Enhanced piezoelectric properties in potassium-sodium niobate-based ternary ceramics

(1 - x)K0.5Na0.5Nb1 - ySbyO3-zSrZrO(3)-xBi(0.5)Na(0.5)HfO(3) (KNNS-SZ-BNH) lead-free ceramics were developed by the conventional solid-state reaction method. Effects of the additives (Bi0.5Na0.5HfO3, SrZrO3 and Sb5+) on their phase structure, microstructure, and electrical properties were investigated. The rhombohedral-orthorhombic- tetragonal (R-O-T) phase boundary can be established in the ceramics with 0.03 <= x <= 0.05, 0.04 <= y <= 0.06, and 0.01 <= z <= 0.025, and then their piezoelectric properties were improved. The ceramics with x = 0.03, y = 0.04 and z = 0.01 possess the optimum piezoelectric properties (d(33) = 470 +/- 5 pC/N, k(p) = 0.51 +/- 0.02, and T-C = 244 degrees C). We believe that R-O-T multiphase coexistence is mainly responsible for the enhancement of piezoelectric properties. (C) 2016 Elsevier Ltd. All rights reserved.