Piezoelectric properties of (Li, Ag) modified (Na 0.50K 0.50)NbO 3 lead-free ceramics with high Curie temperature

Abstract

Lead-free piezoelectric ceramics (1 − x)[(Na 0.4725K 0.4725)Li 0.055]NbO 3– x(Ag 0.5Li 0.5)NbO 3 [(1 − x)KNNL– xALN] have been prepared by the conventional mixed oxide method. The ceramics show good piezoelectric and ferroelectric properties. Effect of the amount of (Ag 0.5Li 0.5)NbO 3 (ALN) on the phase structure, microstructure, piezoelectric and ferroelectric properties of (1 − x)KNNL– xALN ceramics were systematically investigated. It is found that the samples with 1 mol% ALN exhibit good piezoelectric and ferroelectric properties, and high Curie temperature. For (1 − x)KNNL– xALN ( x = 0.01) ceramics, the piezoelectric constant d 33 and Curie temperature T c reach 220 pC/N and 476 °C, respectively; the electromechanical coupling coefficient of the planar mode k p reaches 37%; the remnant polarization ( P r) is 22.4 μC/cm 2 with a coercive field ( E c) of 11.3 kV/cm. These results show that the (1 − x)KNNL– xALN is a promising candidate for high temperature lead-free piezoelectric ceramics.