Effects of B2O3-Bi2O3 addition on the dielectric properties of low-temperature-sintered MgO-TiO2(w) ceramics

The effects of different contents of B2O3-Bi2O3 on the sintering temperature and dielectric properties of MgO-12%TiO2(w) ceramics were investigated. B2O3-Bi2O3 addition effectively reduced the sintering temperature and improved the dielectric properties of ceramic samples; however, an excessive amount of B2O3-Bi2O3 led to the deterioration of dielectric properties. This is because Bi2O3 participated in the chemical reaction between MgO and TiO2 and generated a high-dielectric-loss Bi2Ti2O7 phase, resulting in an increased dielectric loss in the ceramic samples. In contrast, B2O3 formed a liquid phase to fill the grain gaps and pores during sintering, improving the densities of the ceramic samples. An appropriate amount of B2O3-Bi2O3 accelerated the reaction between MgO and TiO2 and formed ultralow-dielectric-loss phases—MgTiO3 and Mg2TiO4, and the dielectric losses of the ceramic samples decreased to an order of 10−5.