Structure And Optical Properties Of Teo2-Geo2 Glasses
TeO2-GeO2 glasses of the composition, TeO2 (1-x) - GeO2 (x) with x = 0.2 and 0.3 mol% were prepared by
conventional melt quenching method. FTIR and Raman analyses indicate the progressive transformation of the TeO4 units
into TeO3/ TeO3+1 units. The intensity of the Raman bands around 704/715 cm-1 and 781/804 cm-1 of the two compositions
increased with respect to the band 665/673 cm-1, confirming the formation of TeO3+1/TeO3 units at the cost of TeO4 units.
Absorption coefficient, optical energy gap, Urbach energy, refractive index, molar refractivity and polarizability values were
calculated using the absorption spectra. Defects increased with an increase in GeO2 content as indicated by an increase in
Urbach energy. Refractive index, molar refraction and polarizability decreased with an increase in GeO2 content while,
energy band gap and metallization criteria increased. It is concluded that the glass network is a mixture of TeO4,
TeO3/TeO3+1 and GeO4 structural units.
Keywords: Germanium Tellurite glasses, FTIR, Raman, Optical absorption.