Reduction of oxygen vacancy concentration and large enhancement of electrical performances in Cu/Sb co-doped Bi4Ti3O12 high temperature piezoelectric ceramics

High oxygen vacancy concentration produced by bismuth volatilization during the sintering process has become one of the most important obstacles for the practical applications of Bi4Ti3O12 (BIT)-based high temperature piezoelectric ceramics. In this work, Cu and Sb were selected to modify the oxygen vacancy concentration and the electrical properties of the BIT ceramic. The crystal structure, microstructure, electrical conduction behaviors, and piezoelectric properties of Bi4Ti3 − x(Cu1/3Sb2/3)xO12 (BTCS) (x = 0, 0.01, 0.02, 0.03, 0.035, 0.04, and 0.05) ceramics were investigated in detail. Codoping significantly reduced the oxygen vacancy concentration and resulted in enhanced electrical resistivity along with improved piezoelectric properties. The BTCS ceramic with x = 0.035 exhibited optimized comprehensive performances such as a remarkable DC resistivity of 1.40 × 107 Ω cm at 500 °C and a relatively large piezoelectric coefficient (24 pC/N). Furthermore, the ceramic also showed good thermal stability of the piezoelectric coefficient and an excellent fatigue behavior. These results demonstrate the great potentials of Cu/Sb codoped BIT ceramics for piezoelectric device applications at high temperatures up to 500 °C.