Microstructure and dielectric properties of LiTaO_3 ceramics with MnO_2 addition fabricated by hot-pressing sintering

摘要

Lithium tantalite (LiTaO_3) is an excellent single crystal, only a few studies focused on polycrystalline LiTaO_3 ceramics, because it is difficult to sintering densification in fabrication process by common sintering. In this paper, LiTaO_3 composite ceramics with added 3 wt% MnO_2 were obtained by hot-pressing sintering at different temperatures from 1200 to 1350 ℃. The sinterability, microstructure and dielectric properties of LiTaO_3 ceramics fabricated at sintering temperatures were investigated. The relative density of the LiTaO_3 ceramics was significantly enhanced as the sintering temperature increases first and then decreased. The LiTaO_3 ceramics achieved the highest relative density (98.6%) and shown homogeneous microstructure when sintered at 1300 ℃. The LiTaO_3 and manganese oxide phases were observed in the MnO_2/LiTaO_3 ceramics fabricated at different sintering temperatures. The dielectric properties of MnO_2/LiTaO_3 ceramics were significantly influenced by the sintering temperatures. The study of dielectric properties revealed that the specimen had excellent dielectric properties when sintering temperature was 1300 ℃ and the dielectric constant was 78, as it tends to stay invariable at room temperature.