Sintering, microstructures and dielectric properties of Ba1−xPbx(Ti1−xLix)O3−3xF3x ferroelectric ceramics

Abstract

AbstractVarious compositions (1−x)BaTiO3 + xPbF2 + xLiF were prepared, shaped to pellets then sintered at 900°C for 2 h in gold sealed tubes. The purity and the symmetry of the obtained samples were checked by X-ray diffraction. A new solid solution with Ba1−x Pbx (Ti1−x Lix ) O3−3x F3x formula occurs in the composition range 0 ≤ x ≤ 0.20. SEM observations were performed on polished and fractured ceramics. The complex permittivity was measured as a function of temperature (−120°C ≤ T ≤ 250°C) and frequency (50 Hz ≤ f ≤ 4 × 107 Hz). The dielectric performances are the best for ceramic Ba0.97Pb0.03(Ti0.97Li0.03)O2.91F0.09. The real component ε′, exhibits a maximum of approximately 7500 at the ferroelectric Curie temperature T C ≈ -18°C, the dielectric losses tan δ value being 0.012. At room temperature, the relaxation frequency f r is around 40 MHz for this ceramic. This novel ferroelectric oxifluoride is a promising material for applications, in particular in the field of Z5U multilayer capacitors.