Polaronic transport in iron-vanadate glassy semiconductors

Measurements are reported of the electrical conductivity of iron vanadate glassy semiconductors over the temperature range 80-450 K. The data is analysed in the light of existing theoretical models of polaronic hopping conductions. The high-temperature behaviour is consistent with phonon-assisted hopping of polarons in the adiabatic regime. Variable-range hopping accounts for the temperature dependence of the electrical conductivity at lower temperatures. Application of the polaronic model to the experimental data provides reasonable values of the polaron radius, the wavefunction localization length and denstiy of states at the Fermi level