Strategies for Preferred Orientation Corrections in X-Ray Powder Diffraction using Line Intensity Ratios

1991 ◽  
pp. 409-415 ◽  
Author(s):  
B. H. O’Connor ◽  
D. Y. Li ◽  
H. Sitepu
Keyword(s):  
Powder Diffraction ◽  
Line Intensity ◽  
Preferred Orientation ◽  
X Ray ◽  
Intensity Ratios

Use of an air brush to spray dry samples for X-ray powder diffraction

Clay Minerals ◽  
1999 ◽  
Vol 34 (1) ◽  
pp. 127-135 ◽  
Author(s):  
S. Hillier
Keyword(s):  
Bulk Density ◽  
Powder Diffraction ◽  
Marked Improvement ◽  
Smooth Surface ◽  
Preferred Orientation ◽  
Spray Drier ◽  
Spray Dry ◽  
X Ray ◽  
Spray Gun ◽  
Spray Dried

AbstractThe construction and operation of a spray drier is described where the spray is produced using an air brush, essentially a miniature spray gun. The spray-dried products consist of spheres 50–60 µm in diameter and typical product recoveries are 80%, a marked improvement over simple two-nozzle systems. The spray-dried samples are easy to load into XRD powder holders and present a smooth surface and relatively constant bulk density to the X-ray beam. Problems of preferred orientation are effectively eliminated and the resulting X-ray powder patterns are completely reproducible by different operators.

X-ray Powder Diffraction QPA by Rietveid Pattern- Fitting - Scope and Limitations

1989 ◽  
Vol 33 ◽  
pp. 269-275 ◽  
Author(s):  
B.H. O'Cannar ◽  
Li Deyu ◽  
B. Jordan ◽  
M. D. Raven ◽  
P. G. Fazey
Keyword(s):  
Powder Diffraction ◽  
Preferred Orientation ◽  
Analytical Science ◽  
Materials Analysis ◽  
X Ray ◽  
University Of Technology ◽  
Science Group

AbstractThe X-ray Analytical Science Group at Curtin university of Technology has been developing and evaluating Rietveld pattern-fitting for materials analysis since 1985. The results are reviewed with particular reference to preferred orientation, crystallinity and phase abundance.

Comparative evaluation of the March and generalized spherical harmonic preferred orientation models using X-ray diffraction data for molybdite and calcite powders

2005 ◽  
Vol 38 (1) ◽  
pp. 158-167 ◽  
Author(s):  
Husin Sitepu ◽  
Brian H. O'Connor ◽  
Deyu Li
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Spherical Harmonic ◽  
Comparative Evaluation ◽  
Preferred Orientation ◽  
Composition Analysis ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray

Preferred crystallographic orientation,i.e.texture in crystalline materials powder diffraction data, can cause serious systematic errors in phase composition analysis and also in crystal structure determination. The March model [Dollase (1986).J. Appl. Cryst.19, 267–272] has been used widely in Rietveld refinement for correcting powder diffraction intensities with respect to the effects of preferred orientation. In the present study, a comparative evaluation of the March model and the generalized spherical harmonic [Von Dreele (1997).J. Appl. Cryst.30, 517–525] description for preferred orientation was performed with X-ray powder diffraction data for molybdite (MoO3) and calcite (CaCO3) powders uniaxially pressed at five different pressures. Additional molybdite and calcite powders, to which 50% by weight silica gel had been added, were prepared to extend the range of preferred orientations considered. The patterns were analyzed initially assuming random orientation of the crystallites and subsequently the March model was used to correct the preferred orientation. The refinement results were compared with parallel refinements conducted with the generalized spherical harmonic [Sitepu (2002).J. Appl. Cryst.35,274–277]. The results obtained show that the generalized spherical harmonic description generally provided superior figures-of-merit compared with the March model results.

scholarly journals X-ray Lines From Mg VIII and Si X Ions and Their Diagnostic Use

1990 ◽  
Vol 115 ◽  
pp. 40-43
Author(s):  
Bhola N. Dwivedi
Keyword(s):  
Electron Density ◽  
Line Intensity ◽  
Coronal Holes ◽  
Emission Lines ◽  
X Ray ◽  
Quiet Sun ◽  
Diagnostic Use ◽  
Line Intensity Ratio ◽  
Theoretical Line ◽  
Intensity Ratios

AbstractThe solar X-ray emission lines from Mg VIII and Si X ions have been studied. The variation of theoretical line intensity ratio I(λ 75.03)/I(λ 74.86) from Mg VIII and I(λ 50.69)/I(λ 50.52) from Si X as a function of electron density is found to be good density monitors of the emitting regions of solar plasma. The computed values of line intensity from these ions based on Kopp and Orrall model have been used to derive electron density of the quiet Sun and coronal holes. The electron densities of 109 cm-3 and 4.6 × 108 cm-3 are estimated at the electron temperatures of 8 x 105 K and 1.6 x 106 K for the quiet Sun whereas the respective values of 5.4 x 108 cm-3 and 1.7 x 108 cm-3 are obtained for the coronal holes. The line intensity ratios studied here are independent of temperature variation and are therefore excellent candidates for electron density diagnostics. However, observational data with improved spectral resolution is needed for using X-ray line pairs studied for their diagnostic use.

An improved method for quantitative analysis of sedimentary minerals by X-ray diffraction

1996 ◽  
Vol 11 (3) ◽  
pp. 235-239 ◽  
Author(s):  
Wang Chao ◽  
Pan Chunde ◽  
Wang Daqing ◽  
Song Aixia ◽  
Nie Jihong ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Preferred Orientation ◽  
Improved Method ◽  
X Ray Diffraction ◽  
Absolute Deviation ◽  
X Ray ◽  
Sedimentary Environments ◽  
Loading Method ◽  
Intensity Ratios ◽  
Comparison Of The Results

An improved backloading method to determine the reference intensity ratios of sedimentary minerals is presented. More than 50 reference intensity ratios of more than ten types of minerals formed in typical sedimentary environments were measured. Quantitative tests were performed on those minerals. Comparison of the results show that this method minimizes preferred orientation and improves quantitative precision (absolute deviation is less than 3%) so that it is an acceptable specimen loading method.

X-ray powder diffraction data for acetamidinium formate C3H8N2O2, elimination of preferred orientation effect

2017 ◽  
Vol 32 (4) ◽  
pp. 268-270
Author(s):  
J. Maixner ◽  
P. Kačer
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell Volume ◽  
Preferred Orientation ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters

X-ray powder diffraction data, unit-cell parameters, and space group for acetamidinium formate, C3H8N2O2, are reported [a = 6.4564(5) Å, c = 13.021 (3) Å, unit-cell volume V = 542.8(3) Å3, M.p. = 215(1)°C, ρc = 1.274 g.cm−3, ρm = 1.269 g.cm−3, Z = 4, and space group P43212]. The front-loaded technique got sample with strong preferred orientation because of plate-like shape of crystallites, so the capillary packing was used for final powder data collection. All measured lines were indexed and are consistent with the P43212 space group. No detectable impurities were observed.

Use of X-Ray Powder Diffraction Rietveld Pattern-Fitting for Characterising Preferred Orientation in Gibbsites

1990 ◽  
Vol 5 (2) ◽  
pp. 79-85 ◽  
Author(s):  
Li Deyu ◽  
Brian H. O'Connor ◽  
Gerald I.D. Roach ◽  
John B. Cornell
Keyword(s):  
Powder Diffraction ◽  
Correction Method ◽  
Preferred Orientation ◽  
Empirical Measure ◽  
General Application ◽  
X Ray ◽  
Line Intensities ◽  
Orientation Effects ◽  
Xrpd Pattern

AbstractA study has been conducted with gibbsite specimens, on the use of Rietveld X-ray powder diffraction (XRPD) pattern fitting for quantitating preferred orientation in powders. This study has shown that an earlier formula gives results which correlate closely with an empirical measure of morphology proposed recently for gibbsite powders, viz., the ratio of the XRPD intensities for the (002) line and the (110, 200) doublet lines. A method is proposed on the basis of this correlation for the correction for preferred orientation of line intensities in gibbsite powder patterns. The correction method appears to have excellent potential for XRPD quantification of gibbsite levels in mixtures, and could have general application for coping with preferred orientation effects in the quantitation of other phases.

Strategies for Preferred Orientation Corrections in Xray Powder Diffraction Using Line Intensity Ratios

1990 ◽  
Vol 34 ◽  
pp. 409-415
Author(s):  
B.H. O'Connor ◽  
D.Y. Li ◽  
H. Sitepu
Keyword(s):  
Line Intensity ◽  
Rietveld Analysis ◽  
Preferred Orientation ◽  
Quantitative Phase Analysis ◽  
Orientation Model ◽  
Line Intensity Ratio ◽  
Ratio Approach ◽  
Intensity Ratios ◽  
Related Line ◽  
Orientation Bias

AbstractLi et al (1990) reported experiments with gibbsite powder specimens on the use of Rietveld pattern-fitting, involving the March preferred orientation model, to characterise preferred orientation according to the March r parameter. It was shown that intensity corrections may be applied with the March r parameter derived from Rietveld analysis or with the related line intensity ratio MR which is sensitive to preferred orientation. The present paper reports an analytic expression involving r and MR which has proved highly reliable for the correction of preferred orientation bias in quantitative phase analysis of gibbsite. Similar expressions may be readily derived for other materials for which the March model is appropriate. Therefore the line ratio approach has considerable potential for rapid correction of intensities for preferred orientation.

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