Ionic conductivity and stored energy in gamma-irradiated NaF

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 degrees C, which is the range in which the main stored-energy release peak occurs. The energy released below 600 degrees C, when the irradiated sample is heated, is 1.9 x 10(20) 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.