关键词: BaTiO₃, X8R, 介电性能, 细晶, MAS玻璃, 介电损耗

Abstract: Due to the orthogonal-tetragonal and tetragonal-cubic phase transitions of BaTiO₃ in the range of -55 ℃ to 150 ℃, the sharp dielectric peaks corresponding to these phase transitions make the dielectric properties of BaTiO₃ ceramics difficult to meet the temperature stability requirements of X8R. In this paper, the BaTiO₃ based fine-grained ceramics were prepared by using 50 nm nano-BaTiO₃ powder and a small amount of cordierite (MgO-Al₂O₃-SiO₂, MAS) glass to meet the dielectric temperature specification of X8R. The results indicate that the crystal structure of BaTiO₃ based ceramics at room temperature changes from tetragonal phase to pseudo-cubic phase with the addition of MAS glass. The average grain size decreases significantly from 1.904 μm for pure BaTiO₃ ceramics to 183 nm for BaTiO₃ based ceramics with 0.5% (mass fraction) MAS glass. Meantime, although the dielectric constant of BaTiO₃ based ceramics decreases, the dielectric loss and temperature stability of dielectric properties are greatly improved. When the MAS glass content is 0.5%, the dielectric properties of BaTiO₃ based fine-grained ceramics are as follows: the dielectric constant of 984 and dielectric loss of 0.006 5 at 1 kHz and room temperature, meeting the temperature specification requirements of X8R.

Key words: BaTiO₃, X8R, dielectric property, fine grain, MAS glass, dielectric loss