Ionic and Gamma-ray Induced Photoconductivity of MgO

Abstract

The d.c. electrical conductivity of MgO has been measured, both in the presence and in the absence of an intense γ-ray field, in the temperature range 300 to 600 K. Outside the radiation environment, the conductivity is attributed to the migration of positive ion vacancies, with an activation energy of 1.50 eV. The magnitude of the conductivity is much larger than would be expected from the normal vacancy concentration and this is explained by extra magnesium vacancies acting as charge compensators for trivalent transition metal ion impurities. In the γ-ray radiation field of a 60Co source the observed photoconductivity is described by a trapping model, with levels at 0.04,0.55, and 1.35 eV below the conduction band. The γ-ray induced conductivity is consistent with a linear dependence on the radiation dose rate up to 4.0 × 105 rad/h(H2O).