Dielectric properties of low temperature sintered LiF doped BaFe_(0.5)Nb_(0.5)O_3

摘要

Sintering of BaFe_(0.5)Nb_(0.5)O_3:BFN requires the use of high temperatures to achieve satisfactoiy densifieation of this material. The aim of this study is to determine the effect of LiF on the sintering and electrical properties of BFN ceramics (the LiF was added as a sintering agent). The results show that LiF lowers the sintering temperature by 150-200 deg C without affecting the formation of BFN. Ceramics doped with 2-3 percent LiF show optimum densities of about 93-94 percent of the theoretical value when sintered at low temperatures (1000-1100 deg C). Samples containing 2-3 percent LiF show the following dielectric behaviour. The dielectric constant curves are very broad over a wide temperature range, with room-temperature values of 7154 in the 2 percent LiF sample and 2527 in the 3 percent LiF sample. The dielectric constants gradually increase up to 300 deg C to values of about 38,862 in the 2 percent LiF sample and 40,471 in the 3 percent LiF sample. Furthermore, the addition of 2-3 percent LiF to BFN causes a reduction in the room-temperature dielectric loss from 4.29 in undoped BFN to less than 1.2 for LiF-containing samples.