Low temperature sintering properties of LiF-doped BaTiO3-based dielectric ceramics for AC MLCCs

The effects of LiF addition on phase evolution, microstructure and dielectric properties of BaTiO3 based ceramics were investigated. The LiF addition lowered the sintering temperature of BaTiO3 based ceramics effectively from 1,380 to 1,100 A degrees C. Orthorhombic-to-pseudocubic phase transition appeared as increasing sintering temperature or LiF content. Li+ dissolved in the lattice of BaTiO3, replaced Ti4+ site, produced oxygen vacancies and further inhibited the grain growth. F- entered into O2- site, might cause weakening of oxygen bond strength, together with the low-melting-point liquid phase sintering of LiF, facilitated the formation of uniform dense and fine-grained structure and maintained good dielectric properties. Samples with 2 wt% LiF sintered at 1,100 A degrees C showed excellent dielectric properties: epsilon(r) = 1,956, tan delta = 0.8 % (at 1 kHz), Delta C/C-25 < 10.44 % (-55-125 A degrees C) and alternating current breakdown voltage E > 4.50 kV/mm.