Mixed ionic-electronic conduction in sodium borate glasses with low V2O5content

The electrical resistivities and activation energies for electric conduction in glasses of the system Na 2 O-V 2 O 5 -B 2 O 3 with V 2 O 5 <15 mol.%, have been measured. Two types of conductivities are postulated: ionic conductivity in the higher temperature region and electronic conductivity in the lower temperature region. V 2 O 5 is assumed to be introduced into such glasses as a network former and also as a network modifier. It is deduced that the electronic conductivity in glasses with low concentrations of V 2 O 5 is strongly affected by the concentration and the structural form of V 2 O 5 in the glass. The dependence of the activation energy for electronic conduction on V 2 O 5 content, for the glasses studied, is found to differ from that for glasses with high V 2 O 5 content. It is assumed that the activation energy depends on the continuity of the V 2 O 5 network.