Low-Temperature Sintering of ZnO and B2O_3 Co-doped (K_0.5Na_0.5)NbO_3 Lead-Free Piezoelectric Ceramics

摘要

Lead-free K_0.5Na_0.5NbO_3-xwt% (0.4ZnO-0.6B2O_3) ceramics were synthesized by conventional ceramics process. The co-doping of ZnO and B2O_3 can decrease the sintering temperature of K_0.5Na_0.5NbCb ceramics to 1000°C, and the samples show high relative density around 96%. X-ray diffraction (XRD) reveals that Co-doping of ZnO and B2O_3 induces lattice distortion. Liquid phase is observed by scanning electron microscopy (SEM), which is resulted from the addition of ZnO and B2O_3. The ceramics show better piezoelectric and dielectric properties with planar electromechanical coupling factor kp= 40.7%, piezoelectric constant d_33= 117pC/N, dielectric constant ε~T3/eo=318.6, and loss tangent tan<5=0.034.