An effective optimization strategy and analysis for BaTiO 3 –Na 0.5 Bi 0.5 TiO 3 system with colossal permittivity

Abstract Colossal permittivity (CP, e＞10 4 ) behavior in BaTiO 3 –Na 0.5 Bi 0.5 TiO 3 (BT-NBT) ceramics has been studied, which showed extremely high permittivity up to ~10 5 . Dielectric properties of samples showed Debye-like relaxations in the frequency range 20 Hz–30 MHz. 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. By using defect engineering, a Nb-doped BaTiO 3 ceramics with stable colossal permittivity (e r =1.3×10 4 at 1 kHz and room temperature)，high bulk resistivity (>10 10 Ω·cm) as well as relative low dielectric loss (tanδ~0.06) has been obtained over a wide temperature range of −55–150 °C, satisfying IEA X8R specification, which has a potential application prospect in high capacity solid supercapacitor.