Electrical conduction and dielectric relaxation in vanadium phosphate glasses

Abstract

Electrical conduction and dielectric relaxation in (V 2O 5) 1 − x (P 2O 5) x glasses (where x = 0.12, 0.18 and 0.24) have been investigated in the temperature range 300–560 K and frequency range 50 Hz-10 kHz. The temperature dependences of both bulk and d.c. conductivities are described by the Mott and Davis equation for conduction in amorphous solids with activation energies of 0.0355–0.0546 eV and 0.4–0.47 eV, respectively. The results of d.c. conductivity are discussed on the basis of small polaron hopping between V 4+ and V 5+ sites beyond θ D/2, whereas the results of bulk conductivity are discussed according to the electron hopping between filled and empty localized states at the Fermi level. The a.c. conductivity is found to obey the power relation σ = Aω n . Reasonable values of both hopping rate and relaxation time are obtained and discussed. The results of conduction as well as dielectric properties are discussed on the basis of both bulk and domain interfaces, which play a significant role in both conduction and relaxation processes in the glass matrix.