Dielectric and piezoelectric properties of manganese-modified PbHfO₃-PbTiO₃-Pb(Mg_1/3Nb_2/3)O₃ ternary ceramics with morphotropic phase boundary compositions

High piezoelectric and electromechanical properties were reported in the PbHfO₃-PbTiO₃-Pb(Mg_1/3Nb_2/3)O₃ ternary system with morphotropic phase boundary (MPB) compositions. This work focuses on the effect of MnO₂ addition on 0.8Pb(Hf_0.443Ti_0.557)O₃-0.2PMN (0.8PHT-0.2PMN) ceramics. It was observed that the Mn acceptor modification induced a "hardening" effect in 0.8PHT-0.2PMN, with decreased piezoelectric coefficients d₃₃ and dielectric loss tan δ and a significantly increased mechanical quality factor Q_m. Moreover, the 0.2 wt% MnO₂-doped 0.8PHT-0.2PMN ceramics exhibited good piezoelectric and electromechanical properties with d₃₃, planar electromechanical coupling k_p and Q_m being on the order of 360 pC/N, 61% and 700, respectively, showing advantages compared to those of commercial hard PZT4 ceramics, which is attractive for high power applications.