Effects of MnO2 addition on the structure and electrical properties of PIN-PZN-PT ceramics with MPB composition

A two-step fabrication route was used to synthesize piezoelectric ceramics 0.35Pb(In_1/2Nb_1/2)O₃-0.40Pb(Zn_1/3Nb_2/3)O₃-0.25PbTiO₃-xwt% MnO₂ (PIN-PZN-PT-xMn, x = 0.0–2.0), and the corresponding structural changes and variations in electrical parameters caused by Mn modification were also investigated. The addition of MnO₂ was quite effective to reduce the sintering temperature of PIN-PZN-PT ceramics. A pure perovskite structure was obtained in all sintered samples by XRD tests. The Curie temperature T_C, piezoelectric constant d₃₃, dielectric loss tanδ and planar electromechanical coupling coefficient k_p gradually decreased as the MnO₂ addition content increases, while the mechanical quality factor Q_m increased. The diffusive phase transition behavior became strong with increasing the MnO₂ doping content. A relatively high Q_m value on the order of 420 has been obtained at the 2 wt% MnO₂-added ceramic, which is six times higher than that of the undoped PIN-PZN-PT sample. These results indicate that Mn-doped PIN-PZN-PT ceramics show a broad prospect in the applications of electromechanical device requiring high power and high temperature.