Abstract: The structure of two Ge-As-Te glasses with compositions of Ge₁₀As₁₈Te₇₂ and Ge₁₅As₄₅Te₄₀ were studied by X-ray diffraction radial
distribution function analysis and Reverse Monte Carlo simulation. In the Ge₁₀As₁₈Te₇₂ glass, the Ge, As and Te atoms are bonded on average
to 3.55, 3 and 0.8 Te atoms, respectively. The structure of the investigated Ge₁₀As₁₈Te72 glass can be described as netwok of distorted GeTe_4 tetrahedra
and AsTe₃ (GeTe₃) pyramidal units , connected by --As(Ge)--Te--As(Ge)-- chain-like elements; In the Ge₁₅As₄₅Te₄₀ glass, there is one medium-range order dependent
X-ary scattering feature, i.e.,the first sharp diffraction peak(FSDP). The Ge atoms are bonded on average to 1.8 Te atoms and 1.1 As atoms. The As atoms are
bonded on average to 1.3 Te atoms and 1.0 As atoms. And the length of the Ge--Te bonds and As--Te bonds is shorter in the latter than in the former, respectively.

Key words: X-ray diffraction, Reverse Monte Carlo, chalcogenide, network