STRUCTURE AND REDOX CHEMISTRY OF TIN IN SnONaPO3 PSEUDO-BINARY GLASSES

• Published in: Journal of non-crystalline solids Vol. 291; no. 1-2; pp. 93 - 106
• Main Authors: Harish Bhat, M, Berry, F J, Jiang, J Z, Rao, K J
• Format: Journal Article
• Language: English
• Published: 01.01.2001
• ISSN: 0022-3093

Thermal and spectroscopic investigations have been carried out on a number of binary SnO-NaPO3 glasses over a wide range of compositions; SnO:NaPO3 from 0:100 to 45:55. Structures of the glasses have been investigated using Raman, FTIR, 31P-HR-MAS-NMR and 119Sn Mossbauer spectroscopies. 119Sn Mossbauer spectra suggests that there is an equilibrium of SnII(SnO) and SnIV(SnO2) in the glasses in the ratio 40:60 irrespective of the composition. 31P-MAS-NMR, IR and Raman spectra confirm the partial oxidation of SnO to SnO2. The unoxidized part of SnO in the glass acts as a modifier up to 27 mol% of nominal composition. Above this concentration, SnO acts as a glass former. SnO2 always behaves as a glass network former. A structural model has been proposed, which envisages SnIV as playing a key role in preserving part of the metaphosphate units in the structure so that SnO changes its role from a modifier to former above 27 mol% (SnO) concentration. The model is consistent with the behavior of Tg, molar volumes and compositional dependence of ir and Raman spectroscopic features. 44 refs.