A new method for determining parameters of the potential well of off-center atoms from EXAFS dataстатья
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Дата последнего поиска статьи во внешних источниках: 17 декабря 2015 г.
Аннотация: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.