Temperature dependence of dielectric permittivity in incommensurately modulated phase of ammonium fluoroberyllate

被引:2
|
作者
Horon, B. I. [1 ,2 ]
Kushnir, O. S. [2 ]
Shchepanskyi, P. A. [1 ]
Stadnyk, V. Yo. [1 ]
机构
[1] Ivan Franko Natl Univ Lviv, Gen Phys Dept, 23 Drahomanov St, UA-79005 Lvov, Ukraine
[2] Ivan Franko Natl Univ Lviv, Optoelect & Informat Technol Dept, 107 gen Tarnavskyi St, UA-79013 Lvov, Ukraine
关键词
phase transitions; incommensurate phases; improper ferroelectrics; dielectric permittivity; ammonium fluoroberyllate; TRANSITION; CRYSTAL; (NH4)2BEF4; WEAK;
D O I
10.5488/CMP.25.43704
中图分类号
O469 [凝聚态物理学];
学科分类号
070205 ;
摘要
We study the temperature dependence of dielectric permittivity along the polar axis for ferroelectric ammonium fluoroberyllate (AFB) crystal in the vicinity of its phase transition points. The experimental data within incom-mensurately modulated phase of AFB is compared with the predictions of phenomenological models known from the literature: the Curie-Weiss (CW) law, the generalized Curie-Weiss (GCW) law, and the models by Le-vanyuk and Sannikov (LS) and by Prelovsek, Levstik and Filipic (PLF) suggested for improper ferroelectrics. It is shown that the LS approach describes the temperature behavior of the dielectric permittivity for the AFB crystal better than the CW, GWC and PLF models. The main physical reasons of this situation are elucidated.
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页数:12
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