Acta Crystallographica Section B

Structural Science

Volume 59, Part 4 (August 2003)

research papers

Acta Cryst. (2003). B59, 463-471 [ doi:10.1107/S0108768103010073 ]

Ordered double perovskites - a group-theoretical analysis

C. J. Howard, B. J. Kennedy and P. M. Woodward

Abstract: Group-theoretical methods are used to enumerate the structures of ordered double perovskites, A₂BB'X₆, in which the ordering of cations B and B' into alternate octahedra is considered in combination with the ubiquitous BX₆ (or B'X₆) octahedral tilting. The cation ordering on the B-cation site is described by the irreducible representation of the $Pm \overline 3 m$ space group of the cubic aristotype, while the octahedral tilting is mediated by irreducible representations and . There are 12 different structures identified, and the corresponding group-subgroup relationships are displayed. Known structures are briefly reviewed.

Keywords: ordered perovskites; octahedral tilting; group-theoretical analysis.