Antimony and silicon environments in antimony silicate glasses

Abstract

Antimony silicate glasses, of general formula xSb 2O 3·(1− x)SiO 2 (0.1≤ x≤0.78), have been prepared by melt-quenching and their structures studied using 29Si MAS NMR spectroscopy, 121Sb Mössbauer spectroscopy and Raman spectroscopy. Oxidation during melting gives rise to Sb 5+ in concentrations, which increase linearly with x to give a value of ∼10% when x=0.78. 121Sb Mössbauer spectra show Mössbauer shifts and quadrupole splittings consistent with Sb 3+ in a [:SbO 3] trigonal pyramid, similar to that in crystalline Sb 2O 3. A broad band in the Raman spectrum at ∼410 cm −1 is due to the vibrations of such a unit. The dependence of the silicon Q n speciation on x can be interpreted by the formation of Sb–O–Sb links possibly to form rings of 4 [:SbO 3] units such as are found in valentinite.