Abstract
The possibilities surrounding positronics, a versatile noninvasive tool employing annihilating positrons to probe atomic-deficient sub-nanometric imperfections in a condensed matter, are analyzed in application to glassy arsenoselenides g-AsxSe100−x (0 < x < 65), subjected to dry and wet (in 0.5% PVP water solution) nanomilling. A preliminary analysis was performed within a modified two-state simple trapping model (STM), assuming slight contributions from bound positron–electron (Ps, positronium) states. Positron trapping in g-AsxSe100−x/PVP nanocomposites was modified by an enriched population of Ps-decay sites in PVP. This was proven within a three-state STM, assuming two additive inputs in an overall trapping arising from distinct positron and Ps-related states. Formalism of x3-x2-CDA (coupling decomposition algorithm), describing the conversion of Ps-decay sites into positron traps, was applied to identify volumetric nanostructurization in wet-milled g-As-Se, with respect to dry-milled ones. Under wet nanomilling, the Ps-decay sites stabilized in inter-particle triple junctions filled with PVP replaced positron traps in dry-milled substances, the latter corresponding to multi-atomic vacancies in mostly negative environments of Se atoms. With increased Se content, these traps were agglomerated due to an abundant amount of Se-Se bonds. Three-component lifetime spectra with nanostructurally- and compositionally-tuned Ps-decay inputs and average lifetimes serve as a basis to correctly understand the specific “rainbow” effects observed in the row from pelletized PVP to wet-milled, dry-milled, and unmilled samples.
Highlights
Chalcogenide compounds represented by glassy arsenoselenides, g-AsxSe100−x, from “pure” selenium g-Se to stoichiometric g-As40Se60 and stretched further with As content beyond arsenic triselenide g-As2Se3, to As-rich g-As65Se35, compose an important family of archetypal media possessing widespread application in optoelectronics, IR photonics, opto- and space telecommunication, bio- and chemical sensing, etc. [1,2,3]
Volumetric effects, involving changes in atomic-deficient free-volume structure, were studied in glassy arsenoselenides g-AsxSe100−x subjected to high-energy dry and wet milling employing the method of positron annihilation lifetime (PAL) spectroscopy
Preliminary analysis of milling-driven volumetric nanostructurization in g-AsxSe100−x was performed with a modified two-state simple trapping model applied under slight input from a Ps-decay channel
Summary
Chalcogenide compounds represented by glassy arsenoselenides, g-AsxSe100−x, from “pure” selenium g-Se to stoichiometric g-As40Se60 (the group of under-stoichiometric arsenoselenides) and stretched further with As content beyond arsenic triselenide g-As2Se3 (viz. g-As40Se60), to As-rich g-As65Se35 (the group of over-stoichiometric arsenoselenides), compose an important family of archetypal media possessing widespread application in optoelectronics, IR photonics, opto- and space telecommunication, bio- and chemical sensing, etc. [1,2,3]. G-As40Se60), to As-rich g-As65Se35 (the group of over-stoichiometric arsenoselenides), compose an important family of archetypal media possessing widespread application in optoelectronics, IR photonics, opto- and space telecommunication, bio- and chemical sensing, etc. Atomic-deficient structures of glassy arsenoselenides, g-AsxSe100−x, from glass-forming regions, covering under-stoichiometric (0 < x < 40) and over-stoichiometric (40 < x < 65) domains activated by NM in dry and wet mode (i.e., milled in PVP medium), was comprehensively analyzed, employing positronics, recognized as an advanced highinformative noninvasive tool probing sub-nm-scaled volumetric effects in a condensed matter, grounded on positron (e+) annihilation lifetime (PAL) spectroscopy [16,17,18,19,20,21,22,23,24,25,26]
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