Growth and characterization of novel piezo-/ferroelectric single crystals from the PSN-BS-PT ternary system

Bismuth-based single crystals with the nominal composition of 0.1Pb(Sc_1/2Nb_1/2)O₃-0.315BiScO₃-0.585PbTiO₃ (0.1PSN-0.315BS-0.585PT) ternary complex perovskite system were successfully grown using a high-temperature solution growth (HTSG) method. A mixture of PbO and Bi₂O₃ in a molar ratio of 73:27 was used as flux, and the flux to charge ratio was optimized to be 70:30 (wt%). The grown crystals, with dimensions up to 3 mm, exhibit a pseudo-cubic morphology. The XRD patterns of the ground powder and naturally formed pseudo-cubic facets confirm that the grown single crystals crystallize in the perovskite structure with the rhombohedral symmetry as the major phase, and the naturally grown pseudo-cubic facets are parallel to {1 0 0}_C. The domain structures in the (0 0 1)-oriented single crystals examined by polarized light microscopy (PLM) and optical crystallography reveal the coexistence of rhombohedral and monoclinic phases in majority, with the presence of a minor tetragonal phase likely grown at the late stage of the growth, demonstrating the morphotropic phase boundary (MPB) characteristics for the grown crystals. Upon heating, phase transition from the major rhombohedral and monoclinic to the cubic phase take place at T_C = 370 °C. The ferroelectric properties are displayed by polarization-electric field (P-E) hysteresis loops with a remanent polarization of 17 µC/cm² and a high coercive field of 68 kV/cm. The piezoelectric coefficient (d₃₃) is found to be 478 pC/N. The high Curie temperature and decent piezo- and ferroelectric performance of the PSN-BS-PT crystals make this ternary complex perovskite system a promising candidate for potential applications in high-temperature and high-power electromechanical transduction.