Study on the reduction of uranium and color centers in U:CaF2 single crystals grown by the temperature gradient technique

Abstract: Thermoluminescence and additional absorption spectra were investigated to study color centers and valence changing of uranium in as-grown and irradiated U3+:CaF2 crystals. Glow curve of the former has only peak, while the latter has two. The trap parameters associated with individual peaks were estimated by both peak profile and curve fitting methods. A model was established to explain the U4+ reduction mechanism. Based on the model, two kinds of complexes of were tentatively supposed to be present in the as-grown U3+:CaF2. All the processes during fast heating and γ-irradiation were also illuminated. [Copyright &y& Elsevier]