Effect of sintering temperature and time on densification, microstructure and properties of the PZT/ZnO nanowhisker piezoelectric composites

Lead zirconate titanate (PZT) based piezoelectric composites embedded with ZnO nanowhiskers (ZnO_w) were investigated to clarify the optimal sintering condition for densification, microstructure, and electrical properties. The samples are characterized by X-ray diffraction analysis and scanning electron microscopy. The results show that the increase of the sintering temperature and time is quite effective in improving the densification and piezoelectric properties of the PZT/ZnO_w composites. However, the relative density and piezoelectric properties deteriorate as the composites are sintered over the optimal sintering condition. Particularly, the PZT/ZnO_w composites sintered at 1150 °C for 2 h show excellent electrical properties of piezoelectric constant d₃₃ ∼ 471 pC/N, relative dielectric constant ε ∼ 3838, planar electromechanical coupling factor k_p ∼ 0.543, remnant polarization P_r ∼ 23.2 μC/cm² and coercive field E_c ∼ 9.2 kV/cm.