Crystal structure of A2InSbO6 (A = Ca, Sr, Ba) ordered double perovskites

The structures of the perovskites Ca2InSbO6 (CISO), Sr2InSbO6 (SISO) and Ba2InSbO6 (BISO) have been investigated by X-ray diffraction. All three compounds have ordered double perovskite structure. The structures of the Ca2InSbO6 and Sr2InSbO6 perovskites can be best described by a monoclinic symmetry, space group P2(1)/n. The cell parameters are: a = 5.5273(1) angstrom, b = 5.6937(1) angstrom, c = 7.9049(2) angstrom, beta = 89.92(1)degrees for CISO, and a = 5.7327(1) angstrom, b = 5.7271(1) angstrom, c = 8.0979(1) angstrom, beta = 90.05(1)degrees for SISO. BISO can be described by the high-symmetry cubic doubled perovskite cell, space group Fm (3) over barm, with cell parameters a = 8.2938(1) angstrom. The degree of long range ordering as determined from the level of anti-site defects was 89%, 92% and 89% for CISO, SISO and BISO respectively. (C) 2010 Elsevier Masson SAS. All rights reserved.