Phase diagram and properties of Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ polycrystalline ceramics

yPb(In_1/2Nb_1/2)O₃-(1-x-y)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ (yPIN-(1-x-y)PMN-xPT) polycrystalline ceramics with morphotropic phase boundary (MPB) compositions were synthesized using columbite precursor method. X-ray diffraction results indicated that the MPB of PIN-PMN-PT was located around PT=0.33-0.36, confirmed by their respective dielectric, piezoelectric and electromechanical properties. The optimum properties were found for the MPB composition 0.36PIN-0.30PMN-0.34PT, with dielectric permittivity e{open}_r of 2970, piezoelectric coefficient d₃₃ of 450pC/N, planar electromechanical coupling k_p of 49%, remanent polarization P_r of 31.6μC/cm² and T_C of 245°C. According to the results of dielectric and pyroelectric measurements, the Curie temperature T_C and rhombohedral to tetragonal phase transition temperature T_R-T were obtained, and the "flat" MPB for PIN-PMN-PT was achieved, indicating that the strongly curved MPB in PMN-PT system was improved by adding PIN component, offering the possibility to grow single crystals with high electromechanical properties and expanded temperature usage range (limited by T_R-T).