Neutron diffraction study on the medium and short-range order of ternary chalcogenide glasses

Glasses from Ge(x)As(40-x)S(6)0, Ge(x)As(40-x)Se(6)0, Ge(x)Sb(40-x)S(6)0 and Ge(x)Sb(40-x)Se(6)0 families have been investigated by neutron diffraction. The well expressed "first sharp diffraction peak" of the neutron spectra at Q = 10-14 nm(-1) has been explained by a pseudo-binary model of the structure of studied chalcogenide glasses. The amplitude of this interference maximum increases with Ge-content in all investigated samples. Experimental radial distribution functions show that the basic structural units, GeS(Se)(4) tetrahedra and As(Sb)S-3 or As(Sb)Se-3 pyramids persist in glassy state for the whole range of studied compositions. Crystal-like model distribution functions have been used to describe the short-range order observed. A shortening of heteropolar bonds in S-containing glasses as well as an increase of heteropolar bonds length in Se-containing glasses has been found. (C) 1999 Kluwer Academic Publishers.