Low-temperature sintering and electrical properties of (K, Na)NbO3 based lead-free ceramics with high Curie temperature

Lead-free ceramics (1 − x)(K0.48Na0.52)NbO3–(x/5.15)K2.9Li1.95Nb5.15O15.3 (x = 0.3–0.6, KNN–KLN100x) were prepared by conventional sintering technique at a low temperature of 960 °C. The effects of KLN contents on microstructure, dielectric, and piezoelectric properties were investigated. After the addition of KLN, the sintering performance and Curie temperature of the ceramics were markedly improved. The ceramics with x = 0.3 exhibited very good piezoelectric properties: d33 = 138 pC/N, kp = 45.03%, Tc = 495 °C, the dielectric constant at room temperature ɛr (RT) = 478 and the maximum dielectric constant ɛr (max) = 5067. These results indicated that the KNN–KLN100x lead-free ceramics sintered at low temperatures are promising for high temperature piezoelectric applications.