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 (formula presented) by using the method of isotopic substitution in neutron diffraction. The Cu-Cu nearest-neighbors reside at a large distance of 4.06(3) Å, 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.