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

Single crystal of lithium fluoride was irradiated with neutrons at about 40 °C. The irradiation was performed with reactor neutrons at fast (E > 1 MeV) and thermal neutrons fluence of 1.8×1018cm-2 and 3.3×1018cm-2, respectively. The resulting damage was characterised by optical measurements, scanning electron microscopy and X-ray diffraction analysis. The obtained results show large Li colloids of about 0.513 μm that are formed after intense reactor neutrons irradiation. Photoluminescence spectra obtained after annealing under argon atmosphere show the F centers aggregation process with increasing annealing temperature. Li colloids intensity increases with increasing annealing temperature and shifts towards higher wavelength (500 nm).