Nanomilling-driven Volumetric Changes in Melt-quenched Glassy Arsenoselenides Beyond the Border of Glass-forming Region

Changes in atomic-deficient structure driven by high-energy milling in dry and dry-wet regime (nanomilling) are recognized in glassy-crystalline g/c-As70Se30 and g/c-As75Se25 alloys beyond the border of glass-forming region in As-Se system employing positron annihilation lifetime (PAL) spectroscopy in a revised lifetime analysis. Nanomilling driven reamorphization of amorphous phase in the alloys compositionally shifted towards arsenic triselenide As2Se3 is confirmed by changes in diffuse peak-halos arrangement in their X-ray powder diffraction (XRPD) patterns. Preliminary characterization of the samples testify in favor of their glassy-crystalline nature, the crystalline phase being identified as rhombohedral arsenic As and cubic arsenolite As2O3, the content of the latter being increased after wet milling in the 0.5% PVP (Polyvinylpyrrolidone) water solution. Superposition of the PAL spectra for samples before and after milling in dry- and dry-wet regimes demonstrate spectacular rainbow-like behavior in the PAL spectra peaks and tails. The x3-x2-CDA (coupling decomposition algorithm) is employed to parameterize effects of volumetric nanostructurization in transition from dry-milled arsenoselenides to PVP-capped ones prepared by nanomilling in dry-wet regime. It is proved that positron trapping sites typical for dry-milled arsenoselenides with defect lifetimes approaching ~0.36-0.37 ns appear under this transition instead of Ps-hosting holes in PVP environment typical for wet-milled samples with Ps-related lifetime ~1.75 ns, these changes occuring in amorphous oxidized arsenoselenide matrix with bulk lifetime approaching ~0.26 ns.