The role of Sb(5+) in the structure of Sb(2)O(3)-B(2)O(3) binary glasses--an NMR and Mössbauer spectroscopy study.
Glasses of general formula xSb(2)O(3) (1-x)B(2)O(3) (0 </= x </= 0.8) have been prepared by conventional melt- quenching. Mössbauer spectroscopy shows that a fraction of the Sb(3+) is converted to Sb(5+) and this fraction increases with x. High-field (11)B MAS NMR gives well-resolved resonances from boron atoms which are 3- and 4-coordinated to oxygen. The fraction of 4-coordinated boron, N(4), goes through a maximum value of 0.12+/-0.01 at x = 0.5. The position of the maximum in N(4) is consistent with the cation potential for Sb(3+), as observed for other systems. However, the low value of N(4) at this maximum is not so readily explained. The values are similar to those predicted if [BO(4)](-) were stabilised by [SbO(4)](+) but the trends with composition are different.
Holland
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D
Department of Physics, University of Warwick, Coventry CV4 7AL, UK. d.holland@warwick.ac.uk
Hannon
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Smith
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Johnson
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Thomas
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Beesley
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