X8R型BaTiO3基细晶陶瓷的制备、结构和性能

由于在-55~150 ℃存在正交-四方和四方-立方相变,相变对应的尖锐介电峰使BaTiO₃陶瓷介电性能难以满足X8R温度稳定性要求。本文采用50 nm的纳米BaTiO₃粉体和少量堇青石(MgO-Al₂O₃-SiO₂, MAS)玻璃,制备了满足X8R介电温度特性的BaTiO₃基细晶陶瓷。结果表明,随着MAS玻璃的加入,BaTiO₃基陶瓷的室温晶体结构从四方相转变成赝立方相,平均晶粒尺寸从纯BaTiO₃陶瓷的1.904 μm显著降低到添加0.5%(质量分数)MAS玻璃的BaTiO₃基陶瓷的183 nm。与此同时,BaTiO₃基陶瓷虽然介电常数有所下降,但是介电损耗和介电性能的温度稳定性大幅度改善。其中添加0.5%MAS玻璃的BaTiO₃基细晶陶瓷介电性能为:在1 kHz时室温介电常数为984,介电损耗为0.006 5,满足X8R温度特性要求。

Preparation,Structure and Properties of X8R BaTiO3 Based Fine-Grained Ceramics

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.