High mechanical quality factor and piezoelectricity in potassium sodium niobate ceramics

Abstract Plenty of works have done to enhance the piezoelectricity of potassium-sodium niobate (KNN), aiming to replace lead-zirconate titanate (PZT) in the consideration of eco-friendly requirement. However so far, KNN ceramics with high piezoelectric performances tend to have a low mechanical quality factor (Qm), which could result in excessive dielectric loss, especially when working in high frequencies. Thus, increasing Qm is a crucial task in KNN-based ceramics. By constructing phase boundaries together with inducing oxygen vacancies, a new KNN ceramic system is built by using conventional solid-state method with high Qm (>250), high piezoelectric performance as well as outstanding temperature stability. Optimum overall properties of KNN-based ceramics can be as large as d33 = 231 pC/N, Qm = 355, TC = 366 °C. This work provides a deeper insight to KNN-based ceramics with high mechanical quality factor and makes a progress on the high frequency application of lead-free ceramics.