Double hysteresis loops and enhanced mechanical quality factor of Mn-doped 0.75PMN-0.25PT ceramics

Relaxor ferroelectric 0.75 Pb(Mg1/3Nb2/3)O-3-0.25PbTiO(3) (0.75PMN-0.25PT) ceramics with Mn-doping concentration of 0%, 1%, 2% and 3 mol% were prepared by two-step sintering. The phase composition, microstructure, dielectric property, ferroelectric property, piezoelectric property and electromechanical property were investigated. Results indicate that all ceramics exhibit pure perovskite phases and high density. Mn-doping induces some decrease in dielectric constant epsilon(r), dielectric loss tan delta, remnant polarization P-r, piezoelectric coefficient d(33), and electromechanical coupling coefficient k(p), while significant increase in mechanical quality factor Q(m) and the figure of merit (FOM) of 0.75PMN-0.25PT ceramics. For 3 mol% Mn-doped 0.75PMN-0.25PT ceramics, Q(m) enhances by 1449%, FOM increases by 923%, and tand decreases by 67%, which makes it more suitable for high power applications. Interestingly, double P-E loops are observed in 3 mol% Mn-doped 0.75PMN-0.25PT ceramics. The phenomenon was investigated by the symmetry-conforming principle of point defects and the internal bias field.