The modification of structural, thermal and optical properties of Se-Ge-Sb glasses by addition of arsenic element was the goal of this study. In this regards, six different glasses of Se60Ge40-xSb5Asx (0 x 15) were prepared by conventional melt quenching technique in quartz ampoule. The produced samples were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), UV–Vis–NIR spectrophotometer, Fourier transform infrared (FTIR) and Raman spectroscopy. The fundamental absorption edge for of the glasses was analyzed in terms of the theory proposed by Davis and Mott. Based on the obtained results, the glass transition temperature, optical energy gap and Urbach energy of prepared glasses in this alloying system were in the range of 325–380 C, 1.43–1.64 eV and 0.03–0.3547 eV, respectively. The as prepared glasses show anomalous behavior at 5–7.5 mole% of arsenic for the glass transition temperature, transmittance, absorption edge, optical energy gap and Urbach energy. Based on the Raman spectra, the structural analysis indicates that, increasing the network connectivity upon increasing the arsenic content up to 7.5 mole% is the main reason of anomalous behavior in Se60Ge40-xSb5Asx (0 x 15) system.
