Antimony and silicon environments in antimony silicate glasses

Antimony silicate glasses, of general formula xSb2O3·(1−x)SiO2 (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 Sb5+ 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 Sb3+ in a [:SbO3] trigonal pyramid, similar to that in crystalline Sb2O3. 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 Qn speciation on x can be interpreted by the formation of Sb–O–Sb links possibly to form rings of 4 [:SbO3] units such as are found in valentinite.