Nanomilling-driven volumetric changes in multiparticulate As 4 S 4 -bearing nanocomposites recognized with a help of annihilating positrons

Employing positron annihilation lifetime (PAL) spectroscopy, nanomilling-driven volumetric changes driven are identified in multiparticulate nanocomposites of As 4 S 4 –ZnS–Fe 3 O 4 system, considered in transitions between their respective hierarchical derivatives from triparticulate (1⋅As 4 S 4 /4⋅ZnS/1⋅Fe 3 O 4 ) to biparticulate (1⋅As 4 S 4 /1⋅Fe 3 O 4 , 1⋅As 4 S 4 /4⋅ZnS) and monoparticulate (As 4 S 4 ) ones. Unconstrained three-component PAL spectra of nanocomposites are parameterized in terms of positron-Ps trapping conversion obeying x3-x2-CDA (coupling decomposition algorithm). Coexistence of nanocrystalline nc-β-As 4 S 4 and amorphous a-AsS phase is shown to be crucial feature of these nanocomposites, the latter being generated continuously due to reamorphization of initial disordered phase and/or vitrification of nc-β-As 4 S 4 phase. The inverse positron-to-Ps trapping conversion prevails in transition from biparticulate (1⋅As 4 S 4 /1⋅Fe 3 O 4 ) and monoparticulate (As 4 S 4 ) nanocomposites (both dominated by trapping in As 4 S 4 -bearing sub-system) to triparticulate (1⋅As 4 S 4 /4⋅ZnS/1⋅Fe 3 O 4 ) one, disappeared positron traps being vacancy defects in a-As–S matrix, and Ps-decay sites formed instead being triple junctions between amorphized nc-β-As 4 S 4 grains. The normal Ps-to-positron-trapping conversion prevails in transition from biparticulate (1⋅As 4 S 4 /4⋅ZnS) nanocomposite dominated by positron trapping in ZnS sub-system to triparticulate (1⋅As 4 S 4 /4⋅ZnS/1⋅Fe 3 O 4 ) one, disappeared Ps-decay sites being triple junctions between amorphized nc-β-As 4 S 4 grains, and positron traps formed instead being vacancy-type defects in the packing of the finest ZnS crystallites (~ 2–3 nm).