipitation with oxalate without transformation into the oxide form is proposed. Using this method, greater reliability of the results was obtained than in the analysis of cast iron samples without pretreatment, i.e. in the disc form.
A method of correcting dead time and pulse pile‐up errors in energy‐dispersive X‐ray analysis
Authors: Gui‐Nian Diao , Turner K. E. 
Published: May 2005

AbstractThe Barnhart pulse pile‐up and dead time correction method is used by a number of manufacturers of energy‐dispersive x‐ray analysers. This method may provide inadequate correction at moderately high count rates and/or in the presence of low‐energy x‐ray peaks. A correction scheme is proposed to overcome these difficulties and its effectiveness is illustrated by the analysis of several homogeneous mineral samples of well established composition.
Angular dependence of X‐ray fluorescence intensities
Authors: De Boer D. K. G. 
Published: May 2005

AbstractThe x‐ray fluorescence intensity of a sample contains the product of two angular‐dependent factors: the first describes the angular dependence of the absorption of both incident and emitted radiation and the second is a geometrical factor accounting for the angular variation of irradiated and detected surface area. Theory for the angular dependence of x‐ray intensities is presented. Good agreement is found with experimental data, measured with a novel focusing spectrometer using a small silicon detector. Measurement of the angular dependence of intensities is especially promising for the analysis of multi‐layer samples.
Matrix corrections for quantitative determination of trace elements in biological samples using energy‐dispersive X‐ray fluorescence spectrometry
Authors: Kumar Sudhir , Singh Surinder , Mehta D. , Garg M. L. , Mangal P. C. , Trehan P. N. 
Published: May 2005

AbstractAn experimental method for the evaluation of the matrix absorption correction (8) for the determination of trace elements in thick biological samples using EDXRF is discussed. The validity of the method was checked in two ways, first by comparing the experimental values with theoretical estimated values for samples of known matrix and second by analysing NBS biological standards in the form of thick pellets. It was found that a sample thickness of 40‐70 mg cm−2 is, in general, optimum for the analysis of biological samples in pellet form with an excitation energy of 22.6 keV.
X‐ray photoelectron spectroscopic studies on silicon carbide from rice husk
Authors: Patel M. 
Published: May 2005

AbstractThe surface structure of silicon carbide whiskers, produced from rice husk at 1500–1800°C, was examined by x‐ray photoelectron spectroscopy. An ESCA survey scan of the surface showed Si, C, O and F to be present; Si in the form of SiCx and SiOx and C in the form of SiCx and CHx. On sputtering the sample, the SiOx and CHx species were reduced and the SiCx level increased. The photoelectron spectra are presented.
Wear and tear studies of oil‐lubricated machines using energy‐dispersive X‐ray fluorescence spectrometry
Authors: Bhat C. K. , Kaul D. , Lodha G. S. , Koul R. , Sawhney K. J. S. 
Published: May 2005

AbstractThe wear of oil‐lubricated machines was monitored by establishing a correlation between the wear rate of the machine and the concentration of heavy metal contaminants in the lubricating oils used. The concentrations of heavy metal contaminants in the oil were determined using energy‐dispersive X‐ray fluorescence spectrometry. To obtain a representative sample, the procedure for sample collection and preparation was standardized. Samples were collected from a 30 KVA diesel generator set at BARC‐NRL at regular intervals. The concentrations of Fe, Cr and Ni were found to increase with increase in the number of hours in service.
Lα/Lβ; and Lα/Lγ x‐ray intensity ratios for elements in the range Z = 55–80
Authors: Raghavaiah C. V. , Rao N. Venkateswara , Reddy S. Bhuloka , Satyanarayana G. , Murty G. Sree Krishna , Rao M. V. S. Chandrasekhar , Sastry D. L. 
Published: May 2005

AbstractA systematic study of Lα/Lβ and Lα/Lγ x‐ray intensity ratios was undertaken by measuring the characteristic x‐ray intensities in 23 elements over the range Z = 55‐80, using a 30 mCi 238Pu source of excitation and a high‐resolution Si(Li) detector system coupled to a computer‐controlled multi‐channel analyser. The theoretical predictions due to Scofield were computed for the present energy (weighted average) of 15.28 keV excitation and compared with the experimental values. The experimental values of Lα/Lβ and Lα/Lγ versus Z were fitted to a fourth‐degree polynomial, and most probable values of Lα/Lβ and Lα/Lγ at each Z were also determined using this fit.
Study of K‐absorption edge of selenium in the glassy semiconducting Se100−xInx system
Authors: Kumar Arvind , Husain M. , Swarup S. , Nigam A. N. , Kumar A. 
Published: May 2005

AbstractThe shift of the K‐absorption edge (δEk) was measured in Se100‐xInx binary system where 0 ≤x ≤ 30. The K‐edge of Se progressively shifted toward the lower energy side as the In concentration increased from 0 to 15 at.‐%. However, at higher concentrations, the relative shift started to decrease. The results are in accordance with Pauling's concept of electronegativity and indicate that the nature of the bonds is iono‐covalent in these glasses, as found in many crystalline solids. The composition dependence of the edge shift is also discussed in terms of the structure of Se.
Determination of sample thickness via scattered radiation in x‐ray fluorescence spectrometry with filtered continuum excitation
Authors: Araújo M. Fátima , Van Espen P. , Van Grieken R. 
Published: May 2005

AbstractA semi‐empirical approach is described for determining the mass per unit area of a sample being analysed. The method can be used to estimate the concentration of minor and trace elements in matrices containing a substantial amount of light elements. The procedure utilizes the coherently and incoherently scattered radiation induced in the sample by the filtered continuum radiation of a rhodium x‐ray tube. The relationship between the intensity of the scattered radiation per unit mass and the average atomic number of the sample is established via calibration graphs, which can be applied for different x‐ray tube voltages and for different primary beam filters. The overall procedure was validated by the analysis of several geological standards, deposited as thin slurries of unknown thickness either on Mylar foil or on Nuclepore filters.
Characterization of II–VI semiconductor materials using surface analytical techniques
Authors: Kibel Martyn H. 
Published: May 2005

AbstractThe production, properties and structure of II–VI semiconductor materials are topics of increasingly intense research activity. This paper discusses the use of the surface analytical techniques x‐ray photoelectron spectroscopy, Auger electron spectroscopy and energy‐dispersive x‐ray spectroscopy to study and characterize these materials, and hence assist in understanding the growth process.
Characterization of II–VI semiconductor compounds grown by metallo‐organic chemical vapour deposition
Authors: Christiansz G. I. , Georgiou S. , Kwietniak M. S. , Pain G. N. , Usher B. , Warminski T. , Glanvill S. R. , Rossouw C. J. , Stevenson A. W. , Wilkins S. W. , Wielunski L. 
Published: May 2005

AbstractCdTe and HgCdTe epitaxial layers were grown on 50 mm diameter (100) GaAs wafers in a Quantax 226 metallo‐organic chemical vapour deposition system. Dimethylcadmium, diethyl telluride and elemental mercury were used as starting materials in the thermal growth process which takes place in a flow of hydrogen at 250–350°C. The layers were characterized by (1) an interference contrast microscope for surface morphology; (2) FTIR spectros‐copy for compositional and thickness uniformity; (3) x‐ray topography and double crystal diffractometry for the non‐destructive evaluation of the crystalline quality and microstructure; (4) energy‐dispersive x‐ray analysis (WDX/EDX) for compositional studies; (5) transmission electron microscopy for interface observations and analysis; and (6) Rutherford backscattering and channelling analysis for surface stoichiometry and crystal quality determinations.
Some considerations on the use of Lα series of transition metals in electron probe microanalysis: The example of zinc minerals
Authors: Fialin Michel 
Published: May 2005

AbstractIt is shown, using measurements on certain zinc minerals, that the Lα emission of transition metals can be affected as follows. First, the band shape is often changed in the range of the satellite emission which implies, for data acquisition, the use of the total band area instead of the measurements at the peak maximum. Second, the physical process of self‐absorption of Lα photons (here, the absorption of Zn Lα in Zn) depends on the nature of the specimen (metal, semiconductor, insulator), In EPMA, the corresponding theoretical parameter, which is the mass self‐absorption coefficient, may be then changed between an unknown and standard, despite the assumption of constancy in matrix‐effect correction models. Both phenomena are correlated because of their strong dependence on the electronic structure of the M5 level, which can be modified in poor conducting materials by the presence of holes. The choice of suitable standards is then crucial in order to perform accurate k‐ratio measurements.