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

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.