ФТТ, 2005, том 47, выпуск 10

 Содержание  Предыдущая статья  Следующая статья  Поиск  

The lineshape of inelastic neutron scattering in the relaxor ferroelectrics

M.A.Ivanov, M.Koz\l ovski *, T.Piesiewicz *, V.A.Stephanovich **, A.Weron ***, A.Wymys\l owski ****

Institute of Metal Physics, Ukranian National Academy of Sciences, Kiev, Ukraine
* Institute of Power Systems Automation \& Laboratory for Interconnecting and Packaging Electronic Circuits,
Wroc\l aw University of Technology, Wroc\l aw, Poland
** Opole University, Institute of Mathematics and Informatics, Opole, Poland
*** Hugo Steinhaus Center for Stochastic Methods,
Wroc\l aw University of Technology, Wroc\l aw, Poland
**** Laboratory for Interconnecting and Packaging Electronic Circuits,
Wroc\l aw University of Technology, Wroc\l aw, Poland
E-mail: ivanov@imp.kiev.ua

(Received 4 November 2004
Revised 6 Februari 2005)

We show that a microscopic reason for a steep dropping of the optical phonon branch into the acoustic one (the so-called waterfall effect) in relaxor ferroelectrics may be the coupling of phonons with the defects and impurities of different kinds, which is always present in relaxors. Namely, we do not specify the type of impurities but rather represent them as an ensemble of so-called two-level systems (TLS). This approach permits to trace the evolution of the \glqq waterfall\grqq with temperature and the TLS concentration. To facilitate the planning of experiments on inelastic neutron scattering, we present a modification of the so-called Latin Hypercube Sampling method, which, based on some significance criteria, permits, to perform the measurements which are the most signeficant to elucidate the physical nature of, e. g., phonon dispersion laws in relaxor ferroelectrics.

Partial financial support was given to this work by the European Community 5th Framework Programme (MEVIPRO Project).

 PDF версия (486Kb)   Другие выпуски  Другие журналы   Помощь 
Copyright (C) 2005, Коллектив авторов  Разработано...  webmaster