Местоположение издательства:New York, N.Y., United States
Первая страница:58
Последняя страница:64
Аннотация:A new method to determine parameters of a three-dimensional multiwell potential of off-center atoms from EXAFS data has been proposed. The main features of this approach are the series expansion of a three-dimensional potential in a cluster in displacement degrees with allowance for constraints imposed by lattice-node symmetry and the exact three-dimensional integration of the distribution function in calculation of EXAFS spectra. Within the framework of this approach, parameters of a multiwell potential were estimated for the first time in classical approximation for a Ge atom in solid solution Sn1−xGexTe (77≤T≤300 K, x≥0.4). It is shown that the anharmonic part of the potential is strongly anisotropic and that by its type a ferroelectric phase transition in Sn1−xGexTe is intermediate between the displacement and order—disorder transitions.