This result can be related to the presence of high percent (70 mol% Bi2O3) of heavy massive (Bi3+) ions which obviously
shield the effect of irradiation specifically in the UV region.
The generation of new induced visible band at 530 nm is related to positive hole center by the action of irradiation on the glass network itself including main phosphate or silicate or non-bridging oxygens as mentioned by several authors [10,13–20].