The high-temperature ionic conductivity of fused silica and thin films was investigated at 700 to 1400K and 570 to 830K, respectively, by means of impedance spectroscopy. The results were consistent with the existence of extrinsic mechanisms, in the ionic transport of both types of oxide, due to the presence of dissociated Na ions. Numerical analysis of the experimental results led to values of 1.3 and 0.6eV for the dissociation and migration energies, respectively. No effect of H content upon alkali transport was found by comparing wet and dry samples. This was contrary to previous results for crystalline quartz.

Ionic Transport in Fused Silica and Thin Thermal SiO2 Films. D.Del Frate, S.Quilici, G.Spinolo, A.Vedda: Radiation Effects and Defects in Solids, 1999, 151[1-4], 859-62