Local structure of Eu3+ in borosilicate glasses by phonon sideband spectra

InxNa(2)O . (40-x)B2O3 . 60SiO(2) (mol%) (x = 5,10,15,20,25,30) glasses with 0.25mol% Eu2O3 as additive, the local structure around Eu3+ was explored by employing the phonon sideband spectra of Eu3+ associated with the D-5(2) <--F-7(0), transition. It was found that the types and fraction of the structural units around Eu3+ varied with glass composition. Moreover, the B-O- vibrational mode of BO3 unit exists around Eu3+ when x ≤ 15, which is not present in the same composition glasses free of Eu3+. A greatest asymmetry in the surrounding, of Eu3+ occurs at x = 10, inconsistent with a maximum of some physical properties found in sodium. borosilicate glasses at a Na:B ratio of about unity. In addition, various structural units possess different coordination preference to Eu3+. The highest theoretical microscopic optical basicity on the oxygen atoms in these units was advocated as a criterion of the coordination preference, which successfully elucidated a series of coordination preference phenomena occurring in silicate, borate and borosilicate glasses.