Effect of moisture adsorption on the broadband dielectric response of SiO2-based nanoporous glass

Atmospheric water adsorbed by porous materials may significantly change its electrodynamic response in a wide frequency range. Mechanical and chemical stabilities of silicon dioxide along with a proven manufacturing method of porous SiO2 samples made it convenient for studying the effects of moisture adsorption on various parameters of the porous media. We report the dielectric properties of SiO2-based nanoporous glass in the frequency range of 20 Hz–400 THz at ambient atmospheric conditions and at a low residual pressure of ≤1 mbar. We observed a significant low-frequency dispersion of the complex dielectric permittivity and enhancement of dielectric loss for the porous sample exposed to the ambient moisture. In the terahertz range, the change in dielectric response is smaller and correlates with the moisture saturation of the sample.