Crystal structure and magnetic properties of B-site ordered perovskite-type oxides A2CuB′O6 (A = Ba, Sr; B′ = W, Te)

Four cuprate perovskites with the general formula A(2)CuB'O-6 (A = Ba, Sr; B' = W, Te) were synthesized and the structural acid the magnetic properties were investigated. Among four samples, perovskite Ba2CuTeO6 was formed only under high pressure. All the samples were tetragonally distorted B-site ordered perovskite-type oxides with I4/m symmetry. The CuO6 octahedra is elongated by the Jahn-Teller effect of Cu2+ ion and CuO6, and WO, (or TeO6,) octahedra rotates about the [001] direction, These compounds show two-dimensional antiferromagnetic behavior, because of the superexchange interaction between Cu2+ ions via an array of nonmagnetic ions, O-W-O (or O-Te-O) in the ab-plane perpendicular to the c-axis. The detailed analysis of the crystal structure made clear that the strength of the superexchange interaction depends more on the bond angle Cu-O-W (or Cu-O-Te) than the distance between Cu2+ ions in the abplane. (C) 1999 Academic Press.