Reduce the low-frequency dielectric losses of (In0.5Nb0.5)0.05Ti0.95O2 ceramics by increasing grain boundary density and resistance

Abstract

(In0.5Nb0.5)0.05Ti0.95O2 (INTO) ceramics exhibits unusual colossal permittivity properties. However, the high dielectric loss limits their practical applications. Increasing the contribution of grain boundaries to dielectric properties can reduce their dielectric loss. Therefore, La was added to increase the number of grain boundaries, while annealing was performed to improve the grain boundary resistance. The results show that La addition and annealing in air indeed reduce the grain size of INTO ceramics and low their dielectric loss due to increased grain boundary resistance. Specifically, the permittivity of annealed La-doped INTO ceramic remains at 2 × 104, and its dielectric losses are less than 0.05 from 30 Hz to 6.5 kHz, with a minimum of approximately 0.02. The dielectric loss at 1 kHz is below 0.05 from below −60 °C to about 90 °C. The effects of La-doping and annealing on INTO ceramics, as well as the origin of the colossal permittivity properties, were discussed.