Synthesis, structural and dielectric properties of 0.8PMN–0.2PT relaxor ferroelectric ceramic

Abstract

A 0.8PMN–0.2PT solid-solution ceramic was synthesized by columbite processing technique. The effects of sintering temperature on the density, structure and microstructure and in turn on the dielectric properties were investigated. The ceramics sintered at and above 1050$^{\circ }\hbox {C}$ resulted in single-phase perovskite formation. However, high density >90% is achieved only after 1170$^{\circ }\hbox {C}$. Microstructural analysis revealed that grain size increases with increase in sintering temperature. A significant increase in the peak of dielectric permittivity only after 1150$^{\circ }\hbox {C}$ owing to increase in density is noted in this study. The quadratic law applied to this ceramic demonstrates that the transition is diffused. The broadness in phase transition and lower dielectric relaxation obtained for the composition demonstrate that the ceramic exhibits characteristics of both relaxor and normal ferroelectrics. The ceramic of composition 0.8PMN–0.2PT exhibits excellent dielectric properties $\varepsilon _{\mathrm{r}\text {-}\mathrm{max}} =$ 20294−27338 at 100 Hz with $T_{\mathrm{c}} = 100$–$96^{\circ }\hbox {C}$ at low sintering temperature 1170–1180$^{\circ }\hbox {C}$, respectively.