Structure of silver bromide doped chalcogenide glasses

High-energy X-ray diffraction, neutron diffraction and extended X-ray absorption fine structure experiments have been carried out for (AgBr)x(As2Se3)1-x glasses. The addition of a large amount of AgBr does not significantly affect short-range orderings of the host network matrix. The interatomic distance of Ag-Br pairs in the present glass is much shorter than that of crystalline AgBr. Moreover, the coordination number of Ag ions is also different from the case of crystalline AgBr, and it decreases to be nearly four at x = 0.6. These results suggest that the basic structural motif around mobile Ag ions in the (AgBr)x(As2Se3)1-x glass is tetrahedral AgBr4 units as same as in the AgI-doped chalcogenide glass system AgI-As2Se3. It would be predictable that the structure model for AgBr-As2Se3 glasses is proposed to be a pseudo-binary mixture of the As(Se1/2)3 network matrix and AgBr-related conduction pathways.