Документ взят из кэша поисковой машины. Адрес оригинального документа : http://semiconductors.phys.msu.ru/publ/CRRS94.html
Дата изменения: Sat Jan 15 13:45:52 2005
Дата индексирования: Mon Oct 1 20:08:03 2012
Кодировка:
A new method for determining parameters of the potential well of off-center atoms from EXAFS Data The paper is published in Crystallography Reports, 49, Suppl. 1, pp. S94-S98 (2004).

A new method for determining parameters of the potential well of off-center atoms from EXAFS data

A.I. Lebedev, I.A. Sluchinskaya

Moscow State University, Vorob'evy gory, Moscow, 119992 Russia

Abstract

A new method is proposed that makes it possible to determine the parameters of the three-dimensional (3D) multiwell potential of off-center atoms from extended X-ray absorption fine-structure (EXAFS) data. The main features of this approach are the expansion of the 3D potential of a cluster in a power series of an atomic displacement taking into account the restrictions imposed by the lattice-site symmetry and exact 3D integration of the distribution function in calculations of EXAFS spectra. The parameters of the multiwell potential for Ge atoms in the Sn1-xGexTe solid solution as functions of temperature and composition (77<T<300 K, x>0.4) were obtained in the classical approximation. It is shown that the anharmonic part of the potential is highly anisotropic, and the type of ferroelectric phase transition in Sn1-xGexTe is intermediate between the displacive and order-disorder transitions.


Other works on XAFS studies