The electrical conductivity of quartz glass grades with a variety of lithium and hydroxyl contents has been determined by AC impedance spectroscopy at temperatures between 600-1100 deg C. The samples represent glass manufactured by electrical fusion and flame fusion of quartz crystals, as well as synthetic fused silica manufactured by hydrolysis of a silicon-containing precursor in an oxygen-hydrogen flame. The resulting plots of conductivity versus temperature yielded good Arrhenius dependencies enabling determination fo the activation energies for electrical conduction. The activation energies showed a change in magnitude at about 800 deg C. Complementing data from previous studies, the results show that the conductivity is determined primarily by the lithium content in the natural fused quartz grades. In the synthetic fused silica materials, the hydroxyl content plays the predominant role.
