ELECTRICAL-CONDUCTION IN GAMMA-IRRADIATED ETA-ALUMINA

Samples of eta-alumina ceramic in powder form were prepared according to the standard methods. The electrical conduction of gamma-irradiated and unirradiated alumina was studied between room temperature and 673 K. An anomalous behaviour in sigma-1/T relations is observed for all investigated samples. This behaviour is based on an attenuation in conductivity values in the relatively low temperature range followed by an activation in their values passing through minimum at characteristic temperature T{*}. The attenuation of conductivity with increasing temperature is explained according to the thermal quenching of mobile charge carriers as well as proton-phonon scattering. The activation of conductivity with increasing temperature beyond T{*} is explained on the basis of thermal activation of charge carriers from deep traps spread at energy levels between 0.44 and 0.5 eV. In addition, a remarkable increase in conductivity values is recorded with increasing gamma-radiation dose which is discussed according to the primary ionization effects of radiation.