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 conduct ivity is not detected. The de mobilities of the polarons in vanadium p hosphate glasses are known to be almost independent of their number de nsity unless very high densities are attained. The dependence of the p olaronic transport on frequency and on number density is consistently explained by a lattice gas model which accounts for the Coulomb intera ctions between the polarons and for the structural disorder of the gla ssy network.