Sintering Behavior of KNN-BNKT Lead-free Piezoelectric Ceramics

0.975(K0.5Na0.5)NbO3–0.025Bi0.5(Na0.9K0.1)0.5TiO3 (0.975KNN-0.025BNKT) lead-free piezoelectric ceramics were prepared, and the effects of sintering temperature on the microstructure, density, and piezoelectric properties of the ceramics were investigated. It was found that sintering densification of the ceramics occurs within a narrow temperature range, when the sintering temperature slightly deviates from optimal one the density of the ceramics decreases apparently, and the deviation would lead to uneven distribution of Bi and Ti, which will also affect the microstructure and the piezoelectric properties of the ceramics. It is concluded that the sintering temperature is a very critical factor for the KNN-based ceramics.