Electrical properties of Al2O3 during irradiation with spallation neutrons

DC and AC conductivity of Al2O3 ceramics were measured at elevated temperatures during irradiation with neutrons and gamma rays at the Los Alamos Spallation Radiation Effects Facility. DC conductivity was increased at start of irradiation, but was subsequently reduced as displacement damage was accumulated. AC conductivity appeared to increase at high levels of damage. The observed dc behavior is attributed to excitation of electrons into the conduction band by ionizing radiation, followed by charge trapping and recombination at damage sites. The ac behavior, which resembles RIED, is attributed to conductivity in the residual gas surrounding the samples. Surface conductivity, while not the source of the apparent RIED, nevertheless is of sufficient magnitude to be of concern for fusion applications