Anion order in perovskites: a group-theoretical analysis

作者：Talanov M V; Shirokov V B; Talanov V M

来源：Acta Crystallographica A-Foundation and Advances, 2016, 72(2): 222-235.

DOI：10.1107/S2053273315022147

<jats:p>Anion ordering in the structure of cubic perovskite has been investigated by the group-theoretical method. The possibility of the existence of 261 ordered low-symmetry structures, each with a unique space-group symmetry, is established. These results include five binary and 14 ternary anion superstructures. The 261 idealized anion-ordered perovskite structures are considered as aristotypes, giving rise to different derivatives. The structures of these derivatives are formed by tilting of<jats:italic>B</jats:italic>O<jats:sub>6</jats:sub>octahedra, distortions caused by the cooperative Jahn–Teller effect and other physical effects. Some derivatives of aristotypes exist as real substances, and some as virtual ones. A classification of aristotypes of anion superstructures in perovskite is proposed: the<jats:italic>AX</jats:italic>class (the simultaneous ordering of<jats:italic>A</jats:italic>cations and anions in cubic perovskite structure), the<jats:italic>BX</jats:italic>class (the simultaneous ordering of<jats:italic>B</jats:italic>cations and anions) and the<jats:italic>X</jats:italic>class (the ordering of anions only in cubic perovskite structure). In most perovskites anion ordering is accompanied by cation ordering. Therefore, the main classes of anion order in perovskites are the<jats:italic>AX</jats:italic>and<jats:italic>BX</jats:italic>classes. The calculated structures of some anion superstructures are reported. Comparison of predictions and experimentally investigated anion superstructures shows coherency of theoretical and experimental results.</jats:p>

• 出版日期2016-3