Electrical conduction in paratellurite (TeO2) crystals

Electrical conduction measurements on TeO2 single crystals are made both for orientations parallel and perpendicular to the tetragonal symmetry axis. Below approximately 400 0C, a single Arrhenius plot is obtained in each orientation, with activation energies Esub(parallel) = 0.54 and Esub(perpendicular) = 0.42 eV. It is concluded that conductivity in this range is ionic, falling into the extrinsic dissociation range of behaviour. Possibly, oxygen-ion vacancies are responsible. At high temperature the conductivity increases sharply due to reduction of the sample and the onset of electronic carriers. (author)