Temperature dependence on the piezoelectric property of (1 − x)(Na0.5K0.5)NbO3–xLiNbO3 ceramics

Lead-free (1 − x)(Na0.5K0.5)NbO3–xLiNbO3 ((1 − x)NKN−xLN) piezoelectric ceramics have been synthesized by solid state sintering between x = 0.040 and 0.080. The effects of temperature on the dielectric, ferroelectric and piezoelectric properties were investigated. For all the samples measured, the remanent polarization (Pr) and coercive field (Ec) showed a tendency of reduction with increasing temperature, but a planer-mode electromechanical coupling coefficient (kp) and frequency constant (Np) varied in non-linearity as a function of temperature. The temperature dependence of the piezoelectric properties of (1 − x)NKN–xLN ceramics was strongly affected by the lithium content, too. The kp values enhanced at the tetragonal–orthorhombic phase transition temperature for all the specimens with different Li contents due to the MPB effects. Especially for the x = 0.055 and 0.060 sample, the variation of elastic compliance also affected their piezoelectric property.