Abstract: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, (Ba0.75Sr0.25)Ti1-δO3-2δ ceramics transform from single phase solid solutions with typical cubic perovskite structure to multiphase compounds while (Ba0.75Sr0.25)Ti0.998O2.996 ceramics remain to be single-phase with the increasing Sb2O3 content. The distortion of the ABO3 perovskite lattice caused by VTi″″ and induces the drop of Curie temperature and the rise of relative dielectric constant in (Ba0.75Sr0.25)Ti1-δO3-2δ ceramics with increasing δ value. The orientation of 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 (Ba0.75Sr0.25)Ti0.998O2.996 ceramics decrease dramatically while the dielectric loss increases.

Key words: barium strontium titanate; defects; dielectric properties; non-stoichiometric ceramics