An investigation of the stability of interstitials produced by room temperature irradiation in KC1

Thermal stability of interstitials following room temperature irradiation has been investigated in KC1 : Harshaw, KC1 : Zone Refined, KC1 : Li, KC1 : Na and KC1 : Ag. This has been monitored via the annealing of their complementary defects, namely, the F-centres. Attention was paid to the atomic size effects of monovalent cation impurities in cation sublattice. Isochronal annealing curves showed that in crystals doped with impurities of small atomic sizes compared to potassium atoms (Li- and Na-doped samples), F-centres annealed out at higher temperatures (similar to 570K and similar to 540K respectively) compared to standard crystals (similar to 500K). Samples doped with large-sized impurities (Ag-doped samples) annealed out at lower temperatures (similar to 380K) compared to standard samples (similar to 500K). It has thus been concluded that the thermal stability of interstitials depends on the atomic size of the impurity trap and increases as the atomic size decreases. Activation energy spectra indicated that in KC1 : Ag, band I (associated with impurities) occurred around 1,28 eV and 1,35 eV, while in KC1 : Na and KC1 : Li, band III (associated with impurities) was peaking at 1,55 eV and 1,57 eV respectively. This shows a shift towards higher activation energies as the atomic size of dopant decreases