Study On Dielectric Behavior Of BaTiO₃ Ceramics

MgTiO₃-based ceramics is a important microwave dielectric material, which has wide applications as dielectrics in resonators, filters, et al. MgTiO₃-based ceramics possesses excellent dielectric properties, additional, it is of rich in natual resource and in low price. However, MgTiO₃-based ceramics required sintering temperatures as high as 1400-1450℃, many researchers made efforts to lower the sintering temperature and improve the dielectric properties.In this thesis, MgTiO₃-CaTiO₃ ceramics are prepared by a traditional solid phase reaction. Sintering characteristic, phase transition and dielectric properties of MgTiO₃-CaTiO₃ ceramics doped with different additive have been investigated, The main results are as follows:1. The influence of dielectric properties on MgTiO₃-CaTiO₃ ceramics doped with different ionics (A: Zn²⁺, Cu²⁺, Li⁺, Co²⁺, La³⁺, Ni²⁺, V⁵⁺) were invstigated. According to charge balance principle, the defects are induced by A-site or B-site heterovalent substitute for MgTiO₃-CaTiO₃ ceramics. The results show that the instituted ionics in proper quantities can effectively lower the sintering temperature and promoted the densification, that mainly because of liquid phase appeared made crystalline grain more compact, or solid solution promote the sintering process. At the meantime, ionics substitution can also improved the dielectric properties.2. The effect of ionic substitution of A and B-site (Zn-Al, Zn-Zr, Cu-Al, Cu-Zr) for MgTiO₃-CaTiO₃ ceramics on dielectric properties are investigated. The sintering temperature of MgTiO₃-CaTiO₃ ceramics was reduced, the sintering densification was promoted and the dielectric loss was decreased. Additional, ionic substitution of A and B-site can effectively hold back the formation of the second phase MgTi₂O₅ and improved the dielectric properties.