Cycling‐ and heating‐induced evolution of piezoelectric and ferroelectric properties of CuO‐doped K0.5Na0.5NbO3 ceramic

Abstract

AbstractFor accepter‐doped perovskite piezoelectric ceramics, macroscopic properties of the materials (eg, hardening, fatigue, and aging) are closely related to microscopic characteristics (eg, oxygen vacancies and defect dipoles). In this work, the relationship of macroscopic and microscopic characteristics in CuO‐doped K0.5Na0.5NbO3 (KNN) ceramic has been studied by subjecting the material to electric field cycling, quenching, heating, and consequently aging. The introduction of CuO in KNN generates and . The defect dipoles exhibit obviously the pinning effect on ferroelectric domains and thus induce a completely pinched/double P‐E loop and excellent hardening piezoelectricity of high Qm of 2235. With the destruction of short‐range symmetry uniformity between defect dipoles and ferroelectric dipoles induced by electric field cycling, quenching and heating, the ceramic can be depinned and softened. As a result, the depinned ceramic possesses an opened single ferroelectric hysteresis loop and the significantly decreasing Qm. A distinctive aging is observed in the depinned ceramic. This study provides deep insights into the evolution of electrical properties of accepter‐modified alkali niobate perovskite ceramics under electric field cycling, quenching, and heating.