Ferroelectric, electromechanical, and dielectric properties of (Na _0.5Bi_0.5)_0.94Ba_0.06TiO₃ co-doped MnO₂ and La₂O₃ lead-free ceramics

The modified (Na_0.5Bi_0.5)_0.94Ba _0.03La_0.02Ti_0.995Mn_0.005O ₃ lead-free ceramics were prepared using a traditional solid-state reaction process, and their structures were characterized by X-ray diffraction, scanning electron microscope, and Raman spectroscopy, respectively. A double-like P-E loop was discussed at the room temperature for the co-doped ceramics by reason of the appearance of the anti-ferroelectric. The ferroelectric hysteresis loop and field-induced strain were studied at different temperatures. A large strain (S₃₃ = 0.33 %, E = 50 kV/cm at 120 C) was observed due to the transformation between ferroelectric and anti-ferroelectric phase at the phase transition temperature. Also, the depolarization temperature (T_d) of the co-doped ceramics was determined from the pyroelectric current density versus temperature plots, which was consistent with the result from the position of dielectric loss's peak as a function of temperature.