X-ray induced optical absorption in Li2B4O7 and Li2B4O7:Cu single crystals and glasses

The effect of X-ray irradiation of doses up to 2000 Gy on the spectral dependence of optical absorption (OA) has been investigated for single-crystal and glassy Li2B4O7 (LTB) and Li2B4O7:Cu (LTB:Cu). The irradiation of LTB:Cu single crystals leads to an increase of the OA intensity of the impurity bands and to formation of the induced OA band in the 3.3-4.3 eV range, whose spectral maximum shifts towards the lower-energy region with the dose increase. The irradiation of glassy LTB and LTB:Cu results in an increase of OA and, for LTB:Cu, in a shift of its short-wave edge towards the lower-energy region.