Gamma irradiation reduces the ionic conductivity of NaF single crystals due to the decrease of the extrinsic cation-vacancy concentration. Irradiation also makes the binding energy of the impurity-cation-vacancy dipole higher than that for unirradiated samples. The thermal recovery of these effects takes place between 270 and 600°C, which is the range in which the main stored-energy release peak occurs. The energy released below 600°C, when the irradiated sample is heated, is 1.9 × 1020 eV g-1. It is proposed that these processes are related to radiation-induced divacancies, that behave as traps for the impurity-cation-vacancy dipoles.

Peer Reviewed