Chemical composition-induced evolution of the structure, domain and electrical properties of Sm-doped (1 − x)Pb(Ni1/3Nb2/3)O3–xPbTiO3

As the two typical basic binary solid solutions of the relaxor-PbTiO₃ family, Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) has been widely investigated, whereas Pb(Ni_1/3Nb_2/3)O₃-PbTiO₃ (PNN-PT) has not. Here, 1.5 mol% Sm-doped (1 − x)Pb(Ni_1/3Nb_2/3)O₃–xPbTiO₃, (1 − x)PNN–xPT:0.015Sm with x = 0.33–0.39, ceramics have been prepared and the chemical composition-induced evolution of crystal structure, domain, and electrical properties investigated systematically. With increasing PT content, evolution of the rhombohedral–tetragonal structure was observed. A rhombohedral–tetragonal morphotropic phase boundary occurred around x = 0.36–0.37, which showed a peak piezoelectric property with piezoelectric constant d₃₃ = 531 pC N⁻¹ and planar electromechanical coupling factor k_p = 0.37 at room temperature. At the same time, the x = 0.36 composition showed improved ferroelectric behavior with remanent polarization P_r = 13.4 μC cm⁻² and coercive field E_c = 3.2 kV cm⁻¹. Interestingly, different from its PMN-PT counterpart, there is no temperature-driven phase transition between room temperature and the Curie temperature for (1 − x)PNN–xPT:0.015Sm. These parameters indicated that the PNN-PT system is worthy of more attention and is a promising platform for further development of high-performance piezo/ferroelectric materials.