The defect chemistry and dielectric properties of Sb2O3 doped non-stoichiometric barium strontium titanate ceramics

The microstructures and dielectric properties of Sb2O3 doped non-stoichiometric barium strontium titanate ceramics, prepared by solid state method, were investigated using XRD, SEM and LCR measure system. It is found that secondary phase and abnormal grain growth arise in the high Sb2O3 concentration doped non-stoichiometric barium strontium titanate ceramics. With the increase of Sb2O3 content, the relative dielectric constant at room temperature increases initially and then decreases while the dielectric loss at room temperature is determined by the concentration of oxygen vacancies and related defect complexes. The substitution preference of Sb3+ ion in non-stoichiometric barium strontium titanate ceramics changes according to the A-site ion/B-site ion mole ratio. The Curie temperature of (Ba0.7Sr0.3)Ti1.005O3.01 and (Ba0.7Sr0.3)Ti0.995O2.99 ceramics increases and then decreases as the Sb2O3 content increases. The temperature stability of the relative dielectric constant for high concentration Sb2O3 doped non-stoichiometric barium strontium titanate ceramics deteriorates due to the weakened grain boundary buffering effect.