The two-step sintering effect on the dielectric and piezoelectric properties of (Na,K)NbO3-BiScO3 lead-free ceramics

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(Na0.5K0.5)NbO3−0.02BiScO3 (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 0.98Na0.5K0.5NbO3−0.02BiScO3 lead-free piezoelectric ceramics by employing the two-step sintering process.