Effects of Mo2/3Bi1/3 doping on the phase structure, microstructure, and piezoelectric properties of KNNS–BNZ ceramics

0.97(K0.48Na0.52)(Mo2/3Bi1/3)xNb0.97−xSb0.03O3–0.03Bi0.5Na0.5ZrO3 lead-free piezoceramics were prepared by a conventional solid-state reaction route, and the effects of (Mo2/3Bi1/3)5+ on their phase structures, microstructures, and piezoelectric properties were studied. All the samples possess a pure perovskite structure. The coexistence of rhombohedral-orthorhombic-tetragonal phases was observed in all the ceramics. With the increase of x, their TO–T gradually decreases and diffuses and their TR–O slightly increases, while their TC almost keeps unchanged. The ceramics with x=0.004 show the enhanced piezoelectric properties (d33 ~389 pC/N, kp ~0.43, and TC ~285 °C). We believe that the addition of (Mo2/3Bi1/3)5+ is an effective way to enhance the piezoelectric properties of KNN-based ceramics.