Densification behaviors and piezoelectric properties of MnO2, SiO2-doped Pb(Ni1/3Nb2/3)O3–PbTiO3–PbZrO3 ceramics

Abstract

The roles of additives (MnO₂, SiO₂, and CdO) in controlling microstructural development and piezoelectric properties of Pb(Ni_1/3Nb_2/3)O₃– PbTiO₃–PbZrO₃(PNN–PT–PZ) ceramics were systematically examined. The addition of SiO₂ (2 expedites the rate of grain growth without increasing the rate of densification appreciably. The observed difference in the grain-growth behavior was discussed in terms of the viscosity of liquid phase formed during sintering and the diffusion-controlled process for the solute-atoms transport. The rapid increase in the mechanical quality factor (Q_m) and the decrease in the relative dielectric permittivity (∊_r) and d₃₃ for the MnO₂-doped specimens indicate the formation of oxygen vacancies by the dissolution of Mn-atoms into the B-sites of perovskite structure. On the contrary, the presence of CdO (2 mol %) remarkably increases ∊_r and d₃₃ of PNN–PT–PZ ceramics.