Relaxor behavior of potassium sodium niobate ceramics by domain evolution

Abstract

Relaxor behavior is proved to be responsible for high piezoelectricity in piezoelectric materials due to the promoted polarization rotation, and an ultrahigh piezoelectricity can be also induced in potassium sodium niobate [(K,Na)NbO3, KNN]-based ceramics by dielectric relaxation at the multiphase coexistence region. However, it is still absent of the association study between domain evolution and relaxor behavior created by nanoscale multiphase coexistence. Herein, the frequency-dependent domain response, dwell-time dependence of domain radius and voltage-dependent domain switching are characterized in KNN-based ceramics with relaxor R–T phase boundary. These novel domain evolutions further illustrate the contribution of relaxor behavior on high piezoelectricity, yielding to easy polarization rotation based on low energy barrier of polar nanoregions merging into long-range ordering states. And an improved temperature stability is observed at 30−60 °C for relaxor R–T due to the unusual domain evolution. This study affords a new perspective in the mechanism of high-performance lead-free piezoelectrics.