Intermediate-range structure of amorphous GeSe2 alloy

Neutron and high-energy X-ray diffraction measurements have been carried out at KENS-KEK and SPring-8, in order to investigate detailed structures of amorphous GeSe2 prepared by the rapid quenching method. Considerable intermediate-range ordering is evident from the presence of a first sharp diffraction peak at low magnetides of the scattering vector. Well-defined first and second peaks are found at around 2.36 and 3.90 إ in the pair distribution function g(r). A small shoulder related to the existence of edge-sharing tetrahedral units is observed at a shorter r side of the second peak in g(r). Partial distribution functions, partial structure factors and bond-angle distributions can be obtained by Reverse Monte Carlo simulation. Results suggest that there are homo-polar bonds in tetrahedral structural units, and then the glass network is constructed by not only corner-sharing but also edge-sharing tetrahedra.