An improved method to determine the weight fraction of 2212 and 2201 phase impurities in BSCCO-2223 powders from x-ray powder diffraction peaks

A special computer storage method for chemical structures is illustrated in this article. With an improved method of two-dimensional connection table and topology, we can fit almost all chemical structures and display them very conveniently. We have used this method in the PDF (X-Ray Powder Diffraction File) database, which contains many special structures.Key words: database, computer application, chemical structure

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

Powder Diffraction ◽

10.1017/s0885715600015566 ◽

1990 ◽

Vol 5 (3) ◽

pp. 137-143 ◽

Cited By ~ 6

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.

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

Powder Diffraction ◽

10.1017/s0885715600016614 ◽

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.

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

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768103015441 ◽

2003 ◽

Vol 59 (5) ◽

pp. 647-652 ◽

Cited By ~ 5

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.

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

10.21203/rs.3.rs-506356/v1 ◽

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.

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

Powder Diffraction ◽

10.1017/s0885715616000312 ◽

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.

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

Powder Diffraction ◽

10.1017/s0885715600013270 ◽

1988 ◽

Vol 3 (2) ◽

pp. 81-83 ◽

Cited By ~ 4

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).

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A Dual Counter X-Ray Analyzer for the Rapid Quantitative Analysis of Two-Phase Systems

Advances in X-ray Analysis ◽

10.1154/s0376030800003542 ◽

1965 ◽

Vol 9 ◽

pp. 202-207

Author(s):

B. S. Sanderson ◽

L. E. MacCardle

Keyword(s):

Quantitative Analysis ◽

Lithium Fluoride ◽

Quantitative Measurement ◽

Improved Method ◽

Two Phase ◽

X Ray ◽

Normal Procedure ◽

Diffraction Peaks ◽

Phase Systems ◽

Two Phases

AbstractThe normal procedure for a quantitative measurement of two phases with an X-ray diffractoraeter is to scan or count the intensities of two diffraction peaks and then to calculate the ratio of the two phases using an appropriate equation. This paper will describe an improved method of quantitatively measuring two phases in a sample. The diffractometer, which was constructed by Philips Electronics Instruments, consists of two fixed scintillation counters mounted at the Seeman-Bohlin focusing positions for the two desired diffraction lines. Each counter is preceded by a lithium fluoride curved crystal monochromator. The output from each counter feeds to a separate sealer which can be arranged to gate both sealers at a preselected number of counts. At this point a tape printer prints out the counts for both sealers. These counts are then related to the proportions of each phase present by an appropriate equation. Most of the electronics are solid-state designs. This paper will describe the instrumentation and show how it can be used to measure rapidly and precisely the ratio of anatase to rutile in a titanium dioxide system. The savings in time over the conventional method can be as much as 100 to 1.

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Quantitative X-Ray Powder Diffraction Method Using the Full Diffraction Pattern

Powder Diffraction ◽

10.1017/s0885715600012409 ◽

1987 ◽

Vol 2 (2) ◽

pp. 73-77 ◽

Cited By ~ 92

Author(s):

Deane K. Smith ◽

Gerald G. Johnson ◽

Alexandre Scheible ◽

Andrew M. Wims ◽

Jack L. Johnson ◽

...

Keyword(s):

Diffraction Pattern ◽

Powder Diffraction ◽

Diffraction Method ◽

Weight Fraction ◽

Reference Database ◽

Weighted Sum ◽

X Ray ◽

Unique Approach ◽

Diffraction Patterns ◽

Best Fit

AbstractA new quantitative X-ray powder diffraction (QXRPD) method has been developed to analyze polyphase crystalline mixtures. The unique approach employed in this method is the utilization of the full diffraction pattern of a mixture and its reconstruction as a weighted sum of diffraction patterns of the component phases. To facilitate the use of the new method, menu-driven interactive computer programs with graphics have been developed for the VAX series of computers. The analyst builds a reference database of component diffraction patterns, corrects the patterns for background effects, and determines the appropriate reference intensity ratios. This database is used to calculate the weight fraction of each phase in a mixture by fitting its diffraction pattern with a least-squares best-fit weighted sum of selected database reference patterns.The new QXRPD method was evaluated using oxides found in ceramics, corrosion products, and other materials encountered in the laboratory. Experimental procedures have been developed for sample preparation and data collection for reference samples and unknowns. Prepared mixtures have been used to demonstrate the very good results that can be obtained with this method.

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