학술논문
Electron charge distribution of CaAl2− x Zn x : Maximum entropy method combined with Rietveld analysis of high-resolution-synchrotron X-ray powder diffraction data
Document Type
Article
Author
Source
Subject
*SYNCHROTRON radiation
*MAXIMUM entropy method
*LAVES phases (Metallurgy)
*WAVELENGTHS
*SOLID state chemistry
*CHARGE density waves
*RIETVELD refinement
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Language
ISSN
0022-4596
Abstract
Abstract: Using short wavelength X-rays from synchrotron radiation (SPring-8), high-resolution powder diffraction patterns were collected. In order to study both the structural relationship and the mechanism of stability in the CaAl2− x Zn x system, among the Laves phases (MgCu2 and MgNi2 type) and KHg2-type structures, the charge density distribution of CaAl2− x Zn x as a function of x was obtained from the diffraction data by Rietveld analysis combined with the maximum entropy method (MEM). In the MEM charge density maps overlapping electron densities were clearly observed, especially in the Kagomé nets of the Laves phases. In order to clarify the charge redistribution in the system, the deformation charge densities from the densities formed by the constituent free atoms are discussed. In the ternary MgNi2-type phase, partial ordering of Al and Zn atoms is observed, a finding that is supported by ab-initio total energy calculations. [Copyright &y& Elsevier]