以硝酸钙、硝酸镁、正硅酸乙酯为先驱体, 利用溶胶-凝胶法合成了(Ca0.7Mg0.3)SiO3陶瓷粉体, 研究了不同物相和粒径粉体的烧结特性以及陶瓷的微波介电性能. 结果表明: 干凝胶的煅烧温度低于800℃时, 所得粉体主要为无定型态, 煅烧温度超过900℃后, 晶相大量形成; 当以无定型粉体或900℃煅烧获得的细小粒径粉体为原料时, 均难以获得致密结构的陶瓷; 形成完整的粉体原料晶相以及粒径的增大, 有利于陶瓷体的致密烧结和微波介电性能的提高. 粒径分别为50～100nm以及90～300nm的陶瓷粉体, 在1320℃烧结后均获得良好的微波介电性能, 介电常数εr分别为6.62、6.71, 品质因数Q×f值分别为36962、41842GHz, 谐振频率温度系数τf分别为--48.32×10-6/℃、--49.63×10-6/℃.
Using Ca(NO3)2·4H2O, Mg(NO3)2·6H2O and Si(OC2H 5)4 as precursors, (Ca0.7Mg0.3)SiO3 powders were prepared by sol-gel method. The crystalline phase, microstructure, sintering characteristic and microwave dielectric properties of (Ca0.7 Mg0.3)SiO3 powders calcined at different temperatures were studied. The results show that the powders calcined at 800℃ are almost amorphous and a large amount of crystalline phases are occurred when the calcination temperature increases to 900℃. The dielectric ceramics made from amorphous powders or fine powders (calcined at 900℃) can’t achieve compact structure, and the sintering characteristic and microwave dielectric properties can be enhanced by increasing the size of grains. Using (Ca0.7 Mg0. 3)SiO3 powders with grain sizes of 50--100nm and 90--300nm as raw materials, the ceramics sintered at 1320℃ possess good microwave dielectric properties: ε=6.62, Q× f=36962GHz, τf=-48.32×10-6℃-1 and ε=6.71, Q× f=41842GHz, τf=-49.63×10-6℃-1, respectively.
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