Abstract
The ternary compounds Sn-x(GeSe2)(100-x) (0 <= x <= 24 at. %) were prepared in glassy thin films. Using the chemical bond approach, theoretical calculations of effects of Sn content on mean coordination number (CN), constraints number (N-s), molar volume (V-m), compactness (delta), heat of atomization (H-s), cohesive energy (CE), overall difference of electmnegativity (Delta chi) as well as the degree of iconicity (Ion) were discussed. Optical absorbance has been measured in order to evaluate experimentally the band gap (E-g) and the band tail's width (E-e). In addition, conduction-valence bands positions were estimated when changing Sn content. Increasing Sn content from 0 to 24 at. %, decreases E-g from 2.01 to 1.28 eV. Three theoretical estimations of the variations of the band gap with Sn content were critically compared to experimental values. Obviously, the combination of the estimated band gap from Delta chi and contributions of the formed bonds gives the best adjustment.