Piezoelectric properties of (Na0.5K0.5-xLix)NbO3 ceramics

Lead-free piezoelectric ceramics (Na0.5K0.5-xLix)NbO3 (x=0.057-0.066) were synthesized by an ordinary sintering technique. Substituting Li for K can lead to structural distortion, which improves the Curie temperature (T-C) greatly. By adding appropriate LiNbO3 content, piezoelectric constant d(33) values reach 202-212 pC/N. Electromechanical coefficients of the planar mode reach 44.4%-46.8%. The dielectric loss is below 2.6%, which is much lower than reported (about 50%). The T-C of (Na0.5K0.5-xLix)NbO3 (x=0.057-0.066) is in the range of 490-510 degrees C, at least 70 degrees C higher than that of pure (Na0.5K0.5)NbO3 ceramics. The results show that (Na0.5K0.5-xLix)NbO3 ceramic is a kind of good lead-free high-temperature piezoelectric material.