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Title: Use of Bayesian Inference in Crystallographic Structure Refinement via Full Diffraction Profile Analysis

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
NSFUNIVERSITY
OSTI Identifier:
1314244
Resource Type:
Journal Article
Resource Relation:
Journal Name: Scientific Reports; Journal Volume: 6; Journal Issue: 2016
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Fancher, Chris M., Han, Zhen, Levin, Igor, Page, Katharine, Reich, Brian J., Smith, Ralph C., Wilson, Alyson G., and Jones, Jacob L.. Use of Bayesian Inference in Crystallographic Structure Refinement via Full Diffraction Profile Analysis. United States: N. p., 2016. Web. doi:10.1038/srep31625.
Fancher, Chris M., Han, Zhen, Levin, Igor, Page, Katharine, Reich, Brian J., Smith, Ralph C., Wilson, Alyson G., & Jones, Jacob L.. Use of Bayesian Inference in Crystallographic Structure Refinement via Full Diffraction Profile Analysis. United States. doi:10.1038/srep31625.
Fancher, Chris M., Han, Zhen, Levin, Igor, Page, Katharine, Reich, Brian J., Smith, Ralph C., Wilson, Alyson G., and Jones, Jacob L.. 2016. "Use of Bayesian Inference in Crystallographic Structure Refinement via Full Diffraction Profile Analysis". United States. doi:10.1038/srep31625.
@article{osti_1314244,
title = {Use of Bayesian Inference in Crystallographic Structure Refinement via Full Diffraction Profile Analysis},
author = {Fancher, Chris M. and Han, Zhen and Levin, Igor and Page, Katharine and Reich, Brian J. and Smith, Ralph C. and Wilson, Alyson G. and Jones, Jacob L.},
abstractNote = {},
doi = {10.1038/srep31625},
journal = {Scientific Reports},
number = 2016,
volume = 6,
place = {United States},
year = 2016,
month = 8
}
  • The refinement of crystal structure from powder diffraction data is separated into two independent steps: Profile Fitting and Least Squares Analysis. The method has been applied to the refinement of several crystal structures and has given low R-values, for example R = 0.37%, 1.57% and 1.76% for silicon, corundum and quartz resp.
  • Full-pattern fiber X-ray diffraction refinement has been used to study the structure and morphology of the crystallites of three poly(ethylene terephthalate) fiber samples with different heat treatment history. Diffraction data over the whole two-dimensional space were collected with a four-circle diffractometer. An iterative Fourier filter method is developed to separate the crystalline diffraction from the background scattering. Both the structure and morphology are found to be dependent on the heat treatment. Some properties of the fibers can be explained by the difference in the crystal structure and morphology of crystallites.
  • A technique of three-dimensional (3D) local structure refinement is proposed and demonstrated by applying it to the metal complex Ni(acacR){sub 2}. The method is based on the fitting of experimental x-ray absorption near-edge structure (XANES) using a multidimensional interpolation of spectra and full potential calculations of XANES. The low number of calculations required is the main advantage of the method, which allows a computationally time-expensive method using a non-muffin-tin potential to be applied. The possibility to determine bond angles in addition to bond lengths accessible to extended x-ray-absorption fine structure opens new perspectives of XANES as a 3D structure probe.
  • A full-profile analysis has been made of the x-ray diffraction patterns of lowtemperature forms of aluminum oxide. Structural models are proposed for these forms, describing the experimental data with a high confidence factor.
  • The crystal structure of the isomorphous phases Mg{sub 5}Nb{sub 4}O{sub 15} and Mg{sub 5}Ta{sub 4}O{sub 15} was refined from neutron powder diffraction data. These compounds are isostructural with pseudobrookite, Fe{sub 2}TiO{sub 5}. The two kinds of metal sites of this structure are randomly occupied by Mg(II) and Nb(V) or Ta(V). The structure consists of double chains of (Mg,M)O{sub 6} units (where M = Nb or Ta), sharing edges on the bc plane, interconnected through common oxygens along the a axis to give a three-dimensional array. The (Mg, M)O{sub 6} polyhedra at both metal positions can be described as very distortedmore » octahedra, with (Mg, M)-O distances ranging from 1.93 to 2.22 {angstrom}. The crystallographic formulas can be written as (Mg{sub 0.73(2)}Nb{sub 0.27(2)}){sub 4c} (Mg{sub 0.94(2)}Nb{sub 1.06(2)}){sub 8f}O{sub 5} and (Mg{sub 0.66(2)}Ta{sub 0.34(2)}){sub 4c}(Mg{sub 1.01(2)}Ta{sub 0.99(2)}){sub 8f}O{sub 5} respectively, where 4c and 8f are the Wyckoff sites of the two metal positions of the structure. The space group is Cmcm (orthorhombic) and Z = 4. Unit cell parameters, cell volume, R{sub wp} and R{sub I} values obtained were a = 3.8068(1) {angstrom}, b = 10.0561(1) {angstrom}, c = 10.2566(1) {angstrom}, V = 392.64(2) {angstrom}{sup 3}, and 6.72% and 2.94% for the niobium compound; and a = 3.81884(6) {angstrom}, b = 10.0574(2) {angstrom}, c = 10.2343(2) {angstrom}, V = 393.07(2) {angstrom}{sup 3}, and 4.46%, and 2.36% for the tantalum compound.« less