Boron atoms in these glasses are characterized by their high strength covalent B–O bonds, and by the modifier-dependence B4/B3 ratio, which is affected in its turn by the nature and concentration of the modifier oxides. Besides these units, a variety of anionic borate species (cyclic units), e.g., triborate or tetraborate groups that contain both three and four oxygen-coordi- nated boron atoms have been identified in various modification levels of borate glasses, by Raman and IR investigations