AN ANALYSIS OF THE EFFECTS OF SAMPLE PROCESSING ON X-RAY POWDER DIFFRACTION PEAKS AND THE IMPLICATIONS FOR STUDIES OF SHOCK METAMORPHOSED CARBONATES

2019 ◽  
Author(s):  
Emily N. Simpson ◽  
◽  
Keith A. Milam
Keyword(s):  
Powder Diffraction ◽  
Sample Processing ◽  
X Ray ◽  
Diffraction Peaks

Rietveld Structure Refinement of Metastable Lithium Disilicate Using Synchrotron X-Ray Powder Diffraction Data From the Daresbury SRS 8.3 Diffractometer

1990 ◽  
Vol 5 (3) ◽  
pp. 137-143 ◽  
Author(s):  
R.I. Smith ◽  
A.R. West ◽  
I. Abrahams ◽  
P.G. Bruce
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Powder Diffraction Data ◽  
X Ray ◽  
New Instrument ◽  
Diffraction Peaks

AbstractThe crystal structure of metastable Li2Si2O5, Fw = 150.05, has been refined by the Rietveld method using high resolution X-ray powder diffraction data recorded at the Daresbury Synchrotron Radiation Source on the new 8.3 diffractometer. Li2Si2O5, in keeping with many compounds of interest to the materials scientist, exhibits relatively broad diffraction peaks. It is important to establish the quality of crystal structure data that may be obtained from such materials on this new instrument. Various functions were used to model the peak shape from this instrument; a split-Pearson VII function appeared to be marginally superior to Pearson VII or Pseudo-Voigt functions. Refinement was carried out using the split-Pearson VII in the space group Pbcn (60) and terminated with a = 5.6871(6), b = 4.7846(5), c = 14.645(1) Å, V = 398.50 Å3, Z=4, Dc= 2.502 gcm−3, Rwp = 17.06, Rex = 14.48 and Χ2 = 1.39. The refined parameters are compared with those obtained from a previous single crystal X-ray determination.

The Use of Fourier Self-Deconvolution to Resolve Overlapping X-Ray Powder Diffraction Peaks

1989 ◽  
Vol 4 (3) ◽  
pp. 144-151
Author(s):  
Ernest E. Armstrong ◽  
David G. Cameron
Keyword(s):  
Powder Diffraction ◽  
Curve Fitting ◽  
Weight Percent ◽  
Quantitative Information ◽  
X Ray ◽  
Comparison Of Results ◽  
Overlapping Peaks ◽  
Diffraction Peaks

AbstractFourier self-deconvolution has been successfully applied as a means of obtaining semi-quantitative information by resolving the overlapping peaks in X-ray powder diffractograms collected from mixtures of kaolinite and ripidolite. A series of diffractograms were collected from known mixtures of the two minerals. The diffractograms were then processed using Fourier self-deconvolution over a selected range between 23 and 27° 2θ (encompassing the overlapping peaks of kaolinite (002) and ripidolite (004) at 24.85 and 25.13° 2θ, respectively). Once deconvoluted, areas under individual peaks of kaolinite and ripidolite were calculated using curve fitting. The calculated percentage of kaolinite in the mixtures was then plotted versus the true weight percent of kaolinite. The same procedure was conducted on the original diffractograms using only curve fitting without first deconvoluting. A comparison of results shows that, provided the number of peaks are known, both methods give nearly equal results. However, Fourier self-deconvolution, by increasing the resolution, greatly improves the ability to detect overlapping peaks.

Investigation of diffraction line broadening due to compositional fluctuations in L-alanine-doped triglycine sulfate

2003 ◽  
Vol 59 (5) ◽  
pp. 647-652 ◽  
Author(s):  
Rajul Ranjan Choudhury ◽  
R. Chitra ◽  
M. Ramanadham
Keyword(s):  
Powder Diffraction ◽  
Triglycine Sulfate ◽  
Diffraction Line ◽  
Line Broadening ◽  
X Ray ◽  
Alanine Substitution ◽  
Anisotropic Strain ◽  
Diffraction Peaks ◽  
Compositional Disorder ◽  
Hall Method

Broadening of X-ray powder diffraction peaks as a result of compositional disorder in L-alanine-doped triglycine sulfate crystals is investigated using the Williamson–Hall method. The analysis indicates that L-alanine substitution in triglycine sulfate crystals leads to anisotropic strain in the crystal.

scholarly journals Determination of the activation energies of phase transition for calcium orthophosphates based on powder X-ray diffraction data

2021 ◽  
Author(s):  
Kateryna Vasylenko ◽  
Yuriy Sakhno ◽  
Deb Jaisi ◽  
Mykola Nikolenko
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Calcium Phosphate ◽  
Powder Diffraction ◽  
Early Stage ◽  
Degree Of Crystallinity ◽  
Calcium Orthophosphate ◽  
X Ray ◽  
Calcium Orthophosphates ◽  
Diffraction Peaks

Abstract Kinetic studies of the transformation of calcium orthophosphates metastable precipitates were performed under different synthesis conditions. Phase composition and degree of crystallinity were investigated by X-ray powder diffraction analysis. In acidic solution, precipitates of CaHPO4⋅2H2O (DCPD) and CaHPO4 (DCPA) are formed at the early stage of precipitation, with the degree of crystallinity at the range of 17–35%. Specifically, DCPD precipitates at 30°C and anhydrous DCPA at 50°C. In alkaline solution (pH 8–10), only amorphous forms of calcium orthophosphate is precipitated, which is explained by the high degree of supersaturation (i.e., the high rate of precipitation compared to that in acidic media). The diffraction peaks of DCPD and DCPA are found to be 0.3–0.45 degrees lower relative to their reference data, which is caused by decrease of lattice strain during early stage of crystallization. Furthermore, the initial molar ratio of Ca/P in reagent mixture was found to play subordinary role in determining the composition of final calcium phosphate precipitates. The effect of pH on the composition of precipitates is illustrated by the solubility isotherms of pure calcium orthophosphates. Given that the intensities of diffraction peaks are proportional to planar density of the material in the given plane, we propose, for the first time, to determine activation energy of phase transformation of calcium orthophosphate from X-ray powder diffraction patterns. Based on this relationship developed, the activation energy for the recrystallization DCPD and DCPA are 10.2 and 13.1 kJ/mol, respectively and for the phase transition of DCPD to DCPA – 36.7 kJ/mol. Further recrystallization to most thermodynamically stable Ca10(PO4)6(OН)2 hydroxyapatite (HA) occurs at the activation energy of 5.2 kJ/mol. These findings are critical on phase transition and transformation of calcium phosphate minerals.

X-ray powder diffraction data for the N-acylamino acids: ortho, meta, and para-methyl hippuric acids

2016 ◽  
Vol 31 (3) ◽  
pp. 242-247
Author(s):  
Gerzon E. Delgado ◽  
Marilia Guillén ◽  
Jeans W. Ramírez ◽  
Asiloé J. Mora ◽  
Jines E. Contreras ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Space Groups ◽  
Cell Parameters ◽  
Methylhippuric Acid ◽  
Diffraction Peaks

N-acylamino acid isomers: ortho, meta, and para-methylhippuric acids, are specific xylene metabolites. Here, we report X-ray powder diffraction data, unit-cell parameters, and space groups for the three isomer (C10H11NO3), [ortho-methylhippuric acid 2 mHA, monoclinic P21/n cell, a = 8.522(1), b = 10.443(1), c = 10.734(1) Å, β = 92.43(1)°, V = 954.5(1) Å3; meta-methylhippuric acid 3 mHA, monoclinic C2/c cell a = 20.0951(2), b = 10.485(1), c = 10.074(2) Å, β = 119.08(1)°, V = 1933.9(1) Å3; para-methylhippuric acid 4 mHA, orthorhombic P212121 cell, a = 5.1794(7), b = 8.279(1), c = 22.276(2) Å, V = 955.2(2) Å3], space group. In each case, all measured diffraction peaks were indexed and are consistent with the corresponding space group.

Synthesis and X-Ray Powder Diffraction Analysis of a New Metallic (but not Superconducting) Copper Oxide: La1.67Sr0.33Cu2O5

1988 ◽  
Vol 3 (2) ◽  
pp. 81-83 ◽  
Author(s):  
T. C. Huang ◽  
A. I. Nazzal ◽  
Y. Tokura ◽  
J. B. Torrance ◽  
R. Karimi
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Figure Of Merit ◽  
Systematic Errors ◽  
Structure Parameters ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Experimental Diffraction Pattern ◽  
Diffraction Peaks

AbstractAn ordered oxygen-deficient tetragonal perovskite compound La1.67Sr0.33Cu205 has been synthesized by solid state reaction. X-ray powder diffraction was used to characterize the material. Unit cell parameters least-squares refined from non-overlapping diffraction peaks are a = 10.8696(9)Å, c = 3.8612(6)Å and V = 456.2(1)Å3. X-ray powder data have been obtained for the experimentally observed peak positions corrected for systematic errors, the relative intensities, values of dexp and the Miller indices of both resolved and overlapping reflections. The experimental diffraction pattern was compared to computer simulated patterns calculated from the neutron crystal structure parameters and the non-oxygen-deficient LaCuO3 compound. The figure of merit is F30 = 33.8 (0.018, 48).

Method of Simulation of Diffraction Pattern for Nanosize Crystalline Systems

2008 ◽  
Vol 3 (4) ◽  
pp. 47-51
Author(s):  
Dmitriy A. Yatsenko ◽  
Sergey V. Tsybulya
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
X Ray ◽  
Original Algorithm ◽  
Diffraction Peaks ◽  
Diffraction Patterns ◽  
Definition Of ◽  
Integrated Intensities

The original algorithm and the software for calculation of x-ray powder diffraction patterns from ensemble of nanocrystal particles are developed. Test calculations are carried out. Errors in definition of positions, integrated intensities and halfwidth of diffraction peaks are estimated.

Synthesis and crystal structure refinement of new perovskite oxides, Dy0.55Sr0.45Mn1−xFexO3 (x = 0.0 and 0.2) from X-ray powder diffraction data

2016 ◽  
Vol 31 (4) ◽  
pp. 285-287 ◽  
Author(s):  
K. Yadagiri ◽  
R. Nithya
Keyword(s):  
Powder Diffraction ◽  
Room Temperature ◽  
Structure Refinement ◽  
Diffraction Profile ◽  
Synthesis And Crystal Structure ◽  
Ceramic Method ◽  
X Ray ◽  
Orthorhombic Cell ◽  
Diffraction Peaks ◽  
Profile Refinement

Polycrystalline compounds of Dy0.55Sr0.45Mn1−xFexO3 (x = 0.0 and 0.20) were synthesized using ceramic method and characterized by X-ray powder diffraction technique using CuKα (1.5406 Å) radiation at room temperature. All the diffraction peaks were indexed to an orthorhombic cell with space group Pnma (#62). Whole powder diffraction profile refinement was performed using GSAS package.

Combined XRD and XRF Analysis for Portable and Remote Applications

1994 ◽  
Vol 38 ◽  
pp. 319-324
Author(s):  
Jonathan A. Kerner ◽  
Edward D. Franco ◽  
John Marshall
Keyword(s):  
Powder Diffraction ◽  
Tilt Angle ◽  
Single Photon ◽  
Fluorescence Analysis ◽  
Low Energy ◽  
Energy Limit ◽  
Pure Sample ◽  
X Ray ◽  
Diffraction Peaks ◽  
Prototype Instrument

Abstract A prototype instrument, which provides x-ray powder diffraction and x-ray fluorescence analysis in a compact unit, has been developed to support the needs of NASA for planetary exploration. The instrument uses a 9-watt Fe-anodc x-ray tube and CCD in a fixed geometry for recording powder patterns with a 2θ range of 35°. The fluorescence spectrum for elements below Fe is collected simultaneously with the diffraction data. A shuttered Cd-109 isotopic source with emissions at 22 and 80 keV is used to excite higher energy fluorescence. The low-energy limit for discriminating single photon events was found to be ∼1.5 keV. Al-K could be distinguished from a pure sample, but the spectrum below 6 keV was degraded by the read noise of the CCD, which introduced spectral artifacts. Diffraction peaks from halite had a FWHM of ∼1°(2θ), with major contributions to the width from the use of slit collimation on the source and the low tilt angle of the sample.

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