Local Structure Of Eu3⁺ In Borosilicate Glasses By Phonon Sideband Spectra

InxNa2O (40-x)B₂O₃ 60SiO₂ (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 5D2 ⃪7F0 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 B03 unit exists around Eu3⁺ when x ≦ 15, which is not present in the same composition glasses free of Eu^3-. 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.