溶胶-凝胶法制备SiO_2材料及其微波介电性能研究

Microwave dielectric properties of silica materials prepared by sol-gel method

采用溶胶-凝胶法制备了非晶SiO_2粉体,并研究了不同溶液配比对所得粉体粒度和分散性的影响。结果表明:当H2O和TEOS摩尔比为20:1和40:1时,可以制备出分散性较好的非晶SiO_2粉体,其粒度分别为700 nm和120 nm。在此基础上,研究了不同原料粉体对SiO_2材料烧结特性和微波介电性能的影响规律。研究发现:粉体粒度较小,有利于降低SiO_2材料的烧结温度,提高其相对密度,抑制其析晶现象。当烧结温度为1050~1200℃时,SiO_2材料的相对介电常数为2.50~3.75,Q·f值为9850~61 272 GHz,τf值的变化范围为±15×10–6/℃(温度范围为25~85℃),适合用于制作微波介质基板。

Amorphous silica powders were prepared by sol-gel method, and the effects of solution concentrations on the particle sizes and dispersibilities of powders were studied. The results show that, when the mole ratio of H2O to TEOS is 20：1 and 40：1, the prepared amorphous silica powders have good dispersibility, and their particle sizes were 700 nm and 120 nm, respectively. Furthermore, the effect of different raw powders on the sintering characteristics and microwave dielectric properties of silica materials were investigated. The results show that, the finer particle size could decrease the sintering temperatures of silica materials, increase relative densities of silica materials, and inhibit the formation of cristobalite. When the sintering temperature is between 1050 ℃ and 1200 ℃, the dielectric constants, Q·f values and τf values of silica materials were 2.50-3.75, 9850-61272 GHz and ±15×10^–6/℃, respectively, which is suitable for the production of microwave dielectric substrates.