It was shown for the first time that Ge–Co nanostructures can be formed on a copper substrate by electrochemical deposition. The nanostructures are globules, reaching 1 μm in size and consisting of smaller particles whose size does not exceed 10 nm. They demonstrate a sufficiently high reversible capacity of 850 mA h/g and good stability under long-term cycling.

Germanium-cobalt-indium (Ge-Co-In) nanostructures are a promising material for negative electrodes of lithium- ion batteries aimed for arctic exploitation. Electrochemical impedance spectroscopy was used for a detailed study of the interaction of Ge-Co-In nanostructures with lithium in a temperature range from -35 to +20 degrees C. The discharge capacity at temperatures of 20, 0, -10, -20, and -35 degrees C amounted to 1400, 1228, 1040, 907, and 793 mAh g-1, respectively. The impedance spectra measured at various lithiation degrees were found to differ but insignificantly whereas temperature variation resulted in notable changes in the spectra. A normalized charge transfer resistance for Ge-Co-In nanostructures was significantly (more than an order of magnitude) less than for Ge-In nanowires (obtained by the same method, but without the addition of cobalt salt into the electrolysis solution). It is this difference in charge transfer resistance that can explain the difference in the shapes of the impedance spectra for both objects. Also, in contrast to data for Ge-In nanowires, the dependences of the lithium diffusion coefficient in Ge-Co-In nanostructures on potential had a clearly defined minimum. The lithium diffusion coefficient in Ge-Co-In nanostructures slightly exceeded that in Ge-In nanowires, and the activation energy of lithium diffusion in Ge-Co-In nanostructures was marginally less than in Ge-In nanowires.

Film structures based on Si1–xGex (0 < x < 1) solid solutions are currently obtained by chemical-vapor-deposition methods. For device application of the obtained structures, it is necessary to know the electrical properties of the material synthesized under different conditions. In this work, we carry out galvanomagnetic studies of the electrical conductivity in porous and solid Si1–xGex films, as well as the concentration and mobility of the majority charge carriers in them at a temperature of 30–300 K. It is shown that, as in pure silicon and germanium of comparable porosity, the electrical conductivity in the studied samples can be considered as in a medium with voids. It is established that the type of majority charge carriers in the alloy is determined by the type of silicon substrate used. This is practically important for creating both arms of a thermoelectric converter, which makes the method for producing Si1–xGex(0 < x < 1) alloy promising for device applications, in particular in thermoelectric converters and lithium-ion batteries.

Using photoluminescence and Raman spectroscopy, as well as high-resolution transmission microscopy and X-ray diffraction, germanium nanowires obtained by cathodic deposition from an aqueous solution of germanium dioxide were studied during their annealing by a laser at 720 °C under ambient conditions. It is established that the dynamics of Raman and photoluminescence spectra are related to the oxidation of wires during such annealing. The study showed that vacuum annealing of as-grown nanowires at 600 °C for 30 min suppresses laser high-temperature germanium oxidation. The observed effect is associated with the saturation of vacancies in the surface germanium suboxide with indium atoms used as a catalyst in the formation of nanowires.

A variety of micro‐ and nanocomposite materials based on electrochemically‐acquired porous silicon are produced and evaluated in terms of their applicability to display technology. It is shown that porous silicon provides a versatile and well‐adjustable template for filling with other materials, which can outright change its electrophysical parameters. While, in terms of display applications, porous silicon layers are mostly prominent for their photohiminescence not akin to monocrystalline silicon, this property can be additionally enhanced by employing a variety of electrochemical techniques to form metal deposits of certain shapes.

Continuous and porous films of Si _1-x Ge _x alloys with a germanium content of about 40 % and a thickness of 3–4 μ m formed on single-crystal silicon by electrochemical deposition into the porous silicon matrix with a subsequent rapid thermal annealing at a temperature of 950 ^∘ C have been investigated by the Raman scattering spectroscopy and scanning electron microscopy methods. Based on the spectra in the Stokes and anti-Stokes frequency bands with the use of the Boltzmann statistics and the Fourier thermal conductivity law, the film thermal conductivity coefficients have been determined; their values are 7–9 and 3–6 W/(m K) for the continuous and porous films, respectively. The low thermal conductivity of the porous film is explained by an additional phonon scattering at a developed surface of pores. The possibility of application of such films in thermoelectric converters is provided by the simplicity and scalability of the procedure of alloy producing and its low thermal conductivity

Two new electrochemical systems have been developed for sodium-ion batteries with a positive electrode based on manganese-doped sodium iron phosphate (NaFe0.5Mn0.5PO4) and a negative electrode based on a CoGe2P0.1 nanostructure, as well as with a positive electrode based on iron-doped sodium vanadophosphate (Na3V1.9Fe0.1(PO4)3) and a negative electrode based on a CoGe2P0.1 nanostructure. The results of cycling of battery models showed that the energy density of the NaFe0.5Mn0.5PO4/CoGe2P0.1 and Na3V1.9Fe0.1(PO4)3/CoGe2P0.1 electrochemical systems is 165 and 167 W h/kg, respectively.

A novel approach was developed to locally fabricate planar lithium-ion batteries using composite electrode materials. The method involved electrophoretic deposition to create a composite cathode material comprising NCA and Super C45, while the anode was formed through localized electrochemical deposition of germanium nanofibers. This technique successfully formed planar batteries with heterogeneous composite electrodes on a single plane, offering advantages such as efficient ion transport, minimized electrode polarization, and enhanced electrochemical performance. The integration of electrochemical and electrophoretic deposition methods allowed for precise control of layer composition and deposition parameters, optimizing the properties of planar batteries in terms of specific capacitance and electrical conductivity. The study also focused on laser engraving topology and optimized modes for planar battery structures, enabling the integration of multiple processes in a single manufacturing cycle. Capacitive characteristics were assessed using specialized polypropylene tooling, and the planar battery prototypes demonstrated comparable capacity (4 mu Ah) to existing commercial alternatives.

Arrays of titanium dioxide (TiO 2 ) nanotubes with different chemical compositions have been synthesized; their structural properties have been studied, and the characteristics of spin centers (defects) have been determined. All samples have appeared to contain carbon. It has been established that the main type of spin centers in TiO 2 nanotubes are dangling carbon bonds, and their concentration correlates with the carbon content in the obtained structures. Under illumination, a reversible increase in the concentration of defects occurs, which is caused by their photoinduced recharging in the process of impurity absorption. This process is accompanied by an increase in the concentration of photoexcited electrons in the conduction band. The originality and novelty of the work are determined by the development of a method for controlling the density of defects and, accordingly, the concentration of photoinduced electrons by thermal treatment of samples under various conditions. The results open up new possibilities for the development of photocatalysts based on titanium dioxide nanotubes with a controlled electron concentration in the conduction band that function in the visible range of the spectrum.

Сплошные и пористые плёнки сплавов Si1-xGex с содержанием германия около 40 % и толщиной 3-4 мкм, сформированные на монокристаллическом кремнии методом электрохимического осаждения германия в матрицу пористого кремния с последующим быстрым термическим отжигом при температуре 950 °C, исследованы методами спектроскопии комбинационного рассеяния света (КРС), оптической спектроскопии и сканирующей электронной микроскопии. На основе спектров, снятых в стоксовой и антистоксовой областях частот с использованием статистики Больцмана и закона теплопроводности Фурье, определены коэффициенты теплопроводности плёнок, которые составляют 7-9 и 3-6 Вт / (м ⋅ К) для сплошной и пористой плёнок соответственно. Низкая теплопроводность пористой плёнки объясняется дополнительнымфононным рассеянием на развитой поверхности пор. Перспективность применения таких плёнок в термоэлектрических преобразователях обеспечивается простотой и масштабируемостью способа изготовления сплава, а также его низкой теплопроводностью. Solid and porous films of the Si 1-xGex alloys with a germanium content of about 40% and a thickness of 3-4 μm, formed on single-crystal silicon by electrochemical deposition of germanium into a porous silicon matrix followed by rapid thermal annealing at a temperature of 950 °C, are studied by Raman spectroscopy, optical spectroscopy, and scanning electron microscopy. Based on the Raman spectra taken in the Stokes and anti-Stokes frequency regions, using Boltzmann statistics and the Fourier thermal conductivity law, the thermal conductivity of the films is determined, which is found to be 7-9 and 3-6 W/(m×K) for a continuous and porous film, respectively. The low thermal conductivity of the porous film is explained by additional phonon scattering from the developed pore surface. The prospect of using such films in thermoelectric converters is ensured by the simplicity and scalability of the method for manufacturing the alloy, as well as its low thermal conductivity.

Continuous and porous films of Si(1-x)Ge(x )alloys with a germanium content of about40%and a thickness of 3-4 mu m formed on single-crystal silicon by electrochemical deposition in to the porous silicon matrix with a subsequent rapid thermal annealing at a temperature of 950(degrees)Chave been investigated by the Raman scattering spectroscopy and scanning electron microscopy methods. Based on the spectra in the Stokes and anti-Stokes frequency bands with the use of the Boltzmann statistics and the Fourier thermal conductivity law, the film thermal conductivity coefficients have been determined; their values are 7-9 and 3-6 W/(m K) for the continuous and porous films, respectively. The low thermal conductivity of the porous film is explained by an additional phonon scattering at a developed surface of pores. The possibility of application of such films in thermoelectric converters is provided by the simplicity and scalability of the procedure of alloy producing and its low thermal conductivity

Basic studies in the application of germanium nanowires obtained by electrolysis of aqueous solutions, as well as germanium phosphide nanorods, as negative electrodes for lithium-ion and sodium-ion batteries carried out in the Frumkin Institute of Physical Chemistry and Electrochemistry, RAS, are concisely reviewed.

Cobalt-based catalysts are one of the possible candidates for catalysts that accelerate the decomposition of water to produce energy. In this work, the one-dimension Ge-Co nanostructures have been prepared by electrochemical deposition in a three-electrode cell. The samples have been annealed in atmosphere at various temperature (300 degrees C, 450 degrees C, 600 degrees C). Effect of thermal annealing on the composition of Ge-Co nanostructure has been studied. The morphology of the obtained Ge-Co nanostructures has been investigated using scanning electron microscopy The method of X-ray diffraction analysis has been used to investigate composition changes of Ge-Co. Diffractograms show the presence of Co2GeO4 catalyst at an annealing temperature of 600 degrees C. The sample with this annealing temperature shows the best properties as oxygen evolution catalyst.

The regularities of composition changes of silicon/germanium alloy thin films formed on a monocrystalline silicon substrate by electrochemical deposition of germanium into a porous silicon matrix with subsequent rapid thermal annealing (RTA) at a temperature of 750–950°C are studied. An analysis of the samples by Raman spectroscopy showed that an increase of RTA temperature leads to a decrease in the germanium concentration in the formed film. A decrease of the RTA duration at a given temperature makes it possible to obtain films with a higher concentration of germanium and to control the composition of thin silicon/germanium alloy films formed by changing the temperature and duration of RTA. The obtained results on controlling the composition of silicon/germanium alloy films can be used to create functional electronic devices, thermoelectric power converters, and optoelectronic devices.

The hard x-ray copper K (alpha) source formed by the interaction of a high intensity laser pulse with flat and thicket sub-micron structured copper targets is thoroughly characterized. It is shown that the flux of quanta can be increased up to several times using the structured target instead of the flat one. The maximal conversion efficiency into K (alpha) reaches 1.4 x 10(-4) corresponding to >10(9) photons with a high contrast ratio over the bremsstrahlung radiation at the peak intensity similar to 10(18) W cm(-2). The efficient use of the thicket target at higher intensity (2 x 10(18) W cm(-2)) is limited by temporal contrast of the laser pulse and the few-fold lowered damage threshold of the modified target. Measurements of the x-ray source size revealed that the lateral coherence is similar both for the flat and thicket target. The estimated source size of similar to 15 mu m makes it suitable for the x-ray phase contrast imaging with reasonable geometry and short time object exposure. A simple concept of the image acquisition correction is proposed in order to account for the x-ray source lateral shifts, which is based on measurements in each shot instead of long exposure. Image post-processing allowed us to enhance source lateral coherence and retrieve phase contrast effects when the x-ray source shifts exceed its size.

It is concluded that oxidation of porous silicon in an air atmosphere at 300 ° C or in an aqueous solution of nitric acid (50 vol.%) can drastically improve the filling of pores by indium during its subsequent electrochemical deposition. Due to the oxidation of the porous skeleton’s topmost areas, the maximum concentration of indium is shifted from the surface deeper into the pore channels. This effect is especially apparent in the case of oxidation via nitric acid, whereat the maximum relative concentration of indium inside the pores is achieved.

We investigated the effect of focusing sub-nanosecond laser radiation with varied fluence onto the surface of different flat and nanostructured targets utilized in ultra-high intensity laser-plasma experiments. Thus, we modeled the action of the prepulse, referred to as an amplified spontaneous emission pedestal, typically present for a relativistic (with peak intensity over 10(18) W cm(-2)) laser pulse with naturally limited contrast. The suppressed melting threshold was detected for the sub-wavelength scale structured material. Local melting leading to distortion of initial structures was detected at a fluence of similar to 0.2 J cm(-2) and below, or 3-5 times lower compared to the flat substrate melting threshold. It is also demonstrated that the threshold lowering is dependent on the production method of the structures, which may be attributed to increased absorption and suppressed heat transfer into the bulk.