Dielectric response of silica aerogels

Abstract

The dielectric response of porous silica aerogel prepared hypercritical drying of gels from hydrolysis of TMOS- Methanol solution have been measured between 1.8 K to 300 K and frequencies between 50 and 105 Hz. The e value of the porous gels is found practically constant between room temperature and 100 K but smaller than that of fused silica. A sharp decrease of e' is observed near 35 K and accompanied by a large loss peak (tg delta). A small increase of e for T < 13 K is attributed to the adsorption of He atoms on the porous superficies.