Structural study of AsS2–Ag glasses over a wide concentration range

Abstract (As 0.33 S 0.67 ) 100- x Ag x (0 ≤ x ≤ 28) bulk glasses showing micro-phase separation in a wide concentration range have been studied by X-ray diffraction, neutron diffraction and extended X-ray absorption fine structure measurements. The AsAgS 2 composition, which forms a homogeneous glass, is modeled with the reverse Monte-Carlo simulation technique. It is established that Ag prefers the environment of S; Ag―As bonding cannot be observed. Similarly to the AsAgS 2 crystalline modifications smithite and trechmannite, the main structural units of the glass are AsS 3 pyramids. The covalent network of As and S atoms becomes fragmented in the glassy AsAgS 2 unlike in the glassy AsS 2 . The environment of Ag atoms in the AsAgS 2 glass differs from that in the crystalline state. In average, each Ag atom has four nearest neighbors, three of them being S and one being Ag.