Formation of BaPbO3-x and BaPb1/3Bi2/3O3-x from Ba(COO)2·0.5H2O and Pb(COO)2 oxalates

Abstract

This paper reports a way to obtain BaPbO3-x and BaPb1/3Bi2/3O3-x perovskite-type compounds. The method is based on the initial preparation of Ba(COO)2⋅0.5H2O and Pb(COO)2⋅oxalates, and the subsequent calcination of the equimolar physical mixture of these oxalates until the desired compounds BaPbO3-x and BaPb1/3Bi2/3O3-x are formed. To obtain BaPb1/3Bi2/3O3-x, the oxide Bi2O3 is added to the mixture of oxalates and calcined together with them. The temperature for the formation of BaPbO3-x and BaPb1/3Bi2/3O3-x was estimated to be 850°C. These final compounds prepared by calcination were composed of a single phase and exhibited monoclinic crystal structure. The thermal decomposition of the Pb(COO)2 oxalate and the formation of BaPbO3-x and BaPb1/3Bi2/3O3-x were investigated by X-ray powder diffraction (XRPD) and differential thermal analysis (DTA).