Short range order Ge-S and Ge-(Ga,Sb)-S glasses

Ge-(Ga,Sb)-S glasses are widely used in infrared optics. Despite the practical importance their short range order is still not understood completely. The main problem is that both the size and scattering properties of Ge and Ga atoms are similar making it difficult to catch differences in their local environments experimentally. In addition, long Sb-S bonds were also found in Ge-Sb-S glasses, suggesting that SbS3 units may not be prevailing in this system. We aim to obtain structural models by combining neutron diffraction and x-ray diffraction structure factors (both up to at least 25 A-1) with X-ray absorption fine structure data. We believe that high real space resolution of GEM data will facilitate to detect potential differences in local order around Ge and Ga and it will also help to understand the origin of long Sb-S bonds.