title: Unified approach for determining tetragonal tungsten bronze crystal structures.
abstract: 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.
authors.affiliation: Faculty of Physics, St Petersburg State University, Petrodvoretz, 194508 St Petersburg, Russia.
authors.forename: M
authors.initials: M
authors.lastname: Smirnov
authors.affiliation: Laboratoire MIPA, University of Nîmes, 30021 Nîmes cedex, France.
authors.forename: P
authors.initials: P
authors.lastname: Saint-Grégoire
keywords: phase transitions; rigid unit modes; tetragonal tungsten bronzes