Crystal Structure and Magnetic Properties of B-Site Ordered Perovskitetype Oxides A2CuBO6 (A=Ba, Sr; B=W, Te)

Four cuprate perovskites with the general formula A2CuBʹO6 (A=Ba, Sr; Bʹ=W, Te) were synthesized and the structural and 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 WO6 (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 ab-plane.