Faculty of Physics
M.V.Lomonosov Moscow State University
Regular Article

New method for determining parameters of potential well of noncentral atoms using exafs spectroscopy

A.I. Lebedev, I.A. Sluchinskaya

Moscow University Physics Bulletin 2005. 60. N 6. P. 58

  • Article

A new method to determine parameters of a three-dimensional multiwell potential of noncentral 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 Sn$_{1-x}$Ge$_x$Te ($77\le T\le300$ K, $x\ge0.4$). It is shown that the anharmonic part of the potential is strongly anisotropic and that by its type a ferroelectric phase transition in Sn$_{1-x}$Ge$_x$Te is intermediate between the displacement and order—disorder transitions.

A.I. Lebedev, I.A. Sluchinskaya
Department of Semiconductor Physics, Faculty of Physics, Moscow State University, Leninskie Gory, Moscow, 119992, Russia
Issue 6, 2005

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