Radiation induced colour centres in cerium fluoride

Abstract

Radiation induced colour centres in CeF3 crystals have been studied by spectroscopic techniques using eight crystals produced with various degrees of purity by different manufacturers in slightly different growing conditions. The crystals were irradiated at liquid nitrogen temperature with electrons of 7 MeV at doses of lo4 to 3. lo6 rad. Absorption spectra ranging between 250 and 750 nm recorded at irradiation temperature are quite different from one producer to another, regarding both the values of absorption coefficient (17 cm-' -5 cm-') and the number and form of the absorption bands.Step-by-step annealing up to room temperature produces new absorption bands. In the range of 200-240 K, three well resolved bands appear as in the case of crystals irradiated at room temperature.