Structural investigation of SnO-B2O3 glasses by solid-state NMR and X-ray photoelectron spectroscopy

Local structure of the SnO-B2O3 glasses was investigated using several spectroscopic techniques. B-11 MAS-NMR spectra suggested that BO4 tetrahedral units maximized at around the composition with 50 mol% SnO. The BO4 units were still present at compositions with high SnO content (67 mol% SnO), suggesting that SnO acted not only as a ;network modifier but also as a network former. O1s photoelectron spectra revealed that the addition of small amounts of SnO formed non-bridging oxygens (NBO) (B-O...Sn) and the amounts of NBO increased with an increase in SnO content. Sn-119 Mossbauer spectra indicated that Sn was present only as Sn(II) in the glasses. The structure of the SnO-B2O3 glasses was compared with that of conventional alkali borate glasses and lead borate glasses. The thermal and viscous properties of these glasses were discussed on the basis of the glass structure revealed in the present study. (C) 2002 Elsevier Science B.V. All rights reserved.