Polaronic transport in vanadium phosphate glasses

Complete conductivity spectra have been taken of a polaron conducting glass of composition 0.8(0.89V(2)O(5) . 0.11V(2)O(4)). 0.2P(2)O(5) at various temperatures. The frequency dependent conductivity is found to display the 'universal dynamic response' behavior widely observed in disordered solid electrolytes. Contrary to some ion conducting glasses, a frequency regime with an exponent 1 < q < 2 of the hopping conductivity is not detected. The de mobilities of the polarons in vanadium phosphate glasses are known to be almost independent of their number density unless very high densities are attained. The dependence of the polaronic transport on frequency and on number density is consistently explained by a lattice gas model which accounts for the Coulomb interactions between the polarons and for the structural disorder of the glassy network.