Lanthanum doping effect in barium strontium titanate glass ceramics

Lanthanum doping effect in barium strontium titanate (Ba,Sr)TiO3 (BST) glass ceramics has been investigated by differential scanning calorimeter (DSC), X-ray diffractometry and Raman spectroscopy. Studies were performed on specimens with lanthanum oxide (La2O3) concentrations between 0 and 1.0 mol% for BaO–SrO–TiO2–SiO2–Al2O3 glass system. The analysis of the dependence of DSC measurements on La2O3 concentration has shown that the increase of La2O3 concentration promotes the formation of the barium strontium titanate crystalline phase. The X-ray diffractometry results have demonstrated that the amount of barium strontium titanate crystalline phase increases and then decreases with the increase of the La2O3 concentration. The Raman spectrum results, which coincide with the X-ray diffractometry patterns, confirmed that lanthanum ions diffused into the lattice structure and modified the tetragonality of the barium strontium titanate phase. However, the additive of 1.0 mol% La2O3 may go beyond the solid solubility limit of lanthanum in the BST lattice.