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Nanostructurization-driven responses in calorimetric heat-transfer phenomena are compared for glassy arsenoselenides at different levels of their molecular network organization, namely in high-polymerized g-As5Se95 and low-polymerized g-As55Se45, employing multifrequency temperature-modulated DSC-TOPEM® method complemented with Raman scattering microspectroscopy. It is shown that high-polymerized network composed of AsSe3 pyramids interlinked by Se chains with small number of Se8 molecular units decoupled from this network prevails in melt-quenched and nanomilling-derived g-As5Se95. Transition to more polymerized network due to incorporation of destroyed Se8 molecules into glass backbone occurs in this glass under nanostructurization. As a result, nanostructurization-driven calorimetric response in g-As5Se95 dominates by size-induced glass-transition temperature depression. The low-polymerized structure of g-As55Se45 is built of As–Se network enriched with tetra-arsenic selenide molecular units decoupled from this network. Molecular-to-network transition owing to nanomilling-driven destruction of these cage molecules and their incorporation into newly polymerized glass-forming backbone occurs in g-As55Se45 resulting in strong increase in calorimetric glass-transition temperature.

NIR-shielding window materials were fabricated by direct embedding of Ta0.3W0.7O2.85 nanocrystals in bulk borosilicate glass-ceramics during a facile melt-quenching process. Optical and thermal performance of the prepared windows can be adjusted by varying the concentration of H2WO4 and Ta2O5 in the starting materials. The optimized window fabricated from raw materials containing 4.5?mol% H2WO4 and 0.3?mol% Ta2O5 exhibited high visible light transmittance 74.4% and strong NIR-shielding ability ?T?=?68.9%. Its thermal insulation performance is much better than soda lime glass or ITO glass, and its visible light transmission is higher than cesium-tungsten-bronze-based film coated glass. The distribution of Ta0.3W0.7O2.85 functional nanocrystals in the glass matrix was confirmed by sample characterization using XRD, Raman, XPS, HRTEM and EDS. The NIR-shielding property has been attributed to local surface plasmon resonance due to oxygen vacancies in the Ta0.3W0.7O2.85 nanocrystals. This study sheds a light on fabricating energy-saving windows with a tunable NIR-shielding performance.

International audience; A photosensitive medium based on amorphous equichalcogenide thin films containing germanium and antimony is proposed with characteristics promising for applications in all-chalcogenide photonics, sensors, and photovoltaics. Optical properties, temperature, and exposure wavelength dependence of DC electrical conductivity are shown to be comparable with those for halide perovskites, which potentially makes amorphous equichalcogenides a very attractive alternative. The change in dark resistivity with temperature is found to follow exponential decay, covering 2 orders of magnitude over a 70 K temperature interval. Light exposure leads to several orders of relative changes in a current when compared to its dark value. A strong photocurrent response is observed under low power (milliwatts range) exposure across the entire 400-1000 nm range of the investigated wavelengths. An increase in temperature leads to a decrease in the photoresponse of the developed material, which is found to vanish at temperatures higher than 120 degrees C when only a few milliwatts of exposure power is used.

Complete hierarchy of network amorphization scenarios initiated in AsxS100-x nanoarsenicals within As4S4-As4S3 cut-Sect. (50 ≤ x ≤ 57) is reconstructed employing materials-computational approach based on ab-initio quantum-chemical modeling code (CINCA). Under nanostructurization due to high-energy mechanical milling, the inter-crystalline transformations to nanoscopic β-As4S4 phase accompanied by appearance of covalent-network amorphous matrix are activated. General amorphization trend under nanomilling obeys tending from molecular cage-like structures to optimally-constrained covalent-bonded networks compositionally invariant with parent arsenical. The contribution of amorphization paths in nanoarsenicals is defined by their chemistry with higher molecular-to-network barriers proper to As4S3-rich alloys. The generated amorphous phase is intrinsically decomposed, possessing double-Tg relaxation due to stoichiometric (x = 40) and non-stoichiometric (x > 40) sub-networks, which are built of AsS3/2 pyramids and As-rich arrangement keeping (i) two separated As-As bonds derived from realgar-type molecules, (ii) two neighboring As-As bonds derived from pararealgar-type molecules or (iii) three neighboring As-As bonds in triangle-like geometry derived from dimorphite-type molecules. Compositional invariance of nanoamorphous phase is ensured by growing sequence of network-forming clusters with average coordination numbers Z in the row (As2S4/2,Z = 2.50) – (As3S5/2, Z = 2.55) – (As3S3/2, Z = 2.67). Diversity of main molecular-to-network amorphizing pathways in nanoarsenicals is reflected on the unified potential energy landscape specified for boundary As4S4 and As4S3 components.

This research is intended to compare degradation processes in light-cured (dimeth)acrylate-type polymer/filler dental composites affected to aging in dry-air and water-immersed mode. The positron annihilation lifetime (PAL) spectroscopy has been employed to study changes in atomic-deficient structure in these composites under aging. Under light-curing polymerization initiating crosslinking of monomer chains, fragmentation of free-volume holes in resin matrix dominates over enhanced fraction of trapped positrons, since filler–particles assemblies get to be more tightly covered by surrounding polymer causing disappearing of interfacial voids at the filler–polymer surface. Therefore, the PAL spectra-transforming trend in light-cured composites obeys inverse positron-to-Ps trapping conversion. In contrast, the PAL spectra-transforming trend in these restoratives under aging obeys direct Ps-to-positron trapping conversion. After dry-air aging, the observed changes in the density of annihilation sites are ascribed to a strong agglomeration of Ps-decay holes in polymer sub-system accompanied by weaker agglomeration and appearance of positron traps in filler–polymer sub-system. Under the water aging, the agglomeration of Ps-decaying holes in the polymer sub-system is suppressed due to absorbed water molecules, this effect being slightly revealed at lower polymerization. New positron traps are observed at the filler–polymer interfaces in all light-cured composites. The agglomerated Ps-decay holes in a polymer matrix and positron traps inside filler–particles assemblies and filler–polymer interfaces of artificially aged composites cause their progressive microcracking.

Amorphization scenarios in multiparticulate grinding media composed of As4S4/ZnS/Fe3O4 nanocomposites driven by high-energy ball mechanical milling are identified employing the X-ray powder diffraction analysis on intermediate-range ordering in the generated amorphous phase. This amorphous phase is supposed to be nucleated heterogeneously from grain boundaries of β-As4S4 crystallites followed by penetration deeply into grain interior, stabilizing the crystalline-amorphous core-shell structure of the fine-grained nanoparticles. Coexistence of nanocrystalline nc-β-As4S4 and amorphous arsenic monosulphide a-AsS phases is crucial feature of these nanocomposites, the amorphous substance being generated continuously due to re-amorphization of disordered phase initially existed in arsenic sulphide prepared by synthesis from elements and direct milling-driven vitrification of nc-β-As4S4. In monoparticulate β-As4S4-based and biparticulate As4S4/Fe3O4 nanocomposites, the amorphizing configurations are composed of single- and triple-broken chain-like network clusters. Under stronger conditions realized in the grinding medium composed by hard nanoparticles biased by their sizes in respect to 20:1 rule, as in triparticulate 1⋅As4S4-4⋅ZnS-1⋅Fe3O4 nanocomposite, the amorphization scenario differs being activated by double-breaking of intramolecular covalent bonds within As4S4 cage-like molecules. This effect is identified as nanocrystalline nc-ZnS-assisted milling-driven arsenic monosulphide amorphization in triparticulate 1⋅β-As4S4-4⋅ZnS-1⋅Fe3O4 nanocomposite solution.

International audience; This is an introduction to the feature issue of Optical Materials Express on Non-Oxide Optical Materials. © 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

The effect of a weak magnetic field (B = 0.17 T) and X-irradiation (D < 520 Gy) on the rearrangement of the defective structure of near-surface p-type silicon layers was studied. It was established that the effect of these external fields increases the positive accumulated charge in the region of spatial charge (RSC) and in the SiO2 dielectric layer. This can be caused by both defects in the near-surface layer of the semiconductor and impurities contained in the dielectric layer, which can generate charge carriers. It was found that the near-surface layers of the barrier structures contain only one deep level in the silicon band gap, with an activation energy of Ev + 0.38 eV. This energy level corresponds to a complex of silicon interstitial atoms SiI+SiI. When X-irradiated with a dose of 520 Gy, a new level with the energy of Ev + 0.45 eV was observed. This level corresponds to a point boron radiation defect in the interstitial site (BI). These two types of defect are effective in obtaining charge carriers, and cause deterioration of the rectifier properties of the silicon barrier structures. It was established that the silicon surface is quite active, and adsorbs organic atoms and molecules from the atmosphere, forming bonds. It was shown that the effect of a magnetic field causes the decay of adsorbed complexes at the Si–SiO2 interface. The released hydrogen is captured by acceptor levels and, as a result, the concentration of more complex Si–H3 complexes increases that of O3–Si–H.

In this research, blood samples of 47 patients infected by COVID were analyzed. The samples were taken on the 1st, 3rd and 6th month after the detection of COVID infection. Total antibody levels were measured against the SARS-CoV-2 N antigen and surrogate virus neutralization by serological methods. To differentiate COVID patients with different antibody levels, Fourier Transform InfraRed (FTIR) and Raman spectroscopy methods were used. The spectroscopy data were analyzed by multivariate analysis, machine learning and neural network methods. It was shown, that analysis of serum using the above-mentioned spectroscopy methods allows to differentiate antibody levels between 1 and 6 months via spectral biomarkers of amides II and I. Moreover, multivariate analysis showed, that using Raman spectroscopy in the range between 1317 cm

Thermal-alteration interphase transformations in natural (realgar α-As4S4 of two mineral origins) and synthetic (commercial powdered high-temperature β-As4S4 modification synthesized from elemental constituents and subjected to high-energy mechanical ball milling) arsenic monosulfide polymorphs are studied exploring temperature-modulated DSC TOPEM® method. Specific heat capacity and non-reversing heat flow variations in realgar α-As4S4 demonstrate two endothermic events, these being ascribed to interphase α → β transformation at ∼(540–550) K, and melting of this newly-formed high-temperature β-As4S4 phase at 581–582 K. This polymorph originated from thermal alteration of mineral realgar possesses congruent melting in contrast to synthetic β-As4S4 polymorph, which shows non-equilibrium melting due to accompanied generation of compositionally-authentic amorphous phase. Calorimetric studies on synthetic β-As4S4 in powdered coarse-grained and milled states demonstrate complicated non-equilibrium melting in principally different crystalline-amorphous environments along with crystal-to-glass transformation. Structural-chemical heterogeneity of β-As4S4 crystallites results in incongruent double-peak melting through two endothermic events at ∼578 K and ∼588 K. The amorphous phase formed under high-energy milling of synthetic β-As4S4 possesses a dual nature due to stabilization of As-rich glassy substances with low- and high-temperature glass transition mid-points. This process in the powdered synthetic β-As4S4, identified as re-amorphization of initial amorphous phase and direct vitrification from β-As4S4 crystallites, was parameterized as compared to calorimetric thermal-alteration events in orpiment As2S3 mineral.

Temperature-modulated DSC TOPEM® method was applied to study amorphization in directly synthesized high-temperature polymorph of tetra-arsenic tetra-sulfide β-As4S4 affected to high-energy mechanical milling in a dry mode with 100–600 min−1 rotational speeds. The appeared amorphous phase is shown to possess dual nature, being related to As-rich glassy-like substances with low- and high-temperature glass transition midpoints. In respect of DSC TOPEM® studies, the crystalline–amorphous heterogeneity of chemical environment around β-As4S4 crystallites results in incongruent double-peak melting revealed through two endothermic effects at~ 305 °C and ~ 315 °C. Amorphous phase continuously generated under ball milling with increased rotational speed is identified as compositionally authentic to arsenic monosulfide, but different in medium-range order from stoichiometric As2S3. The overall amorphization in commercial arsenic sulfide prepared by direct synthesis from elemental constituents under high-energy ball milling occurs from two sources, these being high-to-low-Tg amorphous phase transformation and direct vitrification of β-As4S4 phase. These data testifies in favor of “shell” model treated solid-state amorphization in terms of defect generation in parent β-As4S4 phase, the amorphous substance being nucleated heterogeneously from grain boundaries followed by stretching into crystalline grain interior.

The amorphization is studied in mechanically activated β-As4S4 using high-energy ball milling in a dry mode with 100–600 min−1 rotational speeds, employing complementary methods of X-ray powder diffraction (XRPD) related to the first sharp diffraction peak, positron annihilation lifetime (PAL) spectroscopy, and ab initio quantum-chemical simulation within cation-interlinking network cluster approach (CINCA). The amorphous substance appeared under milling in addition to nanostructurized β-As4S4 shows character XRPD halos parameterized as extrapolation of the FSDPs, proper to near-stoichiometric amorphous As–S alloys. The structural network of amorphized arsenicals is assumed as built of randomly packed multifold cycle-type entities proper to As4S4 network. The depressing and time-enhancing tendency in the PAL spectrum peak is direct indicative of milling-driven amorphization, associated with free-volume evolution of interrelated positron- and Ps-trapping sites. At lower speeds (200–500 min−1), these changes include Ps-to-positron trapping conversion, but they attain an opposite direction at higher speed (600 min−1) due to consolidation of β-As4S4 crystallites. In respect of CINCA modeling, the effect of high-energy milling is identified as destruction–polymerization action on monomer cage-type As4S4 molecules and existing amorphous phase, transforming them to amorphous network of triple-broken As4S4 derivatives. These findings testify in a favor of “shell” kinetic model of solid-state amorphization, the amorphous phase continuously generated under speed-increased milling being identified as compositionally authentic to arsenic monosulfide, different in medium range ordering from stoichiometric As2S3.

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.

Competitive pathways of nanostructurization-driven molecular-network disproportionality due to decomposition of dimorphite-type As4S3 phase were identified in over-stoichiometric AsxS100−x arsenicals (57

International audience; Effect of high-energy mechanical milling on glassy AsxSe100 - x (5

International audience

Thermochemical events recognized from heat flux DSC measurements involving dynamic and progressive step-cycling are identified in multi-nanophase substances exemplified by melt-quenched and nanomilling-derived AsxS100-x arsenicals enriched in As over As4S3 composition (As60S40, As62S38, As64S36). Thermal-alteration heat transfer in these alloys composed of normal- and plastic-crystalline phases supplemented by dual-nature amorphous substance are complicated by transformations in nanocrystalline dimorphite-type As4S3 and realgar-type As4S4 phases. Primary calorimetric events in the examined nanoarsenicals are shown to be as follows: (i) reduction in onset temperature from normal- (α′-As4S3) to plastic-crystalline (β-As4S3) phase; (ii) depression in pre-melting temperature of β-As4S3 phase; (iii) decrease in decomposition temperature of dimorphite-type phase supplemented by appearance of realgar-type β-As4S4 and amorphous phase, (iv) increase in crystallization temperature of β-As4S3 phase; (v) high-temperature shift in relaxation from liquid to stabilized heterogeneous state. The multiphase occurrence of nanoarsenicals results in unexpected increase in some heat transfer events detected in reheating modes.

Arsenic sulphide β-As4S4 has been modified by mechanical activation in a planetary ball mill. As a consequence, the solid-state properties and dissolution yield have been influenced. The following changes were observed: the increase of specific surface area, changes in the morphology (the formation of submicron particles), the occurrence of nanoparticles (21–31 nm), changes in crystal lattice parameters and changes in the Raman shift of particular vibrations. As a consequence of these changes, the dissolution rate of β-As4S4 has been increased, which is a challenge for the application in cancer research.

Positron annihilation lifetime (PAL) spectroscopy was applied for the first time to study free-volume void evolution in chalcogenide glasses of Ga–Ge–Te/Se cut-section exemplified by glassy Ga 10 Ge 15 Te 75 and Ga 10 Ge 15 Te 72 Se 3 doped with 500 ppm of Tb 3+ or Pr 3+ . The collected PAL spectra reconstructed within two-state trapping model reveal decaying tendency in positron trapping efficiency in these glasses under rare-earth doping. This effect results in unchanged or slightly increased defect-related lifetimes τ 2 at the cost of more strong decrease in I 2 intensities, as well as reduced positron trapping rate in defects and fraction of trapped positrons. Observed changes are ascribed to rare-earth activated elimination of intrinsic free volumes associated mainly with negatively-charged states of chalcogen atoms especially those neighboring with Ga-based polyhedrons.

The Ge20Ga5Sb10S65 glasses doped with Er3+ ions (0; 0.1; 0.5; 1.0 mol. %) are investigated with optical, fluorescence and positron annihilation lifetime (PAL) spectroscopies. The optical and fluorescence measurements were performed at room (TR) and liquid nitrogen (TLN) temperatures. Transitions of Er3+ ions from the 4I15/2 ground energy level to their higher levels 4F9/2, 4I9/2, 4I11/2 and 4I13/2 are well observed at both temperatures as absorption peaks at ~660, 810, 985 and 1540 nm, respectively. At TLN temperature, it is also possible to resolve the absorption band at ~550 nm, which corresponds to 4I15/2→4S3/2 transition. The most intense fluorescence emission is observed at ~1 μm and ~1.5 μm wavelengths, which are identified as 4I11/2→4I15/2 and 4I13/2→4I15/2 radiative transitions of Er3+ ions. It is shown by PAL spectroscopy, that the addition of Er causes an increase of positron lifetime in defects τ2 and a decrease in the intensity I2 of the corresponded lifetime component. These changes are explained in terms of positron trapping reduction due to the occupation of positron trapping Ga-based sites in the glass matrix by Er3+ ions.

The applicability of positron annihilation lifetime (PAL) spectroscopy to identify volumetric changes in nanostructured polymer/filler substances is first verified at the example of commercially available dimethacrylate-based dental restorative composites Charisma® (Heraeus Kulzer GmbH, Germany) affected to light-curing photopolymerization and one-year dry physical ageing. Principal channel governing PAL spectra in these nanocomposites is recognized as mixed positron-Ps trapping, where positronium Ps (i.e. bound positron-electron state) decay occurs in free-volume holes localized preferentially in polymer matrix, while free positron self-annihilation is character for interfacial voids at the surface of filler-particles assemblies in the filler and/or mixed filler-polymer environment. Methodological algorithm for experimental PAL spectra refinement referred to as the x3-x2-CDA (coupling decomposition algorithm) is validated for these nanocomposites, obeying changes in atomic-deficient structure due to direct conversion between positron-trapping and Ps-decaying sites. Straightforward parameterization of the reconstructed PAL spectra allows meaningful identification of free-volume entities responsible for nanostructurization-driven transformations.

Nanostructurization through high-energy mechanochemical milling is reconsidered as an effective method of biomedical engineering of anticancer drugs possessing poor availability in human organisms. In this research, the nanoparticles (NPs) of arsenic sulfides As4S4 combined with ZnS ones prepared by dry milling as As4S4/ZnS nanocomposites or wet milling in water solution of biocompatible copolymer Poloxamer 407 as suspensions are analyzed in respect of compositionally guided anticancer activity. A multiexperimental approach involving both atomic-specific and atomic-deficient methods supported by a structure-morphology study is applied to characterize this NP-based system. A hierarchical model considering free-volume elements between interacting crystallites and their agglomerates is developed to assess positron annihilation lifetime data treated within ×3-term fitting and ×3-×2-coupling decomposition algorithm. A compositionally dependent nanoformulation is represented as a common stabilization of coarse-grained As4S4 and fine-grained ZnS NPs accompanies by positron-to-positronium trapping conversion. An anticancer effect on A375 and Bowes melanoma cell lines clearly confirms the improved biomedical efficacy of the developed As4S4-ZnS nanosystem.

International audience; Atomic-deficient void structure is studied in nanocomposites prepared by mechanochemical milling of glassy g-As2Se3 in a water solution of polyvinylpyrrolidone (PVP) employing positron annihilation lifetime spectroscopy. Formalism of Ps-to-positron trapping conversion known as x3-x2-CDA (coupling decomposition algorithm) is applied to identify free-volume defects in the pelletized g-As2Se3/PVP nanocomposite in respect to dry-milled g-As2Se3 one. Under wet-milling, the inter-nanoparticle Ps-decaying sites in preferential PVP environment replace free-volume positron traps (in dry-milled g-As2Se3) with defect-specific lifetime of 0.352 ns, corresponding to di-/tri-atomic vacancies in g-As-Se. © 2018 Author(s).

Positron annihilation lifetime spectroscopy was applied to characterize free-volume structure of polyvinylpyrrolidone used as nonionic stabilizer in the production of many nanocomposite pharmaceuticals. The polymer samples with an average molecular weight of 40,000 g mol(-1) were pelletized in a single-punch tableting machine under an applied pressure of 0.7 GPa. Strong mixing in channels of positron and positronium trapping were revealed in the polyvinylpyrrolidone pellets. The positron lifetime spectra accumulated under normal measuring statistics were analysed in terms of unconstrained three- and four-term decomposition, the latter being also realized under fixed 0.125 ns lifetime proper to para-positronium self-annihilation in a vacuum. It was shown that average positron lifetime extracted from each decomposition was primary defined by long-lived ortho-positronium component. The positron lifetime spectra treated within unconstrained three-term fitting were in obvious preference, giving third positron lifetime dominated by ortho-positronium pick-off annihilation in a polymer matrix. This fitting procedure was most meaningful, when analysing expected positron trapping sites in polyvinylpyrrolidone-stabilized nanocomposite pharmaceuticals.

The nature of intrinsic phase separation initiated under different homogenization routes is studied in arsenic trisulfide As2S3 glass using Raman scattering spectroscopy. It is shown that As2S3 glass prepared within conventional melt-quenching route is subjected to essential phase separation dependent on the homogenization of elemental constituents sealed in evacuated ampoules. Under condition of low-temperature homogenization at 450–550 °С, chemical interaction due to limited solubility of liquid S in solid As results in structurally intrinsic As- and S-rich phases with high content of homoatomic As–As and S–S bonds, respectively, which are “wrong” from the point of As2S3 stoichiometry This process can be essentially facilitated with more rapid heating and greater amount of initial elemental ingredients taken for synthesis. During prolonged homogenization of this intrinsically-decomposed melt (such as lasting 2 days in a rocking furnace), these products are partially separated giving main glassy phase enriched on As in the form of realgar- and dimorphite-type molecules, isolated As–As bonds in a glassy network and volatilized S-rich phase, which condenses on the walls of ampoules. If such melt is insufficiently homogenized as under 6-h heating at 500 °C with only 2-h rocking, the coordination disordering is maintained in the ultimate glass. This provides that volatilized S-rich phase does not form, and all decomposition products are stabilized in glassy state as quasi-tetrahedral units and compensating homoatomic As–As bonds.

Within this study, a stable nanosuspension of silver nanoparticles (Ag NPs) was prepared using a two-step synthesis and stabilization approach. The Ag NPs were synthesized from a silver nitrate solution using the Origanum vulgare L. plant extract as the reducing agent. The formation of nanoparticles was finished upon 15 min, and subsequently, stabilization by polyvinylpyrrolidone (PVP) using wet stirred media milling was applied. UV-Vis spectra have shown a maximum at 445 nm, corresponding to the formation of spherical Ag NPs. Infrared spectroscopy was used to examine the interaction between Ag NPs and the capping agents. TEM study has shown the formation of Ag NPs with two different average sizes (38 ± 10 nm and 7 ± 3 nm) after the plant-mediated synthesis, both randomly distributed within the organic matrix. During milling in PVP, the clusters of Ag NPs were destroyed, the Ag NPs were fractionized and embedded in PVP. The nanosuspensions of PVP-capped Ag NPs were stable for more than 26 weeks, whereas for the non-stabilized nanosuspensions, only short-term stability for about 1 week was documented.

International audience; We report results on the processing and characterization of different glass preforms and single core fibers within the SiO2-Na2O-B2O3-Er2O3-P2O5-Al2O3 system. Micro-Raman spectroscopy was used to identify post-draw structural modification. The differences in the micro-Raman spectra recorded on the preform and on the fiber glass were attributed to a change in the structure induced by the drawing process. Changes in the silicate network organization and small scale molecular orientation within the glass matrix are suspected to occur during the fiber drawing process. We found that the extent in the changes between the preform and fiber properties depend on the glass composition. The glass network of the Al-containing fiber is expected to be less sensitive to the drawing process than that of the fiber matrix as the network of this Al-containing fiber is formed by a larger number of Si-BO units in the network and neutral three-coordinated boron compared to the network of the fiber matrix. From the micro-Raman spectra, formation of small crystals is suspected to occur in the P-containing glasses during the fiber drawing process. The resulting fibers were found to have propagation losses at 1330 nm and Er3+ absorption between (7 ± 1) and (25 ± 1) dB/m and (36 ± 1) and (47 ± 1) dB/m, respectively, depending on the glass composition.

Amorphization scenarios in multiparticulate nanocomposites based on directly synthesized β-As4S4 activated by high-energy mechanical milling are identified employing X-ray diffraction analysis complemented with ab initio quantum-chemical computational modelling. Coexistance of nanocrystalline and amorphous phases is crucial feature of these nanocomposites, their medium-range structure being reconstructed assuming diffuse halos as arising from remnants of inter-planar correlations with ∼5.3–5.5 Ǻ Bragg-diffraction spacing supplemented by Ehrenfest-diffraction contribution from most pronounced inter-molecular correlations. Full hierarchy of molecular-breaking events comprising transitions from As4S4 cage-like molecule to its network-forming derivatives is computed. The optimally-constrained single-broken clusters keeping one hexagon and two adjacent pentagons in atomic arrangement are supposed to be responsible for amorphization in β-As4S4. The over-constrained triple-broken chains are character for amorphization in monoparticulate (composed exceptionally by β-As4S4 crystallites) and biparticulate (composed by mixed β-As4S4 and magnetite Fe3O4 crystallites) grinding media, the estimated density of accompanied amorphous phase being 3.43 g⋅ cm−3. Strong amorphization scenario obeying “shell” kinetics model occurs in triparticulate β-As4S4-based solution modified by Fe3O4 (few tens nm) and ZnS (below few nm) crystallites. The latter acting as solid solvent provide sufficient energy gained from collisions with hard magnetite particles to soft amorphized substance composed mainly by double-broken As4S4 molecules keeping pentagon rings in atomic arrangement. This effect is identified as ZnS-assisted milling-driven arsenic monosulphide amorphization in 1⋅β-As4S4-4⋅ZnS-1⋅Fe3O4 grinding solution.

Crystallization effects in Te20As30Se50 glass known also as TAS-235 affected by Ga additions to Ga2Te20As28Se50 and Ga5Te20As25Se50 compositions are probed with positron annihilation spectroscopy in the measuring modes exploring positron lifetimes and Doppler broadening of annihilation line. Occurring of cubic-phase Ga2Se3 droplets with character nanoscale sizes in partially-crystallized Ga2Te20As28Se50 alloy is shown to be associated with agglomeration of intrinsic free-volume voids, this process being enhanced over microcrystalline scale in Ga5Te20As25Se50 alloy. Crystallization changes in the void structure of TAS-235 glass are considered in terms of free-volume evolution under the same principal chemical environment responsible for positron trapping in amorphous and partially crystallized substances.

Optical changes caused by 60Co γ-irradiation are studied in glassy-like As40S60. The observed long-wave shift in the range of fundamental optical absorption edge accompanied by increase in transmittance is explained as a manifestation of complicated nature of radiation-induced structural transformations associated with coordination topological defects and additional shrinkage input from natural physical ageing.