不同SiO2含量对BaO-SrO-PbO-TiO2-Nb2O5-SiO2玻璃陶瓷介电性能的影响

Effect of Different SiO2 Content on Dielectric Properties of BaO-SrO-PbO-TiO2-SiO2-Nb2O5 Glass-Ceramic Composites

通过熔融-快冷-可控结晶技术,成功制备出同时含有铌酸盐和钛酸盐陶瓷相的BaO-SrO-PbO-TiO2-SiO2-Nb2O5纳米复合介电材料,并研究了不同SiO2含量对该玻璃陶瓷介电性能的影响。研究结果表明:800℃晶化处理后,玻璃基体中析出了Pb2Nb2O7,(Ba,Sr,Pb)Nb2O6和(Sr,Pb)TiO3 3种晶相;随着结晶温度升高,烧绿石结构的Pb2Nb2O7相消失,在900℃和1000℃结晶处理的样品中,只析出(Ba,Sr,Pb)Nb2O6和(Sr,Pb)TiO3两种晶相。另外, SiO2含量的调整没有改变不同结晶温度下的析出陶瓷相种类。微观结构分析结果显示随着晶化温度的增加,晶粒尺寸在不断长大, 1000℃晶化处理后的晶粒尺寸增加非常明显,最大达到500 nm左右。通过对SiO2玻璃相含量的调整获得了两种介电性能优异的玻璃陶瓷成分,在高介电常数方面, 2.5BaO-18.5SrO-8.5PbO-8TiO2-16SiO2-20Nb2O5玻璃陶瓷样品在1000℃结晶处理后得到1070的高介电常数,同时介电损耗维持在了0.0045的较低水平。在低介电损耗方面, 2.5BaO-18.5SrO-8.5PbO-8TiO2-20SiO2-20Nb2O5玻璃陶瓷样品在800℃晶化处理条件下实现了非常低的介电损耗,达到0.0008,介电常数保持在430,在脉冲功率技术领域展现出良好的应用前景。

BaO-SrO-PbO-TiO2-SiO2-Nb2O5 nanocomposite dielectrics containing both niobate and titanate ceramic phases were successfully prepared via melt-quenching followed by controlled crystallization. The effects of different SiO2 contents on the dielectric properties of the glass-ceramics were investigated. The results showed that the adjustment of SiO2 content did not change the type of precipitated ceramic phase. After crystallization at 800 ℃, Pb2Nb2O7,(Ba,Sr,Pb)Nb2O6 and(Sr,Pb)TiO3 phases precipitated in the glass matrix. With the crystallization temperature increased, the Pb2Nb2O7 phase with pyrochlore structure disappeared. After crystallized at 900 ℃ and 1000 ℃, there existed only(Ba,Sr,Pb)Nb2O6 and(Sr,Pb)TiO3 crystal phases. Microstructure analysis showed that with the increase of crystallization temperature, the grain size gradually increased. The size of the crystalline grains increased significantly after the crystallization at 1000 ℃ and the maximum grain size reached about 500 nm. Two kinds of glass ceramic samples with excellent dielectric properties were obtained by adjusting the SiO2 content and crystallization temperatures.In the aspect of high dielectric constant, the 2.5 BaO-18.5 SrO-8.5 PbO-8 TiO2-16 SiO2-20 Nb2O5 glass-ceramic sample obtained a high dielectric constant of 1070 and the dielectric loss of 0.0045 after crystallized at 1000 ℃. In the aspect of low dielectric loss, the 2.5 BaO-18.5 SrO-8.5 PbO-8 TiO2-20 SiO2-20 Nb2O5 glass-ceramic sample achieved a very low dielectric loss of 0.0008 and a moderate dielectric constant of 430 at the crystallization temperature of 800 ℃, and showed good prospects for the application in pulsed power field.