Effect of MnO₂ addition on relaxor behavior and electrical properties of PMNST ferroelectric ceramics

Abstract A novel ferroelectric system, 0.2Pb(Mg_1/3Nb_2/3)O₃-0.8Pb(Sn_0.46Ti_0.54)O₃ with MnO₂ addition (PMNST-Mn), was prepared. The dielectric, ferroelectric and piezoelectric properties were investigated. The results demonstrated that the addition of MnO₂ suppressed the dielectric relaxor behavior of PMNST. With the increase of MnO₂ addition, the diffuse phase transition (DPT) behavior weakened gradually. The addition of MnO₂ contributed to the decrease of the dielectric loss (tanδ) and the enhancement of ferroelectric polarization. The optimum ferroelectric and piezoelectric properties were obtained when the addition of MnO₂ is 0.75 mol%, and the remnant polarization (P_r) and mechanical quality factor (Q_m) were about 25% and 60% higher than those of PMNST, respectively. It was suggested that the formation of oxygen vacancies made the important contribution to suppressing relaxor behavior and improving the electrical properties of PMNST due to the substitution of Mn for B-site. This work provided a practicable strategy to tune electrical properties of ferroelectrics.