Potassium doping of semiconducting vanadium tellurate glasses

Glasses of the ternary system 2TeO2xK2O(1−x)V2O5 have been prepared for x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 mol%. For each composition only one glass transition Tg is observed in the temperature range 497–517 K. For each composition, the conductivity data were obtained in the temperature range 323–473 K, using impedance techniques. They obey an Arrhenius relationship with a composition independent pre-exponential factor. The isothermal conductivity curves exhibit a sharp minimum near x=0.5. The experimental data suggest that a polaron hopping mechanism operates in the electronically conducting domain of 0≤x<5 and an interstitial pair mechanism operates in the ionically conducting domain of 0.5