The two-step sintering effect on the dielectric and piezoelectric properties of (Na,K)NbO 3 -BiScO 3 lead-free ceramics

Abstract

Abstract In this paper, the two-step sintering process was employed to lower the sintering temperature and improve the dielectric and piezoelectric properties of 0.98(Na 0.5 K 0.5 )NbO 3 −0.02BiScO 3 (0.98NKN-0.02BS) ceramics. By introducing the two-step sintering process for 0.98NKN-0.02BS ceramics, the volatilization of Na and K can be decreased. Dopants of Na and K have low-melting-point. By optimizing the dwelling time as 24 h in the two-step sintering process, the dielectric permittivity was enhanced up to 1287 at 1 kHz, while that of conventionally sintered ceramics is only 1201. By introducing the two-step sintering process, piezoelectric charge coefficient, piezoelectric voltage coefficient, electromechanical coupling factor were improved from 156 pC/N, 14.3 10 −3 Vm/N, 39.9% to 168 pC/N, 14.7 10 −3 Vm/N, 42.7%, respectively. We expect to enhance the dielectric and piezoelectric properties of 0.98Na 0.5 K 0.5 NbO 3 −0.02BiScO 3 lead-free piezoelectric ceramics by employing the two-step sintering process.