A sub-lattice model for the incommensurate transition in A2BX4-type crystals

被引：3

作者：

Mashiyama, H ^{[1
]}

Shigematsu, H

机构：

[1] Yamaguchi Univ, Fac Sci, Dept Phys, Yamaguchi 7538512, Japan

[2] Nagoya Univ, Grad Sch Engn, Dept Quantum Engn, Nagoya, Aichi 4648603, Japan

来源：

FERROELECTRICS | 2002年 / 268卷

关键词：

two-sublattice model; soft mode; incommensurate transition; A(2)BX(4)-type crystal;

D O I：

10.1080/00150190211047

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

In order to describe a normal-incommensurate transition in A(2)BX(4)-type crystals, a two-sublattice model is presented, which is modified from the discrete four-sublattice model proposed recently by Ishibashi and Janssen (J. Phys. Soc. Jpn. 69 (2000) 3870). The new model describes the softening of an optical phonon branch connected to an acoustic branch in the extended zone scheme. The dispersion relation of the soft mode in K2SeO4 can be reproduced by terms up to the second-neighbor interactions, although the third-neighbor interactions are usually considered to be necessary.

引用

页码：95 / 100

页数：6

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