A central peak in light scattering from the relaxor-type ferroelectric Na_1/2Bi_1/2TiO₃

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• 作者：Siny ; I.G. ; Husson ; E. ; Beny ; J.M. ; Lushnikov ; S.G. ; Rogacheva ; E.A. ; Syrnikov ; P.P.
• 关键词：77.80.&minus ; e ; 77.80.Bh ; 64.60.Ht ; 78.30.&minus ; j ; Phase transitions ; Ferroelectrics ; Raman scattering
• 刊名：Physica B
• 出版年：2001
• 期刊代码：53_09214526
• 类别：ph
• 出版时间：January, 2001
• 卷：293
• 期：3-4
• 页码：382-389
• 文件大小：151 K

摘要

A complex perovskite-type single crystal Na_1/2Bi_1/2TiO₃ (NBT) has been studied by Raman scattering. A broad central component has been revealed to analyze the temperature dependence of its intensity and width for the first time. The central component has features of a relaxation mode with the highest intensity in the intertransition region, so it arises from a critical light scattering on fluctuations of two coupled order parameters. The correlations between the central component behaviour, acoustic anomalies and dielectric response as well as their relation to a model with competing interactions are discussed. It is suggested that the broad central peak component in light scattering is characteristic of the relaxor-type ferroelectrics with a sequence of phase transformation irrespective of whether transitions are really observed as in NBT or whether transitions are frustrated under normal conditions as in PbMg_1/3Nb_2/3O₃ (PMN).