Improvement of the Radiation Resistance of YAG:Pr and GSAG:Pr Garnets by Li+ Co-doping

The radiation resistance of YAG:Pr and GSAG:Pr garnets with Li + and Ca 2+ codoping grown by the Bridgman method is studied. The values of γ-ray induced absorption coefficient, μ(ind), are calculated at 323 nm, close to the emission maximum of YAG:Pr. After 1 kGy dose, the μ(ind) value in YAG:Pr with optimal Pr 3+ content (0.2-0.3 at%) is more than 40 m -1 , while introduction of Li + leads to a decrease of μ(ind) to less than 20 m -1 . A more remarkable effect is seen in GSAG:Pr,Li with μ(ind) close to zero after both 1 and 10 kGy doses. The parameter μ(ind) is found to correlate with color centers in as-grown crystals below 300 nm. Li + -codoping in the two studied garnets is seen efficient to control oxygen vacancies and thus formation under irradiation of related defects absorbing in the range of emission. Discussion of the mechanisms is based on the behavior of crystals with Li + , as well as in comparison to Ca 2+ co-doping.