The electrical conductivity of pure and binary TeO 2 glasses

Abstract

Impedance spectroscopy has been used to measure the electrical conductivity of a TeO2 glass with a purity exceeding 98.5 mol%. This data is compared with the conductivity of the binary tellurite glass of composition 67%TeO2+33%WO3. These first determinations of the electrical conductivity of tellurite glasses indicate the nature of electrical conduction mechanisms in such materials. A sharp break in the slope of the log conductivity with reciprocal temperature divides the conductivity data in these tellurite glasses into two distinct temperature regimes; the conductivity mechanisms at low temperatures has a much lower activation energy than that at higher temperatures. The conductivity data are consistent with the charge carrier being a small polaron. The conductivities have been analyzed using small polaron theory to establish the thermal, disorder and activation energies for the carriers in both glasses. Throughout the whole range of temperature (90–430 K) of study the conductivity of the binary glass is several times larger than that of the parent glass. Calculated activation energies are consistently smaller for the binary glass than for the parent vitreous TeO2: addition of WO3 results in the phonon-assisted hopping processes having substantially smaller barriers to surmount.