Dielectric behavior and percolation phenomena in porous silica gels

The purpose of the present Letter is the use of dielectric relaxation for i nvestigating percolation phenomena in sol-gel glasses with different cataly sts. The broadband dielectric spectroscopy method was employed to investiga te glasses of fine porosity produced via the sol-gel route with different c atalysts. The study was carried out in the frequency range of 20 Hz to 1 MH z and temperature interval - 100 degrees C to + 150 degrees C. The dielectr ic response data were analyzed both in frequency and time domains and then interpreted in terms of the various non-Debye relaxation processes. The mec hanisms of the processes are discussed. One of them is associated with perc olation of electric excitation along the developed fractal structure of con nected pores. (C) 2000 Elsevier Science B.V. All rights reserved.