An effective optimization strategy and analysis for BaTiO3–Na0.5Bi0.5TiO3 system with colossal permittivity

Colossal permittivity (CP, ε＞104) behavior in BaTiO3–Na0.5Bi0.5TiO3 (BT-NBT) ceramics has been studied, which showed extremely high permittivity up to ~105. Dielectric properties of samples showed Debye-like relaxations in the frequency range 20Hz–30MHz. Two different polarizations located in grain boundaries and grains respectively are responsible for the CP behavior and the models of defect charge compensation achieved by niobium doping are proposed to explain the phenomenon of abnormal variation of dielectric constant.