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 (Pm ≈ 24 μC/cm2) and remnant polarization (Pr ≈ 18 μC/cm2) were obtained at BFBTMC-0.010LT composition. The maximum temperature of permittivity (Tmax) 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 (εrmid) and tangent loss as a function of temperature. A significant enhancement occurred at 3 mol% LT-modified BFBTMC ceramics, with εrmid = 5000 ± 9.5% (250-450 °C at 1 kHz). These results are favorable for practical applications in high temperature dielectrics.