Chalcohalide glasses: The effect of covalent versus ionic bonding in (CuI)0.6(Sb2Se3)0.4

The Cu-Cu partial structure factor and related difference functions were measured for the four-component chalcohalide glass (CuI)0.6(Sb₂Se₃)0.4 by using the method of isotopic substitution in neutron diffraction. The Cu-Cu nearest-neighbors reside at a large distance of 4.06(3) {}, by contrast with metal chalcogenide glasses of high modifier content, and the corresponding coordination number is 1.9(3). Local structural motifs centered on Cu and Sb are deduced using a scheme where there is exclusive heteropolar bonding but where Cu-Sb and Se-I contacts are disallowed.