Effect of ZnO addition on the sintering and electrical properties of (Mn,W)-doped PZT-PMS-PZN ceramics

The effect of ZnO addition on the phase structure, microstructure and dielectric and piezoelectric properties of 0.2 wt.% MnO₂ and 0.6 wt.% WO₃-doped Pb(Zr_0.52Ti_0.48)O₃-Pb(Mn_1/3Sb_2/3)O₃-Pb(Zn_1/3Nb_2/3)O₃ (PZT-PMS-PZN) ceramics was investigated. X-ray diffraction shows that the phase structure of ceramics is transformed from rhombohedral to tetragonal with the increasing of ZnO addition. The bulk density significantly increases when ZnO is added and then it slightly decreases for ZnO addition above 0.2 wt.%. SEM micrographs show the grains of ceramics are uniform and well developed by adding 0.1 wt.% ZnO. The Curie temperature (T_c) of 270 °C is obtained at the 0.1 wt.% ZnO addition. Mechanical quality factor (Q_m), electromechanical coupling factor (K_p) and piezoelectric constant (d₃₃) increase firstly, and then decrease with the increasing of ZnO addition, while dielectric loss tan δ drops all the time. The Q_m, K_p, d₃₃, tan δ and T_c of the ceramics show the optimum values of 1899, 0.55, 300 (pC/N), 0.0063 and 270 °C, respectively, at the lower sintering temperature of 1120 °C and with 0.1 wt.% ZnO addition.