Low temperature sintering and dielectric properties of (Ba,Ca)(Ti,Li)(O,F)3 ceramics with high permittivity

Cold-pressed pellets were prepared from a powder mixture of BaTiO3 with 5 mol% of (CaF2 + LiF). The pellets were then air-fired at different temperatures (800, 930, 1000 or 1100 °C) for different times (2, 4 or 8 h). Dielectric measurements were conducted at temperatures in the range 100–450 K with a wide frequency range, 100 Hz–40 MHz. Permittivity, εr′, showed a diffuse ferroelectric–paraelectric phase transition at lower temperatures (263 K⩽TC⩽368 K263 K⩽TC⩽368 K), where TCTC is the Curie temperature. In agreement with a non-relaxor ferroelectric behavior, the ferroelectric Curie temperature was frequency-independent. Dielectric dispersion was significant beyond ∼10 MHz. Ceramics sintered between 930 and 1100 °C are promising candidates for future fabrication of class II capacitors.

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