New potassium-sodium niobate material system: A giant-d₃₃ and high-T_C lead-free piezoelectric

In this work, we elucidate the influence of Bi_0.5Li _0.5ZrO₃ (BLZ) content on the phase structure, microstructure, and electrical properties of (1 - x)K_0.40Na _0.60Nb_0.965Sb_0.035O₃-xBi _0.5Li_0.5ZrO₃ lead-free ceramics. We simultaneously achieved a giant d₃₃ and a high T_C in this material system. The coexistence of rhombohedral and tetragonal phases is responsible for such a large d₃₃ in the ceramics with BLZ contents (x) ranging from 0.025 to 0.035. Doping with BLZ not only induces the formation of the phase boundary, but also maintains a high T_C. The ceramic with x = 0.03 shows an enhanced piezoelectric behaviour (d₃₃ ∼ 400 pC N^-1 and k_p ∼ 0.47) together with a high T_C of 292°C. A good temperature stability for ferroelectricity and piezoelectricity is also observed in these ceramics. This study is the first time that such a good comprehensive performance has been obtained in potassium-sodium niobate materials. We believe that this type of material system possessing giant-d₃₃ and high-T_C is a promising candidate for use in high-temperature piezoelectric devices. This journal is