Lead-free ceramics (1 − x)(K1/2Na1/2)NbO3–xBi(Sc3/4Co1/4)O3 [(1 − x)KNN–xBSC] were prepared by the conventional solid-state sintering method. X-ray diffraction patterns show that the introduction of BSC into KNN system caused insignificant change in crystal structure. The composition with x = 0.015 has diphasic tetragonal and orthorhombic phases. Moreover, the grain size significantly dependent on the composition. The phase transition temperatures of orthorhombic–tetragonal (TO–T) and tetragonal–cubic (TC) decreased with increasing x from 0 to 0.025. The TO–T value of KNN–0.015BSC ceramic is close to room temperature, resulting in good electrical properties (d33 = 190 pC/N, kp = 40.3%, εr = 1494, tgδ = 0.026), with the Curie temperature TC = 321 °C. The combination of good piezoelectric properties and high TC makes these KNN–BSC ceramics suitable for elevated temperature piezoelectric devices.
