Electret properties of silicon dioxide aerogels

In this paper, the electret properties of a kind of new inorganic materials, the silicon dioxide aerogels, are studied. By using single- and two- step sol-gel processing and supercritical drying method, bulk and film silicon dioxide aerogels of low density which is about several hundred mg/cm³ are prepared. Samples are heat treated at 800°C for several hours to eliminate organic residuals and water and then chemical surface modified by hexamethyldisilazane treatment. Electret properties of these samples corona charged at temperatures ranging from RT to 200°C are studied with measurements of isothermal surface potential decay as well as thermally stimulated discharge. The relationship between the microstructure of these samples and their electret properties is discussed. Our results show that silicon dioxide aerogels with rather good electret properties are obtained