Smirnov M, Saint-Grégoire P
Faculty of Physics, St Petersburg State University, Petrodvoretz, 194508 St Petersburg, Russia.
Laboratoire MIPA, University of Nîmes, 30021 Nîmes cedex, France.
Acta Crystallogr A Found Adv. 2014 May;70(Pt 3):283-90. doi: 10.1107/S2053273314003994. Epub 2014 Apr 1.
Tetragonal tungsten bronze (TTB) oxides are one of the most important classes of ferroelectrics. Many of these framework structures undergo ferroelastic transformations related to octahedron tilting deformations. Such tilting deformations are closely related to the rigid unit modes (RUMs). This paper discusses the whole set of RUMs in an ideal TTB lattice and possible crystal structures which can emerge owing to the condensation of some of them. Analysis of available experimental data for the TTB-like niobates lends credence to the obtained theoretical predictions.
四方钨青铜（TTB）氧化物是最重要的铁电体类别之一。这些框架结构中的许多都会经历与八面体倾斜变形相关的铁弹性转变。这种倾斜变形与刚性单元模式（RUMs）密切相关。本文讨论了理想TTB晶格中的整套RUMs以及由于其中一些RUMs的凝聚可能出现的晶体结构。对类TTB铌酸盐现有实验数据的分析证实了所获得的理论预测。
