Color centers in neutron-irradiated Y3Al5O12, CAF2 and LiF single crystals

Li colloids formation study induced by reactor neutrons in LiF single crystals

“…Thermal transformation of F-type centers into colloids at higher temperature confirming our previous results [19]. The same observation has already been made in other alkali halide crystals [30,31].…”

“…The photoluminescence excited from 445 nm optical absorption band shows two emission bands with maxima at 570 nm and 660 nm due to the luminescence of F þ 3 and F 2 centers, respectively. With increasing annealing temperature up to 350°C, the absorption intensity increases and broadens (extended from 430 to 500 nm) as discussed in our previous work [19]; whereas, photoluminescence intensity increases up to 250°C, then decreases with increasing annealing temperature and drastically reduced at 420°C. The sample is completely uncoloured at 480°C.…”

“…This result explains that the lithium fluoride crystallinity is progressively destroyed with reactor neutrons irradiation. May be, this explains why the sample does not recover its transparent look after annealing as mentioned in our previous work [19]. …”

“…Nevertheless, the annealing process of colour centers in irradiated-lithium fluoride is not well understood. In our previous work, the heat treatment in air of neutrons irradiated-lithium fluoride single crystals shows F centers aggregation and Li colloid formation at higher annealing temperature [19].…”

Absorption and photoluminescence study of Al2O3 single crystal irradiated with fast neutrons

“…The irradiation was performed at NUR research reactor, Algiers, at a position described in our previous work [17]. The fluence of fast neutron (E n > 1.2 MeV) was in the range of 4.4 Â 10 16 -1.4 Â 10 18 n cm À2 .…”