Optical Absorption of Irradiated Glass-Like Lithium Tetraborate Li2B4O7, Doped with Fe and V Ions

The effect of X-ray irradiation on the absorption capacity of glass-like lithium tetraborate doped with iron and vanadium ions is studied. The concentration of additives varied from 0.02 to 0.9 at %. We study the optical absorption spectra of the synthesized glasses before and after irradiation. It is shown that the absorption capacity of irradiated glasses in the UV region sharply increases upon the introduction of V3+ and V4+ ions and also sharply decreases with the introduction of V5+ ions. The protective effect of iron ions is much less pronounced. The reason for the enhancement of the absorbance is an increase in the number of intrinsic electronic color centers, the maximums of the absorption bands of which are located in the ranges 350-400 and 550-560 nm. The data obtained makes it possible to estimate the band gap of glass-like lithium tetraborate and its change upon the introduction of iron and vanadium ions into the glass.