Radiation Effects and Optical Properties of Aluminoborosilicate Glass Doped with RE Ions

The relationship between the oxidation-reduction state of rare-earth (RE) elements (Sm, Gd, Eu, Ce, Nd), optical properties and the structural evolution of aluminoborosilicate glasses is studied. The study of the optical characteristics of glass is carried out by measuring optical transmission and analyzing Raman spectra. It is found that the increase in the concentration of monovalent Nd ions leads to the broadening of the optical band of forbidden energies (the band gap Eg), while the larger content of multivalent Sm, Eu, and Ce ions significantly decreases its width. The narrowing of Eg results from the irradiation of glass with a high-energy electron flux (2.5 MeV, a dose of up to 109 Gy). The observed evolution is explained by the coexistence of different charge states and the local environments of RE ions in the studied glass. The presence of different charge states of RE ions causes an increase in the number of color centers, while variations in the local environment of ions change the amount of nonbridging oxygen in the structure.