The reduction of tellurium in binary glasses in the system TeO2-Sb2O3

Although tellurite glasses have been well studied over the years, production of tellurium particles in glasses is reported for the first time. Glasses of the (1-x)TeO2 -xSb2O3 system were prepared and thermal and structural properties were characterized by Differential Scanning Calorimetry, Raman Spectroscopy and X-ray diffraction. The increase of Sb2O3 content in the glass composition as well as heat treatments lead to the darkening of the glasses and this process was accompanied by the UV-vis spectroscopy. The darkening process is related to the presence of Tellurium particles, which are obtained due to the oxi-reduction reactions of Sb2O3 when heated: Te4+ + 2Sb3+ → Te0 + 2Sb5+. Tellurium particles presence was confirmed by DSC curves, Raman scattering, Scanning Electron Microscopy and Energy Dispersive X-ray Spectrometry.