Piezoelectric and dielectric properties of Fe₂O₃-doped 0.57Pb(Sc_1/2Nb_1/2)O₃-0.43PbTiO₃ ceramic materials

High-power piezoelectric materials are presently being extensively developed for applications such as ultrasonic motors and piezoelectric transformers. In this study, the piezoelectric and dielectric properties of Fe₂O₃-doped 0.57Pb(Sc_1/2Nb_1/2)O₃-0.43PbTiO₃ (hereafter 0.57PSN-0.43PT), which is the morphotropic phase boundary composition of the PSN-PT system, were investigated. The maximum dielectric constant (ε₃₃/ε₀ = 2551) and the minimum dielectric loss (tanδ = 0.51%) at room temperature were obtained at Fe₂O₃ additions of 0.1 wt% and 0.3 wt%, respectively. The temperature dependence of the dielectric constant and the dielectric loss was measured between room temperature and 350°C. With the addition of Fe₂O₃, the piezoelectric constant d₃₃ and electromechanical coupling factor k_p were slightly decreased, but the mechanical quality factor Q_m was significantly increased. The highest mechanical quality factor (Q_m = 297) was obtained at 0.3 wt% Fe₂O₃, which is 4.4 times higher than that of nondoped 0.57PSN-0.43PT ceramics. The P-E and S-E loops of the samples at room temperature and at 1.0 Hz were measured at the same time using an automated polarization measuring system.