The effect of oxygen substitution for sulphur has been investigated in germanium and boron based glasses containing heavy metal oxides (Sb203). After heat treatment under H2S flow, the colour of the glass changes from colourless to yellowish indicative of anion exchange. The oxygen substitution for sulphur has been confirmed by the presence of a new Raman band located at 240 cm-1 corresponding to a Ge-S and Sb-S bond vibration. The influence of the borate addition has been studied. XPS measurements have shown (i) the oxidation of Sb3+ to Sb5+ during the melting which increases with an increase of boron content and (ii) the reduction of Sb5+ to Sb3+ during the sulphination, resulting in the departure of more than one oxygen anion upon replacement by one sulphur and in the absence of weight gain.
