Gamma-ray promoted defects dipole migration and fast aging mechanism in KNN-based ceramics

Abstract

The property evolution of piezoelectric ceramics under extreme environments such as gamma irradiation still lacks research. Here, the evolution of structure and electrical properties for potassium sodium niobate [K, Na)NbO₃]-based ceramics under γ-ray irradiation was systematically investigated, with a focus on possible defect dipole migration mechanism. Compared with unirradiated ceramics, ceramics after irradiation have a stable d₃₃ and rapid increase of Q_m as well as a fast-aging phenomenon. This is attributed to the hardened domain walls, instead of the variation of domain structure and the number of defect dipoles. The internal defect dipoles (${\left[C{u}_{Nb}^{{}^{″\prime }}-V_O^{..}\right]}^{\prime }$) are at a lower energy position, which will move toward the domain walls and produce a strong pinning effect during irradiation. This work reveals the property evolution and corresponding defect dipole migration mechanism in the piezoceramics under gamma irradiation, provides basic understanding for piezo-devices operating in harsh environments.