The optical band gap and the tailing states determination in glasses of TeO2-V2O5-K2O system

Ternary amorphous samples of 50TeO 2 -(50 − x )V 2 O 5 - x K 2 O compositions with 0 ≤ x ≤ 20 (in mol %) have been prepared using the press-melt quenching method. The optical absorption spectra of glass have been recorded in the wavelength range 300–900 nm by UV-visible spectrophotometer. According to The Tauc and Urbach theories, the optical band gap and width of the tail of localized states have been evaluated. In addition the temperature glass transition ( T g ) of glasses have been determined by differential scanning calorimetry, confirming the amorphous nature of samples. The density and molar volume have been studied, indicating act of K 2 O as network modifier.