New potassium–sodium niobate ternary system with large piezoelectric coefficient and high Curie temperature

In this paper, a new potassium–sodium niobate ternary system (0.96 − x)Ka0.48Na0.52NbO3–0.04Bi0.5Na0.5ZrO3–xBiAlO3 [(0.96 − x)KNN–0.04BNZ–xBA] with large piezoelectric coefficient (d33) and high Curie temperature (TC) simultaneously was attained due to the movement of orthorhombic–tetragonal phase transition temperature (TO–T) to room temperature and the enhanced dielectric properties. Especially, the ceramics with a composition of x = 0.005 show a large d33 of ~355 pC/N together with a high TC of ~335 °C. And moreover, a good thermal stability of d33 (e.g., d33 ≥ 316 pC/N, T ≤ 300 °C) was also observed in the ternary ceramics. Such a good comprehensive performance of d33 and TC attained in this work is superior to many reported results in the KNN-based materials. As a result, it was believed that this potassium–sodium niobate system with both large d33 and high TC will become one of the promising materials in the practical application.