Phase transition and large strain response with ultra-low hysteresis of BaTiO₃ doped with a high-entropy perovskite oxide

(1 − x)BaTiO₃–xBi(Sc_0.2Y_0.2Al_0.2Fe_0.2Ga_0.2)O₃ (BT–BSYAFG, x = 0.02, 0.04, 0.06, 0.08, and 0.10) ceramics were successfully prepared via the solid-state reaction method. X-ray diffraction and Raman spectroscopy results reveal that a structural transition from the tetragonal (P4mm) to the pseudocubic (Pm3¯m) phase occurs with increasing x. At x = 0.04 and 0.06, the tetragonal and pseudocubic phases coexist. The relaxor behavior of the as-prepared samples is enhanced via BSYAFG doping due to the lattice distortion effect of high-entropy perovskite oxides. Additionally, the transition from the classic ferroelectric to the relaxor ferroelectric state implies that the long-range-ordered macro-domains are completely transformed into disordered polar nano-regions, which improves the strain properties. A large strain response (0.28 %) with an ultra-low hysteresis (4 %) is achieved at x = 0.06 under an electric field of 70 kV/cm. These results indicate that BT–BSYAFG ceramics are promising materials for application to the field of precision actuators.