High power piezoelectric transformers with Pb(Mg_1/3Nb _2/3)O₃-PbTiO₃ single crystals

Plate-shaped piezoelectric transformers were designed and manufactured with Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ single crystals (PMN-PT). Theoretical analysis was performed using Mason's equivalent circuit model and finite element method (FEM) simulations. In the experiment, transformer performances, especially the power density, were compared among different materials, including lead zirconate titanate (PZT) ceramics, undoped PMN-PT, and manganese-doped PMN-PT (Mn-PMN-PT). High power density of 38 W/cm³ was obtained using single crystals, which was 5 times that of hard PZT ceramics. The power level of the single crystal transformer showed a significant dependence on doping, poling direction, and cutting orientation. Results also verified that the high power performance was mainly determined by the electromechanical coupling coefficient and mechanical quality factor of the material.