Effect of Bi2O3 and Ho2O3 co-doping on the dielectric properties and temperature reliability of X8R BaTiO3-based ceramics

Abstract

Bi2O3 and Ho2O3 co-doped BaTiO3 (BT)-based X8R ceramics were successfully synthesized by the conventional solid-state reaction route. The synergistic effects of Bi3+ and Ho3+ co-doping on the dielectric performance and microstructures of BT-based ceramics were studied. The results show that by carefully adjusting the Bi2O3 and Ho2O3 doping concentrations, the temperature stability of the dielectric permittivity in BT-based ceramics can be significantly improved. Co-doped samples with 0.75%–1.5 mol% Bi2O3 and Ho2O3 meet the X8R specification. In particular, the 0.75 mol% Bi2O3 and 0.75 mol% Ho2O3 co-doped BT-based ceramics exhibit an optimum dielectric permittivity and a satisfactory temperature coefficient of capacitance (TCC) stability: the dielectric permittivity and dielectric losses are 2668 and 1.35% respectively at room temperature, the TCC at −55 °C and 150 °C is −0.92% and −9.56%, respectively. Transmission electron microscopy (TEM) analysis confirmed the formation of a core-shell microstructure in Bi2O3 and Ho2O3 co-doped BT-based ceramics. The synergistic effect of Bi3+ and Ho3+ co-doping plays a vital role in the production of the core–shell microstructure, which in turn is the main reason for the effective improvement of the TCC stability of BT-based ceramics.