High-Temperature Electrical Conduction Mechanisms in Donor-Doped Bi4Ti3O12 Aurivillius Piezoceramics: Role of Oxygen Vacancies

Donor doping has always been the most simple, effective, and most common method to exploit outstanding performance of Bi4Ti3O12 (BIT) high-temperature piezoceramics. Among various property parameters, the high-temperature electrical insulation characteristic is a particularly important nature, which is an important guarantee for the steady and reliable operation of BIT-based ceramics at high temperature. But, the electrical conduction mechanisms of donor-doped BIT ceramics at high temperature are still unclear. Herein, the high-temperature conduction mechanisms of Bi4Ti2.98(WNb)(0.01)O-12 (BITWN) ceramics under different atmospheres are studied systematically and its high-temperature conduction mechanisms are revealed for the first time. It is found that the high-temperature conducting process of BITWN ceramics presents different conduction mechanisms under different atmospheres. BITWN exhibits n-type and ionic conduction in the Ar atmosphere, whereas it is p-type and ionic conduction in the O-2 atmosphere, which is closely related to oxygen vacancy defects. The work subverts the prior cognition that the conduction mechanism of BIT-based ceramics simply belongs to p-type, and more importantly, provides the theoretical foundation for how to control the working atmosphere of donor-doped BIT ceramics to obtain excellent electrical insulation in practical application.