Modification of both d33 and TC in a potassium–sodium niobate ternary system

Abstract

In this work, we simultaneously achieved a giant d₃₃ and a high T_C in a lead-free piezoelectric ternary system of (1 − x − y)K_0.48Na_0.52NbO₃–xBiFeO₃–yBi_0.5Na_0.5ZrO₃ {(1 − x − y)KNN–xBF–yBNZ}. Owing to the rhombohedral–orthorhombic–tetragonal (R–O–T) phase coexistence and the enhanced dielectric and ferroelectric properties, the ceramics with a composition of (x = 0.006, y = 0.04) show a giant d₃₃ of ∼428 pC N⁻¹ together with a T_C of ∼318 °C, thereby proving that the design of ternary systems is an effective way to achieve both high d₃₃ and high T_C in KNN-based materials. In addition, a good thermal stability for piezoelectricity was also observed in these ceramics (e.g., d₃₃ > 390 pC N⁻¹, T ≤ 300 °C). This is the first time such a good comprehensive performance in potassium–sodium niobate materials has been obtained. As a result, we believe that this type of material system with both giant d₃₃ and high T_C is a promising candidate for high-temperature piezoelectric devices.