掺硅钛酸钡纳米粉体及其陶瓷的制备和表征

Preparation and characterization of Si-doped BaTiO_3 nanosized powders and ceramics

目的制备均匀的掺硅BaTiO_3纳米粉体及其高介电常数和高介电温度稳定性的钛酸钡基陶瓷。方法采用溶胶-凝胶(sol-gel)法制备掺硅钛酸钡基纳米粉体及其陶瓷样品,通过XRD,TEM和SEM对它们进行表征,并测试陶瓷的介电性能。结果采用sol-gel制得纳米级(～50 nm)掺硅BaTiO_3粉体,主要相组成为立方相,当掺硅摩尔分数增加到0.10时,有Ba_2TiSi_2O_8新相生成;烧结后的掺硅钛酸钡陶瓷主要相组成为四方结构;当掺硅摩尔分数为0.003,陶瓷的室温介电常数为4 081,介电损耗为0.004,而且ε-TT曲线比较平坦,介电温度稳定性较好。结论采用sol-gel可制得掺硅的钛酸钡纳米粉体和具有高介电常数和高介电温度稳定性的钛酸钡基陶瓷,温度稳定性满足Z5U(E)特性。

Aim In order to synthesize homogeneously Si-doped BaTiO3 powders and the BaTiO3-based fine-grained ceramics with high dielectric constant and outstanding dielectric temperature stability. Methods The Si-doped BaTiO3 powders and ceramics were prepared by a sol-gel process. The powders and ceramics were characterized by methods of XRD, SEM and TEM. The effects of Si concentration on the microstructures and dielectric properties of the ceramics were studied. Results The powders were all cubic BaTiO3 phase with Si concentration ≤0.05 with nanometer scale （ -50 nm）. When increasing the Si doping content to 0. 10, a new phase of Ba2TiSi2O8 appeared. After sintering, the cubic BaTiO3 phase was transformed into tetrahedron BaTiO3 phase. Si doping with low concentration resulted in improving grain growth and reduced dielectric loss whilst decreasing the sintering temperature. The BaTiO3 ceramics with 0. 003 Si-doped had the maximum room temperature permittivity （4081） and the minimum dielectric loss （0. 004）. The cures of 6-T is relatively fiat and dielectric temperature stability is preferable. Conclusion The Si-doped BaTiO3 nanosized powders and the ceramics with high dielectric constant and outstanding dielectric temperature stability which meets Z5U （E） characteristic can be prepared via the sol-gel process.