Achieving ultra-high resistivity and outstanding piezoelectric properties by co-substitution in CaBi2Nb2O9 ceramics

CaBi2Nb2O9 (CBNO) ceramics exhibit significant potential in the development of piezoelectric sensors suitable for extreme environments such as aerospace, metallurgy, and nuclear power plants. While previous studies have enhanced the piezoelectric response of CBNO ceramics, their insulating properties at high temperatures still require improvement. In this work, co-substitution of (Li0.5Bi0.5) at A site and Mn at B site was designed to improve the electrical properties of CBNO ceramics. Defect dipoles induced by the bound between Mn and oxygen vacancies restrict the movement of oxygen vacancies at high temperatures. Meanwhile, co-substitution of Ca by (Li0.5Bi0.5) reduces both the sintering temperature and volatilization of Bi2O3 during the sintering process. This modification results in an ultra-high TC of 928 °C and an exceptional resistivity of 2.85 MΩ cm at 600 °C for Ca0.96(Li0.5Bi0.5)0.04Bi2Nb1.98Mn0.02O9 ceramics. Furthermore, the ceramic exhibits excellent piezoelectric properties (d33 of 15.2 pC/N and kp of 6.9 %), ferroelectric properties (Pr of 9.42 μC/cm2), and thermal stability (degeneration of d33 only 6 % after annealing at 900 °C for 2 h). This work offers a practical strategy for simultaneously achieving both a high piezoelectric response and outstanding insulating properties in the CBNO system. © 2024 Elsevier Ltd