Dielectric properties and point defect behavior of antimony oxide doped Ti deficient barium strontium titanate ceramics

The microstructures and dielectric properties of Sb₂O₃-doped Ti deficient barium strontium titanate ceramics prepared by solid state method were investigated with non-stoichiometric level and Sb₂O₃ content by SEM, XRD and LCR measure system. It is found that with the increase of δ, (Ba_0.75Sr_0.25)Ti_1–δO_3–2δ ceramics transform from single phase solid solutions with typical cubic perovskite structure to multiphase compounds while (Ba_0.75Sr_0.25)Ti_0.998O_2.996 ceramics remain to be single-phase with the increasing Sb₂O₃ content. The distortion of the ABO₃ perovskite lattice caused by V_Ti″″ and V_o^?? induces the drop of Curie temperature and the rise of relative dielectric constant in (Ba_0.75Sr_0.25)Ti_1–δO_3–2δ ceramics with increasing δ value. The orientation of V_o^?? elastic dipoles results in the domain-wall pinning and thus the reduction of the dielectric loss. With increasing Sb₂O₃ content, the relative dielectric constant, dielectric constant maximum and Curie temperature of (Ba_0.75Sr_0.25)Ti_0.998O_2.996 ceramics decrease dramatically while the dielectric loss increases.