On the phase formation mechanism of BaTiO3-SrTiO3 solid solution through solid – oxide reaction

Abstract

The formation of solid solution composition Ba0.5Sr0.5TiO3, from BaCO3, SrCO3 and TiO2 powders has been studied through solid oxide reactions using TGA/DSC, XRD. BaCO3 decomposes at much lower temperature in the mixture due to the presence of acidic TiO2. BaTiO3 (BT) and SrTiO3 (ST) start forming from the temperature 700OC and 800OC respectively without formation of BaO/SrO or any titanate phases. Rietveld refinement shows the rate of formation of BT is relatively higher than that of ST. The solid solution Ba0.5Sr0.5TiO3 (BST (ss)) starts forming from 1000OC. The rate of formation of BaTiO3 is higher than that of SrTiO3¬. Activation energy for formation of BaTiO3 (40.41 kcal/mol) is higher than that of SrTiO3 (58.867 kcal/mol) in the system. Lattice parameter of initial solid solution phase is higher indicating that the BST forms with the interface of BT. The final BST (ss) formation requires more activation energy (76.999 kcal/mol) than initial BT and ST