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

Abstract

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)0.01O12 (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 O2 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.