Short-range order of germanium selenide glass

Chalcogenide Ge20Se80 glass was prepared using the melt-quench technique. The radial distribution function is obtained from X-ray diffraction data in the scattering vector interval 0.28 <= K <= 6.87 angstrom(-1). Reverse Monte Carlo (RMC) simulations are useful to compute the partial pair distribution functions, partial structure factors, S (ij)(K), and total structure factor. Values of r (1)/r (2) ratio and bond angle (Theta) indicate that Ge(Se-A1/2)(4) tetrahedra units connected by chains of the chalcogen atoms are present. The partial structure factors have shown that homopolar Ge-Ge and Se-Se bonds are behind the appearance of the first sharp diffraction peak in the total structure factor. Tetrahedral Ge(Se-A1/2)(4) structural units connected by Se-Se chains have been confirmed by the simulated values of the partial coordination numbers and the bond angle distributions. Finally, Raman spectra measurements have strongly supported the conclusions obtained either from the calculated Fourier data or from RMC simulations.