Effective A-site modulation and crystal phase evolution for high ferro/piezoelectric performance in ABO₃ compounds: Yttrium-doped BiFeO₃-BaTiO₃

Eco-friendly perovskite-structured compounds of 0.65Bi_(1-x)Y_xFeO₃-0.35BaTiO₃ (BY_xF-35BT, x = 0.00–0.03) were investigated systematically in terms of ferroelectric, piezoelectric, and dielectric properties and related crystal structure. X-ray diffraction and Rietveld refinement revealed that lattice anisotropy increased from undoped BF-35BT ceramic and transformed to a mixture of dominant tetragonal (T) and rhombohedral (R) symmetry and then pseudocubic-like structure with increasing the value of x. A remarkable enhancement was noticed in electromechanical performance for x = 0.01, having d₃₃ = 152 pC/N, and d*₃₃ = 505 pm/V at applied field of 5.5 kV/mm at room temperature (RT). The d₃₃, d*₃₃, and T_m for x = 0.01 increased to 189 pC/N at 100 °C, 904 pm/V at 3.5 kV/mm at 120 °C, and 410 °C, respectively. It is believed that enhanced piezoelectric performance is mainly attributed to reduced oxygen vacancy concentration [V_O^∙∙] and metastatic phase with high lattice anisotropy, and thereby low activation energy for domain rotation with a combinatory effect of the enhanced relative density and optimum grain size.