Microstructure and piezoelectric properties of NaF-doped K0.5Na0.5Nb0.95Ta0.05O3 lead-free ceramics

The effects of NaF on the microstructure and electrical properties of K0.5Na0.5Nb0.95Ta0.05 lead-free ceramics prepared by conventional sintering method were investigated in this study. The dopant NaF effectively lowers the sintering temperature and promotes the grain growth. Samples with a high relative density up to 96.3 % are achieved by adding 0.6 wt% NaF to improve the sinterability. The electric properties are also enhanced, and the optimum properties are achieved at the doping content of 1.0 wt% (d(33) = 153 pC/N, k(P) = 32.2 %, Q(m) = 80.5, E-c = 0.89 kV/mm, and P-r = 16.5 mu C/cm(2)). The improvement of ferroelectric and piezoelectric properties is suggested to be largely contributed to the compensation of sodium element from dopant NaF for the volatilization of A-site alkali elements.