Improvement of dielectric and energy storage properties in Bi(Mg1/2Ti1/2)O3-modified (Na1/2Bi1/2)0.92Ba0.08TiO3 ceramics

Dielectric materials with stable dielectric and energy storage properties at a high operating temperature are needed in many important applications, such as the capacitors used in the automotive and aerospace industries. Between Td, the phase transition temperature from a ferroelectric phase to a high-temperature non-polar or weakly polar phase, and Tm, the maximum temperature of the dielectric constant, Na1/2Bi1/2TiO3-based ferroelectric materials exhibit a relatively small variation in their dielectric properties, a feature of this type of material. Here we will demonstrate that by incorporating Bi(Mg1/2Ti1/2)O3 into Na1/2Bi1/2TiO3-based ceramics, the temperature range between Td and Tm can be expanded, leading to a smaller variation of the dielectric and energy storage properties over a wider temperature range compared with the materials without modification. Bi(Mg1/2Ti1/2)O3 modification can also greatly increase the discharge energy density and charge-discharge efficiency of the materials. The 10 mol% Bi(Mg1/2Ti1/2)O3 modified (Na1/2Bi1/2)0.92Ba0.08TiO3 ceramics exhibit a small variation of dielectric constant and low loss from 100 °C to 400 °C. The materials also exhibit a high energy density (>2 J/cm3) and a high charge-discharge efficiency (>88%) at 120 °C. The energy density of the materials is almost independent of temperature from room temperature to 180 °C, which is attractive for high-temperature dielectric and energy storage applications.