Temperature stable dielectric properties of lead-free BiFeO₃–BaTiO₃ modified with LiTaO₃ ceramics

LiTaO₃ (LT)-modified (1 − x)(0.675BiFeO₃–0.325BaTiO₃) + 0.6 mol% MnO₂ + 0.4 mol% CuO (BFBTMC–xLT, where x = 0–0.030) ceramics were synthesized by solid state reaction method. The crystal symmetry, ferroelectric response, and temperature stable dielectric properties were investigated as a function of different LT-content. The X-ray diffraction study of BFBTMC–LT piezoceramics revealed no remarkable variation in the crystal symmetry. The value of maximum polarization (P_m ≈ 24 μC/cm²) and remnant polarization (P_r ≈ 18 μC/cm²) were obtained at BFBTMC–0.010LT composition. The maximum temperature of permittivity (T_max) decreased by the addition of LT-content in BFBTMC materials. The un-doped sample was ferroelectric; a change to relaxor behavior occurred by the addition of LT-content, with broad frequency dependent curves of dielectric mid-value permittivity (ε_rmid) and tangent loss as a function of temperature. A significant enhancement occurred at 3 mol% LT-modified BFBTMC ceramics, with ε_rmid = 5000 ± 9.5% (250–450 °C at 1 kHz). These results are favorable for practical applications in high temperature dielectrics.