Milling-driven nanonization of As S100- alloys from second glass-forming region: The case of higher-crystalline arsenicals (51<x<56)

Nanonization accompanied by amorphization processes driven by high-energy mechanical milling are studied in As _xS _100-x alloys from higher-crystallinity domain (51< x<56) employing multiexperimental approach. Principal disproportionality in these arsenicals under milling comprises molecular-to-network transformations resulting in β-As ₄S ₄ polymorph supplemented by isocompositional amorphous phase. Nanosized state is signalized in broadened Raman-active bands of β-As ₄S ₄ crystallites (~40–50 nm), the milling-driven nanonization being accompanied by disappearing of other crystalline phases (pararealgar, χ-phase As ₄S ₄, low-temperature dimorphite α-As ₄S ₃). At high As content in studie alloys, milling facilitates disappearing of low-temperature α-As ₄S ₃ at cost of nanosized high-temperature β-As ₄S ₄ and α′-As ₄S ₃ phases. These transformations are clarified with heat capacity measurement showing depressing and splitting trend in melting and interphase-transition temperatures from normal-crystalline α′-As ₄S ₃ to plastic-crystalline β-As ₄S ₃. Intermediate-range ordering of the amorphized AsS phase is enhanced under milling, this phase dominating in network derivatives from As ₄S ₄ cage-like molecules, while generation of competitive As-rich phase being expected at higher As content.