New ordered perovskites containing bismuth (V) [BaLaMBiO6 (M = Mg, Ca, Sr)]

New Bi (V) containing perovskites oxides of the type, BaLaMBiO6 (M = Mg, Ca, Sr) have been synthesized under high oxygen pressure conditions using the thermal decomposition of peroxides in a tetrahedral anvil apparatus. These compounds have been characterized by X-ray powder diffraction and iodometric titration. All the BaLaMBiO6 (M = Mg, Ca, Sr) compounds show 1:1 type ordering of cations at the octahedral sites of the perovskite structure. In the case of magnesium and calcium containing perovskites, comparison of the observed and the calculated X-ray powder diffraction intensities show that the A sites are occupied by barium and lanthanum in a disordered manner, and the octahedral sites are occupied by an ordered arrangement of bismuth and magnesium or bismuth and calcium. This in contrast to strontium containing phase, where the A sites are found to be occupied by barium and strontium in a disordered arrangement and the octahedral sites are occupied by lanthanum and bismuth. The oxygen content, hence the oxidation state of Bi, in the samples depends on the synthetic conditions employed. The electrical properties of the synthesized materials are discussed briefly.