t is
known that the changes induced in glass structure as a result of the introduction of titanium dioxide are consistent with an increase
in the number of non-bridging oxygen’s according to Villegas and
Fernandez Navarro [4] and Weng et al. studies [31], and the increase
in non-bridging oxygens resulted from the addition of Ti4+ component
which have a role as network modifier ions. Therefore, the increase
of TiO2 composition will decrease the (Eopt) because it
facilitates polaron hopping, and conductivity increases by hopping.