Effects of Li substitution and sintering temperature on properties of Bi0.5(Na,K)0.5TiO3 lead-free piezoelectric ceramics

Bi-0.5(Na0.72K0.28-xLix)(0.5)TiO3 (BNKLT-100x) lead-free piezoelectric ceramics are synthesized by conventional solid state sintering techniques. The dielectric and piezoelectric properties of the BNKLT-100x ceramics as a function of Li content are systematically investigated. It is found that not only Li content but also the sintering temperature has a strong effect on the piezoelectric properties of BNKLT. The piezoelectric constant d(33) of BNKLT varies from 120 to 252pC/N in the Li content range from 0.03 to 0.16. In the sintering temperature range from 1080 to 1130 degrees C, the d(33) value of BNKLT-6 changes from 200pC/N to 252pC/N. The BNKLT-6 sample sintered at 1100 degrees C has the highest piezoelectric constant d(33) of 252pC/N, with the electromechanical coupling factors kp of 0.32 and kt of 0.44.