Effects of atmospheric powder on microstructure and piezoelectric properties of PMZN-PZT quaternary ceramics

The effects of atmospheric powder on microstructure and piezoelectric properties of Pb(Mn_1/3Nb_2/3)O₃–Pb(Zn_1/3Nb_2/3)O₃–PbZrO₃–PbTiO₃ (PMZN-PZT) quaternary ceramics were investigated. Specimens with various contents of Pb(Mn_1/3Nb_2/3)O₃ from 0 to 20 mol% were prepared by columbite two-stage process with and without atmospheric powder of PbZrO₃. The results revealed that the atmospheric powder is favored to the liquid-state sintering process in PbO vapor pressure equilibrium. The specimen sintered with atmospheric powder is homogenous and the fracture is intergranular. However, the specimen sintered without atmospheric powder is less homogenous and the fracture is essentially transgranular. On the other hand, the pyrochlore phase was formed along with the perovskite phase for the specimens sintered without atmospheric powder and the second phase was seriously detrimental to the electromechanical properties. The superior piezoelectric properties were observed for the specimens sintered with atmospheric powder. By optimizing the specimen composition, excellent piezoelectric, and dielectric properties (Q_m=2528, K_p=0.55, tan δ=0.003) were obtained at 10 mol% Pb(Mn_1/3Nb_2/3)O₃.