Lead-free piezoelectric ceramics （Na0.5K0.5-xLix）NbO3 （x=0.057-0.066） were synthesized by an ordinary sin-tering technique. Substituting Li for K can lead to structural distortion, which improves the Curie temperature （To） greatly. By adding appropriate LiNbO3 content, piezoelectric constant d33 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 To of （Na0.5K0.5-xLix）NbO3 （x=0.057-0.066） is in the range of 490-510℃, at least 70℃ 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.
Peng QI Jinfeng WANG Baoquan MING Juan DU Xinghua LIANG Limei ZHENG
This paper investigates the dielectric properties of （Na0.5K0.5Bi）0.5TiO3 crystal at intermediate frequencies （1kHz〈 f 〈IMHz） in the temperature range of 30-560℃. A pronounced high-temperature diffuse dielectric anomaly has been observed. This dielectric anomaly is shown to arise from a Debye-like dielectric dispersion that slows down following an Arrhenius law. The activation energy Er obtained in the fitting process is about 0.69eV. It proposes that the dielectric peak measured at low frequency above 400℃ is not related to the phase transition but to a space-charge relaxation.
