Study On BaTiO₃-based X8R Ceramics Sintering At Low-temperature

As one of the most important ferroelectric materials, BaTiO₃ ceramics is the ABO₃ compound with a typical perovskite structure. Due to its excellent dielectric performances and high temperature-stability, BaTiO₃-based X7R and X8R MLCC have been extensively used in the fields of mobile communication and electronic system of automobile. This paper focuses on the study of effects of additives on the process of low temperature sintering, sintering characteristics, and dielectric performances based on BaTiO₃ ceramics.Li2CO₃ and BaF2 are doped into BaTiO₃ system as additives, reacting with BaTiO₃ during the process of sintering. Low temperature reactive liquid-phase is generated in this process, and has the abilities to lower sintering temperature and reduce sintering time effectively. Then BaTiO₃ ceramics is fast-sintered at low temperature. Lattice vacancies are generated when Li⁺ substitutes the Ti⁴⁺ site of BaTiO₃. Because of its effect on accelerating the mass-tranport process, the presence of vacancies in BaTiO₃ lattice is able to decrease sintering time.The process of sintering at low temperature inhibits the abnormal grain growth of BaTiO₃ ceramics, and leads to the microstructure of fined-grain. This helps improve dielectric performances of ceramics. The sintering characteristics at low temperature is improved significantly by the addition of BaF₂ , that changes the stoichiometry of Ba/Ti, and forms a Ba-riched phase Ba₂TiO₄.By adjusting the contents of additves and considering performances parameters of ceramics comprehensively, we have finally prepared BaTiO₃-based X8R ceramics sintered at low temperature. Its main parameters were as follow:Sintering temperature: 850℃Dielectric constant:ε≥2000Dissipation factor: tgδ≤1.5%TC characteristic:Δε/ε≤±15% (-55℃ 155℃)Insulation resistivity:ρv≥1×10¹¹Î©Â·cm...