Sm and Mn co-doped PMN-PT piezoelectric ceramics: Defect engineering strategy to achieve large d33 and high Qm

PbTiO3-based piezoelectric ceramics are key materials for developing various electromechanical transducers. For high-power ultrasonic transducers, piezoelectric ceramics are required to possess large piezoelectric coefficient (d33) and high mechanical quality factor (Qm). Although acceptor dopants can improve Qm, they also deteriorate d33. If suitable piezoelectricity-beneficial donor dopants can be introduced into acceptor-doped ceramics, it is very possible to obtain large d33 and high Qm simultaneously in donor and acceptor co-doped ceramics. In this work, a series of x mol% Sm and y mol% Mn co-doped Pb(Mg1/3Nb2/3)O3–30PbTiO3 (PMN-30PT: xSm, yMn) ceramics were prepared by the solid-phase sintered method. The crystal structure, local domain structure and electromechanical properties were systematically analyzed. Optimal performances were obtained in PMN-30PT: 2.5Sm, 1–2Mn ceramics with d33=860–543 pC/N, Qm=495–754, and dielectric loss tanδ=0.0055–0.0086. This high performance originates from the combined effects of (MnTi″−Vo••)× defect dipoles and the local structural heterogeneity.