Local structure of copper nitride revealed by EXAFS spectroscopy and a reverse Monte Carlo/evolutionary algorithm approach

Extended X-ray absorption fine structure (EXAFS) and neutron scattering data from monoclinic zirconia are analysed independently and simultaneously by reverse Monte Carlo (RMC) modelling. X-ray and neutron powder diffraction data are analysed by Rietveld refinement. The results are compared with respect to the local structure around the zirconium cations. Monoclinic zirconia was chosen as a model system for the comparison of structural information obtained by EXAFS spectroscopy and scattering methods because it is crystalline but also has some local disorder. In the case of zirconia, analysis of EXAFS spectra by RMC modelling results in reliable and accurate information on the local structure, consistent with neutron scattering and diffraction experiments.

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Local Structure of Cobalt Tungstate Revealed by EXAFS Spectroscopy and Reverse Monte Carlo/Evolutionary Algorithm Simulations

Zeitschrift für Physikalische Chemie ◽

10.1515/zpch-2015-0646 ◽

2016 ◽

Vol 230 (4) ◽

Cited By ~ 6

Author(s):

Janis Timoshenko ◽

Andris Anspoks ◽

Aleksandr Kalinko ◽

Alexei Kuzmin

Keyword(s):

Monte Carlo ◽

Evolutionary Algorithm ◽

Broad Class ◽

Structural Parameters ◽

Processing Technique ◽

Exafs Spectroscopy ◽

Specific Method ◽

Reverse Monte Carlo ◽

Signal Processing Technique ◽

Cobalt Tungstate

AbstractEXAFS spectroscopy is an element-specific method that can provide perhaps the most extensive information on the local atomic structure and lattice dynamics for a broad class of materials. Conventional methods of EXAFS data treatment are often limited to the nearest coordination shells of the absorbing atom due to the difficulties in accurate accounting for the large number of correlated structural parameters that have to be included in the analysis. In this study we overcome this problem by applying novel simulation-based method: reverse Monte Carlo simulations, coupled with the evolutionary algorithm and with a powerful signal processing technique – wavelet transform. This complex approach was applied to the analysis of the W L

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Structure Evolution of Au50Cu50 Alloy from Melt to the Disordered Solid Solution

Materials Science Forum ◽

10.4028/www.scientific.net/msf.993.273 ◽

2020 ◽

Vol 993 ◽

pp. 273-280

Author(s):

Yan Wen Bai ◽

Xiao Lin Zhao ◽

Xiu Fang Bian ◽

Kai Kai Song ◽

Yan Zhao

Keyword(s):

Solid Solution ◽

Monte Carlo ◽

Local Structure ◽

Solution Structure ◽

Liquid Structure ◽

Structure Evolution ◽

Reverse Monte Carlo ◽

Diffraction Experiment ◽

X Ray Diffraction ◽

X Ray

The liquid local structure of Au50Cu50 solid solution was detected by high-temperature X-ray diffraction experiment and Reverse Monte Carlo (RMC) simulation. The clusters in the liquid Au50Cu50 alloy comprise the 12-coordinated polyhedron with Au center, which was the same as the clusters in the liquid pure Au. In the case of alloying, there was a high population of Au-Au bonds, and the local structure around Cu atoms was changed. In the case of solidification, the 12-coordinated clusters around Au atoms were preserved into the AuCu alloy, forming the disordered solid solution structure. The strong tendency for Cu-Cu bonds was weakened from 2.35 Å in the liquid to 2.81 Å in the solid solution, and the local structure around Cu atoms rearranges. It is shown that the liquid structure of the Au50Cu50 alloy plays a crucial role in the solid solution. Our findings elucidate that the disordered solid solution structure in AuCu alloy stems from the highly dominated 12-coordinated clusters associated with centered Au atom in the melt.

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