Potassium–sodium niobate lead-free ceramics: modified strain as well as piezoelectricity

Abstract

The obvious conflicts between large piezoelectricity and high strain could be solved by developing new phase boundaries in potassium–sodium niobate materials. Here, we have solved this problem by extensive experimental researches and induced a larger strain as well as a higher piezoelectricity in (K, Na)NbO₃. Large converse piezoelectric coefficient (d^*₃₃ = 599–1553 pm V⁻¹) and high strain (0.18–0.46%) were achieved, which are the highest values reported to date in potassium–sodium niobate, suggesting that such a system is a promising lead-free candidate for electromechanical actuator applications. In addition, high d₃₃ values of 400–490 pC N⁻¹ have also been attained in the ceramic due to its rhombohedral–tetragonal phase boundary, as well as its composition.