LOCAL STRUCTURE OF Eu^3+ IN BOROSILICATE GLASSES BY PHONON SIDEBAND SPECTRA

概要

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In xNa_2O・(40-x)B_2O_3・60SiO_2(mol%)(x=5, 10, 15, 20, 25, 30)glasses with 0.25mol% Eu_2O_3 as additive, the local structure around Eu^3+ was explored by employing the phonon sideband spectra of Eu^3+ associated with the ^5D_2←^7F_0 transition. It was found that the types and fraction of the structural units around Eu^3+ varied with glass composition. Moreover, the B-O vibrational mode of BO_3 unit exists around Eu^3+ when x ≨ 15, which is not present in the same composition glasses free of Eu^3+. A greatest asymmetry in the surrounding of Eu^3+ 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 Eu^3+. 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.
社団法人日本材料学会の論文
1998-12-15