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Herein, we have developed a new efficient flexible hydrophobic thermoelectric (TE) material with increased thermal stability and mechanical strength for green energy production. The 8 µm thick flexible nanocellulose (NC) substrate was obtained from stalks of common reed by TEMPO-mediated oxidation. It has a high crystallinity index of 88 % and the amount of coherent scattering of nanocrystals in the range from 2 to 3 nm. A CuI film with a thickness of 4.3 μm was deposited on the NC substrate by the Successive Ionic Layer Adsorption and Reaction (SILAR), and thus a CuI/NC thin film thermoelectric material was obtained. The average size of the CuI coherent scattering regions is 25 nm. CuI nanocrystals contain dislocations (1.6x1015 lines/m²) and tensile microstrains of 6x10³ arb. units. The optical band gap Eg for direct allowed transitions in the CuI film is about 3.0 eV. The high hydrophobicity of the CuI/NC material is a useful feature for applications in humid environments. The CuI/NC material contains the same number of copper and iodine atoms. In addition, a small amount of sulfur (<1 at.%) is present in the copper iodide film, which increases the thermopower coefficient of CuI/NC to 6.7 μW/(m·K²) at T = 340 K. Its positive Seebeck coefficient S = 108 μV/K confirmed the p-type conductivity of CuI. The change in the resistivity upon initial heating and subsequent cooling demonstrated the electrical conductivity crossover typical of films of nanocrystalline degenerate semiconductor CuI. A CuI/NC sample in the form of a 3 cm x 1 cm strip was tested as a planar thin film TE element. The output power density of a CuI/NC TE element 0.123 W/m² was experimentally recorded at a difference between its hot and cold edges of 40 K. [ABSTRACT FROM AUTHOR]

The temperature dependence of the resistance of chromium films obtained by the thermal deposition on a substrate at room temperature was studied. It is shown that the most probable crystallite size in as-deposited films is 9 nm and increases by about 15% after the first annealing. According to the results of resistive studies, the structure formed after the first heating is stable and changes slightly during thermal cycling. It has been found that up to a temperature of approximately 200 °C, the temperature coefficient of resistance of the samples is negative and amounts to approximately −2 · 10−4 K−1. With a further increase in temperature, the temperature coefficient of resistance becomes positive, but remains significantly lower than the value corresponding to chromium in the bulk state. The observed effects are explained by the nanocrystalline structure of the samples. [ABSTRACT FROM AUTHOR]

The β → α phase transition and diffusion of the hydrogen in nanocrystalline vanadium films were investigated. Films were deposited onto the glass substrate at the temperature 673 K and at room temperature. Transmission electron microscopy investigations of the structure of films showed that the averaged sizes of vanadium crystallites were 7 and 4 nm, respectively. The derivative of the electrical resistance of the saturated film revealed the broad β → α phase transition about 390 K. The diffusion coefficient of the hydrogen was obtained from the approximation of the time dependence of the increase of the electrical resistance of the non-saturated part of the film by an analytical expression. Values of the diffusion coefficient revealed the strong dependence on the concentration of the hydrogen. At small concentration of the hydrogen, the diffusion coefficient was equal to that in the bulk vanadium. At large concentrations of the hydrogen (above 20 at. %), the diffusion coefficient decreases by a thousand times. The activation energy of diffusion, calculated for samples with the large concentration of the hydrogen, is equal to (44.8 ± 0.8) kJ/mol [(0.464 ± 0.008) eV]. [ABSTRACT FROM AUTHOR]

Maps of spatial distributions of Ti, Al, and C on two surfaces of the Ti3AlC2 hexagonal phase (the so-called MAX phase) with inclusions of the TiC phase and Al2O3 were obtained by means of the energy-dispersive X-ray spectroscopy. Volume fractions of phases were 0.848, 0.107, and 0.045, respectively. The sample was cut from the synthesized tablet. One of the analyzed surfaces of the sample was the free outer surface of the tablet (surface 1), and another surface was the cut (surface 2). Histograms of the concentration distributions of elements were plotted. For both surfaces, histograms of all elements have Gaussian forms with mean values of about their stoichiometric concentrations in Ti3AlC2 and TiC phases. Histograms for the carbon have maxima at 34–36 at. %, which is close to the stoichiometric content of the carbon in the Ti3AlC2 MAX phase (33 at. %), and at about 50 at. % that corresponds to the stoichiometric concentration of the carbon in the TiC phase. However, Gaussian standard deviations from these mean values are large (up to 7 at. %), which proves the existence of th vacancies and interstitials of the carbon in phases. The histogram for the aluminum on surface 1 has an additional distribution near zero value of the concentration, and the histogram for carbon on surface 2 has an additional distribution near 27.7 at. %. Both found particularities can be explained by supposing that the outer surface of the original tablet cools down more rapidly than its inner parts. [ABSTRACT FROM AUTHOR]

From a limited tin solution-melt in the temperature range of 950-700°C, Si--Si1-xGex--(Si1-xGex)1-z(Al1-yGayAs)z--Si1-xGex--(Si1-xGex)1-z(Al1-yGayAs)z structures on Si h111i substrates were grown by liquid-phase epitaxy in a single technological cycle. Using a scanning electron microscope, the layered composition of the grown films was determined. X-ray diffraction studies of the structure showed the dependence of the crystalline perfection of the film on the technological growth regime. The optimum mode of forced cooling rate (1 deg/minute) was established during cultivation. Some electrophysical and photoelectric properties of Si--Si1-xGex--(Si1-xGex)1-z(Al1-yGayAs)z-- Si1-xGex--(Si1-xGex)1-z(Al1-yGayAs)z structures were determined. [ABSTRACT FROM AUTHOR]

The structure and processes of mass, charge and heat transfer are investigated in an equiatomic Fe–Ni composite fabricated by electroconsolidation using the spark plasma sintering (SPS) technology. The system contains regions of almost pure Fe and Ni, separated by areas with variable concentration of components, formed in consequence of the interdiffusion in the electroconsolidation process. The interdiffusion coefficient of the Fe–Ni system has been revealed to be significantly higher than that of an alloy of a similar composition at the same temperature, which is likely the result of the employed SPS technology and the enhanced diffusion along the grain boundaries. The concentration dependence of the interdiffusion coefficient passes through a maximum at a Ni concentration of ∼ 70 at.%. The electrical and thermal conductivity of the studied system is significantly higher than that of an alloy of the same composition. The temperature dependence of the resistivity of the sample in the range 5–300 K is due to the scattering of electrons by defects and phonons, and the scattering of electrons by phonons fits well to the Bloch–Grüneisen–Wilson relation. The boundaries of the conductivity of the investigated composite correspond to the Hashin–Shtrikman boundaries for a three-phase system, if Fe, Ni and the FeNi alloy are selected as phases. [ABSTRACT FROM AUTHOR]

Indium-doped zinc oxide (ZnO:In) thin films were deposited onto cotton (Ct) and polyester (PET) fabrics via Successive Ionic Layer Adsorption and Reaction (SILAR) method for the purpose of developing comfortable to wear, nontoxic, lightweight, and air-permeable textile. Thus, we obtained materials with hierarchical micro- and nanoscale roughness ZnO:In/Ct and ZnO:In/PET, respectively. The obtained ZnO:In films have a single-phase nanograined polycrystalline wurtzite hexagonal structure. It has been shown that the inherent cotton hydrophilicity provides wettability of ZnO:In/Ct fabric both before and after vacuum annealing. On the contrary, the ZnO:In/PET fabric is hydrophobic, its water contact angle CA equals 140°. It turned out that it is possible to impart superhydrophobic properties to the ZnO:In/PET fabric without any additional impregnation layer by means of post-growth vacuum annealing at 200 °C for 1 or 2 h. The superhydrophobiсity of this fabric was confirmed via both static and dynamic measurements of CA = 160° and contact angle hysteresis CAH = 10°, respectively. The Cassie-Baxter wetting state for the annealed ZnO:In/PET fabric is identified through a water-drop evaporation technique. Upon exposure to ultraviolet (UV) radiation (26 W, wavelengths in the 315-400 nm range) for 60 min, the vacuum annealed ZnO:In/PET fabrics are transformed from superhydrophobic to hydrophobic, their СAs reduced from 160° to ~ 130° and returned after 9 days of storage in the dark. Thus, we obtained a superhydrophobic fabric that remains non-wettable under operating conditions in sunlight. [ABSTRACT FROM AUTHOR]

The paper presents a study of interdiffusion processes in a binary Fe-Ni system (obtained by elec-troconsolidation of nickel and iron powders) by X-ray energy dispersive spectroscopy. Well-separated regions of almost pure iron and nickel have been discovered. The content of nickel, estimated from the concentration dependence of the interdiffusion coefficient, which determines the kinetics of the ho-mogenization process of the electroconsolidated Fe-Ni composite sample, was ≈ 70 at.%. The value of the interdiffusion coefficient of the electroconsolidated Fe-Ni composite is significantly higher than that of the alloy of similar composition which probably results from the effect of spark plasma sintering technology (pressure and current along the same direction during consolidation) but also from a significant contribution of diffusion with mass transfer along the particle boundaries in the composite. [ABSTRACT FROM AUTHOR]

In this work, we study a suitability for protection against terrestrial ultraviolet part of the solar spectrum of undoped and doped by indium zinc oxide thin nanostructured films, ZnO and ZnO:In, respectively, and cuprous iodide (CuI) films obtained via Successive Ionic Layer Adsorption and Reaction (SILAR) techniques on the lightweight low cost poly(ethylene terephthalate) (PET) flexible substrates. The film morphology is observed by scanning electron microscopy (SEM). Chemical compositions of the films are investigated by X-ray fluorescence (XRF) microanalysis. To research crystal structure we used X-ray diffraction (XRD) method. The UV-protection ability of the nanostructured thin films, PET tapes and samples consisting of the PET substrates and the films deposited on them by the SILAR method has been evaluated on the base of their optical properties in accordance with an international standard ISO 2443:2012(E) “Determination of sunscreen UVA photoprotection in vitro”. According to the research, nanostructured ZnO, ZnO:In and CuI thin films made by the cheap, affordable, and suitable for mass production SILAR method on thin flexible cheap PET substrates have been proposed as a new material for UV-shielding applications. In accordance with an international standard ISO 2443:2012(E), UV-protection ability of the samples consisting of the PET substrates and the films deposited on them by the SILAR method fits the category “excellent” (50+). The best low cost flexible and lightweight UV shielding material turned out to be that consisted from ZnO:In film and PET substrate, the sun protection factor of which equals 157. [ABSTRACT FROM AUTHOR]

In this work, we investigated the effect of glow-discharge H2+ plasma treatment on ZnO layers deposited on fluorine doped tin oxide (FTO) glass substrates through low temperature aqueous solution growth, namely, via a pulsed electrochemical deposition and by successive ionic layer adsorption and reaction (SILAR) technique. It is shown that the crystal structure, surface morphology, chemical composition and optical properties obtain some destructive changes after plasma processing due to the creation of oxygen vacancies Vo and H-related defects, and additionally, because of the zinc oxide etching by the glowdischarge H2+ plasma through reduction of zinc oxide and evaporation of Zn from the surface. Nevertheless, our investigations show quite good stability of the ZnO layers to the plasma-induced radiation and chemical impacts under high total H2+ fluence received by every ZnO/FTO sample ~ 8·1018 cm –2. [ABSTRACT FROM AUTHOR]

Copyright of Metallophysics & Advanced Technologies / Metallofizika i Novejsie Tehnologii is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The investigations of effect of long-wave (UVA) and short-wave (UVC) ultraviolet light of extraterrestrial solar irradiance on the nanostructured zinc oxide arrays, which were grown by pulsed electrodeposition, as well as on the ZnO and ZnO:In films produced by Successive Ionic Layer Adsorption and Reaction technique (SILAR) confirmed their suitability as UVA-active photosensitive materials. The crystal structure, surface morphology, chemical composition and optical properties found no obvious significant destructive changes after UVC irradiation. However, we detected some irreversible changes in the nature of point defects under the influence of UVC, which affect the ZnO and ZnO:In resistivity, activation energy, photosensitivity and thermoelectrical properties. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The results of the study of melting of Bi–Sn and Pb–Sn polycrystalline layered film systems with the thickness of 200–400 nm on a substrate with temperature gradient are given. Multilayer (each layer is of 10–20 nm) and bilayer films (layers are of 100–200 nm) of the same total thickness have been investigated. Broadening of the melting range in all films and lowering of melting point in multilayer samples compared to the bilayer ones have been observed. The observed phenomena are discussed within existing thermodynamic concepts in consideration of interfacial energy of contacting layers of components and energy of grain boundaries in polycrystalline films [ABSTRACT FROM AUTHOR]