Phase transitional behavior and electrical properties of Pb(In_1/2Nb_1/2)O₃–Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ ternary ceramics

Relaxor based ternary (0.60 − x)Pb(In_1/2Nb_1/2)O₃–0.40Pb(Mg_1/3Nb_2/3)–xPbTiO₃ ((0.60 − x)PIN–0.40PMN–xPT) polycrystalline ceramics were synthesized by two-step columbite precursor method. The effects of PIN/PT content on phase structure, microstructure, density, and dielectric, piezoelectric, ferroelectric and pyroelectric properties of the ternary ceramics were systematically investigated. A morphotropic phase boundary (MPB) near x = 0.34 was identified by X-ray diffraction and further confirmed by their respective electrical properties. Piezoelectric, ferroelectric and pyroelectric properties were enhanced for compositions near the MPB. The 0.26PIN–0.40PMN–0.34PT ceramics show optimum electrical properties: piezoelectric coefficient d₃₃ = 505 pC/N, planar electromechanical coupling factor k_p = 62.5 %, remnant polarization P_r = 32.1 μC/cm², coercive field E_c = 8.8 kV/cm, and room temperature pyroelectric coefficient p = 0.050 μC/cm² °C. In addition, the rhombohedral–tetragonal phase transition temperature T_rt and Curie temperature T_c of the ternary ceramics were identified by the temperature dependence of dielectric and pyroelectric measurements, which are much higher than those of binary PMN–PT ceramics, indicating the expanded temperature usage range of the ternary ceramics. The results show that this ternary system is a promising candidate for electromechanical applications with high performance and wide temperature usage range.