Neutron diffraction studies of the structure of Ge-based multicomponent sulphide glasses

摘要: Abstract We have used high real-space resolution pulsed neutron diffraction to investigate the structure of fibre-forming Ge-based multicomponent sulphide glasses. Diffraction patterns were measured up a maximum momentum transfer 40 A−1 for series seven samples from stoichiometric system Ge25(As,Ga)10S65, with Ga contents 0 10 at.%. The correlation functions all three principal peaks at 2.23, 2.97 and 3.49 A. first peak in is predominantly due Ge–S bonds, together smaller contributions As–S Ga–S bonds. second cation–cation distances between edge-sharing structural units. third mostly S–S within There also fine around functions, consisting small `pre-peak' ∼2.0 A larger broader shoulder ∼2.5 are no detectable changes composition pre-peak, whilst grows as gallium added glass. position 2.0 A, consistent either S22− disulphide groups unit, or bonds network, chemical disorder. According disorder model, 2.5 Ge–Ge network. If tetrahedrally coordinated then number these must increase replaces arsenic. Such an observed experimental data hence model preferred over model.