中文摘要：

用蔗糖、SiO2、Al2O3溶胶，利用碳热还原法合成了碳化硅粉体。研究结果表明，在1450℃；有少量碳化硅合成。随着合成温度的提高，合成产物逐步由非晶态转化碳化硅：随着合成产物中碳化硅含量的升高，合成粉末的复介电常数增大。与合成的纯碳化硅相比，添加少量Al2O3溶胶后合成的碳化硅的复介电常数明显升高，其原因在于Al、O分别替代Si、C，导致SiC晶格中出现带电缺陷所致。在N2气氛中合成的碳化硅的复介电常数明显高于Ar气氛中合成的SiC的复介电常数，这是由于N原子固溶到SiC晶格中产生带电缺陷引起的。添加较多Al2O3溶胶后，合成产物的复介电常数的实部、虚部低于添加少量Al2O3溶胶时的合成产物的复介电常数的实部、虚部。分析认为，添加较多Al2O3溶胶后，合成产物中出现一定数量的Al2O3，它的复介电常数的实部、虚部均低于SiC的，从而导致合成产物的复介电常数降低。

英文摘要：

SiC powder was synthesized by carbothermal reduction method from SiO2 sol with saccharose and Al2O3 sol. The results show that a bit of SiC is formed at about 1450 ℃ and more amorphous materials turn into SiC crystal grains at higher temperatures. Both the real and imaginary parts of the permittivity of the synthesized powder rise with the temperature increasing. A little addition of Al2O3 sol into the sol of SiO2 with saccharose is helpful to increase real and imaginary parts of the permittivity of the synthesized powder. Al and O substitute Si and C respectively resulting in charged defects in SiC lattice. Compared to Ar atmosphere, higher real and imaginary parts of the permittivity of the synthesized powder were obtained in N2 atmosphere. It is believed that the charged defects from N atom substitution for C in SiC lattice lead to the increase. Compared to a little addition of Al2O3 sol, an adequate addition of Al2O3 sol to the sol of SiO2 with saccharose results in reduce in real and imaginary parts of the permittivity due to more Al2O3 formation in synthesized powder because real and imaginary parts of the permittivity of Al2O3 are lower that those of SiC.