Classical hopping in sol-gel cobalt silicate glass

The complex AC conductivity of the sol-gel-derived cobalt silicate gel-glasses is reported for the frequency range 10(2)-10(5) Hz and temperature range 80-300 K. The experimental results were analysed in terms of theoretical models based on quantum tunnelling and classical hopping theories. It has been observed that classical hopping theory is the best model to explain the results for these glasses and that not all sites participate in the AC hopping mechanism.