Ge nanoporous layers formed by implantation of monocrystalline c-Ge substrates with In+ ions at an energy of E = 40 keV and doses of D from 1.8 × 1016 to 7.5 × 1016 ion/cm2 were studied by scanning electron microscopy (SEM) and Raman scattering. The obtained SEM micrographs made it possible to evaluate the morphology of the sample surface and the porosity of the layers. Based on the Raman data, it was found that the formed nanoporous layers are amorphous. The excitation of Raman scattering by a helium-neon laser with an intensity of more than 1500 W/cm2 leads to heating and subsequent local crystallization of the irradiated regions in the nanoporous layers. According to the results of the Raman studies, the volume fraction of the crystalline phase in the nanoporous layer was estimated, to be the maximum for the sample formed with D = 5.6 × 1016 ion/cm2, which correlates with the maximum porosity.

In this work, thin films of hafnium oxide HfOx obtained by electron beam deposition were crystallized by thermal annealing in air atmosphere. The relationship between the structural changes occurring as a result of annealing and the electrical properties of the films was determined. It was found that the formation of nanocrystals with a monoclinic structure in the studied films, occurring at annealing temperatures of 500°C and higher, is accompanied by a decrease in their specific conductivity by more than 6 times, which can be associated with a decrease in the number of oxygen vacancies as a result of structure ordering. It was also shown that the specific conductivity of all HfOx films (pristine and annealed at different temperatures) has a strong dependence on temperature, described by the activation law with an activation energy from 0.86 to 0.93 eV. The obtained data can be used to improve the characteristics of memristive systems and other electronic devices based on hafnium oxide layers.

Nanocomposites based on anodic titanium oxide nanotubes with copper oxide nanoparticles were formed and their structural, optical, and electrophysical properties were studied. Defects in the structure of the samples were identified by electron paramagnetic resonance and it was shown that, as a result of copper oxide deposition, CuO nanoparticles were formed on the surface of nanotubes. It was found that the conductivity of the structure decreases by several orders of magnitude with an increase in the number of deposition cycles. It was shown that this effect could be associated with the formation of TiO2/CuO heterojunctions on the nanotube surface. It was shown for the first time that an increase in the content of copper oxide in TiO2/CuxO nanocomposites was accompanied by a decrease in conductivity and an increase in the number of defects.

Films of hafnium oxide HfOx with a thickness of about 40 nm were obtained by electron beam sputtering at di erent oxygen ow rates in the chamber. The electrophysical properties of lms in air and vacuum were studied. It is shown that the temperature dependences of lm conductivity, measured in vacuum inthe temperature range from 20 to 180 ◦C, have an activation character with an activation energy of 0.82 ±0.02 eV. It has been suggested that charge transfer in the resulting lms is determined by the activation of electrons into the conduction band from the donor level associated with oxygen vacancies. It was found that the conductivity of lms in air changes greatly with varying oxygen ow, while in vacuum the conductivity is practically independent of the oxygen ow. This indicates signi cant di erences in the surface properties of lms obtained at di erent oxygen ows in the chamber during the deposition process.

In this work, the features of In particle electrodeposition from aqueous solutions were shown. The dependence of the morphology and geometric characteristics of the In particles on the parameters of the electrodeposition process were obtained. For each case, a scanning electron microscopy image was presented, which was used to analyze the morphology and estimate the average size of indium particles. A study was carried out to determine the type of nucleation of In particles during deposition in the potentiostatic mode depending on the applied potential and the concentration of In in the solution. It has been established that at potentials of − 1 V and − 1.1 V, as well as an InCl3 concentration of 0.01 M and 0.02 M in the solution, the nucleation of In occurs by the instantaneous type. When studying the process of In deposition in the galvanostatic mode, it was shown that with an increase in the InCl3 concentration in solution from 0.002 to 0.02 M, the average particle size increased almost linearly, while their number per unit area decreased exponentially. The unique properties of particles due to surface and quantum-dimensional effects depend directly on their size. In addition, if the particles are used as seed particles in the growth process of one-dimensional semiconductor structures, the size of indium particles affects the diameter of one-dimensional structures. Therefore, it is important to obtain indium particles of certain sizes.

We theoretically investigate phonon and thermal properties in germanium nanowires with square cross-sections ranging from 2.26 to 27.72 nm. Using a face-centered cubic cell model for lattice vibrations and the Boltzmann transport equation approach, we find that the thermal conductivity of Ge nanowires is 3 to 20 times lower than in bulk c-Ge, depending on the roughness of the nanowire surfaces. This significant decrease in lattice thermal conductivity results from the interplay between two effects: the redistribution of phonon energy spectra due to spatial confinement and phonon boundary scattering. We calculate the temperature distribution in a nanometer-thick porous germanium film with a thermal conductivity of 3.5 W/(m K), typical for rough Ge nanowires. Our results indicate the potential for localized heating in specific regions, reaching temperatures up to 950 K. This finding aligns well with previous experimental estimations made using Raman spectroscopy.

Changes in the strength of a one-dimensional elementary composite material−microplastic based on epoxide resin and complex aramid thread treated with graphene oxide are reported. The maximum increase in the strength of the microplastic was 13.36

Nanocomposites based on anodic titanium oxide nanotubes with copper oxide nanoparticles were formed and their structural, optical, and electrophysical properties were studied. Defects in the structure of the samples were identified by electron paramagnetic resonance and it was shown that, as a result of copper oxide deposition, CuO nanoparticles were formed on the surface of nanotubes. It was found that the conductivity of the structure decreases by several orders of magnitude with an increase in the number of deposition cycles. It was shown that this effect could be associated with the formation of TiO2 /CuO heterojunctions on the nanotube surface. It was shown for the first time that an increase in the content of copper oxide in TiO2/CuxO nanocomposites was accompanied by a decrease in conductivity and an increase in the number of defects.

The formation of polyene-polyyne-based nanocomposites by dehydrohalogenation of the drop-cast-deposited polyvinylidene fluoride, assessment and ion-induced tailoring of their gas sensing properties are reported. The investigated structure was analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy and Fourier-transform infrared spectroscopy, revealing the thickness-dependent incomplete dehydrofluorination of the structure and its porosity induced by KOH treatment. The polyene-polyyne structures modified by low-energy Ar+ were studied by SEM and Raman spectroscopy, which showed the morphology variation, the shortening of chains and the graphitization of samples. The resistive gas sensing properties of the samples were analyzed at room temperature, revealing selective sensing of ammonia vapor by non-irradiated sample and the enhancement of the sensing properties for ethanol and water vapor after ion irradiation. With the ion dose enlargement, the change in the sensing response from electrical conductivity increase to decrease was observed for ammonia and ethanol, allowing us to discuss the origin and tunability of the sensing mechanism of the samples.

The films fabricated by heat treatment at 600–800°C of a material based on sp carbon synthesized by polyvinylidene fluoride dehydrofluorination are studied. The structure of the films is studied by scanning electron microscopy, X-ray diffraction, infrared spectroscopy, and Raman spectroscopy. For the electron emission of the films, the turn-on field is 0.3–1.5 V/μm. The influence of the structure of the polyene and graphite phases having formed upon annealing on the emission characteristics of the material is considered. The emission is found to be caused by field emission and thermionic mechanisms.

We report on the formation of the field-effect transistor based on a polyyne–polyene structure. Polyvinylidene chloride (PVDC) drop casting and its subsequent dehydrochlorination in KOH solution allowed for the formation of porous polyyne–polyene material, which was analyzed via transmission electron microscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy, revealing the presence of sp- and sp2-hybridized chained fragments in the structure. The polyyne–polyene-based field-effect transistor showed a transconductance of 3.2 nA/V and a threshold voltage of −0.3 V. The obtained results indicate that polyyne–polyene-based transistors can be used as discrete elements of molecular electronics and that subsequent studies can be aimed toward the development of selective polyyne–polyene-based gas sensors with tunable sensitivity.

Resistive sensing responses of the thin films obtained by dehydrohalogenation of polyvinylidene chloride (PVDC) and polyvinylidene chloride–polyvinyl chloride (PVDC-PVC) copolymer were investigated. The structure of the samples was studied by transmission electron microscopy, Fourier-transform infrared spectroscopy and Raman spectroscopy. The analyses demonstrate the formation of a porous structure based on polyyne–polyene chains. The formation of a foam-like oxidized sp-rich structure was observed for the samples obtained via the chemical treatment of the PVDC. However, a loose film with a developed structure and a lower fraction of sp-hybridized carbon was observed for KOH-treated PVDC-PVC. The resistive sensing responses of both of the dehydrohalogenated structures were measured for various concentrations of acetone, acetic acid, ammonia hydroxide, methanol, ethanol, benzene and water. The interplay between the efficiency of the dehydrohalogenation of the films, their structure and sensing selectivity is discussed.

Porous Ge layers were fabricated by implanting Cu+ ions of various acceleration energies into c-Ge substrate. This made it possible to form amorphous porous Ge layers of thicknesses from 18.6 to 50.5 nm. The distribution depth profiles of implanted Cu+ ions in Ge were simulated by SRIM-2013 program. The formed layers were studied by Raman spectroscopy. The excitation was carried out by a laser with a wavelength of 488 nm, which has a small penetration depth of similar to 20 nm. In the Raman spectra, there is a possibility to distinguish the contribution from the amorphous Ge film, the crystalline c-Ge substrate, and Ge nanocrystals, which appear under intense laser excitation due to local crystallization. The decomposition of the spectra into individual components makes it possible to subtract the contribution of the substrate and estimate the crystalline volume fraction in the layers. The results obtained confirm the hypothesis of low thermal conductivity of the porous layer, due to which local crystallization occurs.

This work demonstrates the possibility of electrochemical formation of Ge-Sn-O nanostructures from aqueous solutions containing germanium dioxide and tin (II) chloride at room temperature without prior deposition of fusible metal particles. This method does not require complex technological equipment, expensive and toxic germanium precursors, or binding additives. These advantages will make it possible to obtain such structures on an industrial scale (e.g., using roll-to-roll technology). The structural properties and composition of Ge-Sn-O nanostructures were studied by means of scanning electron microscopy and X-ray photoelectron spectroscopy. The samples obtained represent a filamentary structure with a diameter of about 10 nm. Electrochemical studies of Ge-Sn-O nanostructures were studied by cyclic voltammetry and galvanostatic cycling. Studies of the processes of lithium-ion insertion/extraction showed that the obtained structures have a practical discharge capacity at the first cycle ~625 mAh/g (specific capacity ca. 625 mAh/g). However, the discharge capacity by cycle 30 was no more than 40% of the initial capacity. The obtained results would benefit the further design of Ge-Sn-O nanostructures formed by simple electrochemical deposition.

Nanocomposites based on anodic titanium oxide nanotubes with copper oxide nanoparticles were formed and their structural, optical, and electrophysical properties were studied. Defects in the structure of the samples were identified by electron paramagnetic resonance and it was shown that, as a result of copper oxide deposition, CuO nanoparticles were formed on the surface of nanotubes. It was found that the conductivity of the structure decreases by several orders of magnitude with an increase in the number of deposition cycles. It was shown that this effect could be associated with the formation of TiO 2 /CuO heterojunctions on the nanotube surface. It was shown for the first time that an increase in the content of copper oxide in TiO 2 /Cu x O nanocomposites was accompanied by a decrease in conductivity and an increase in the number of defects. Keywords: titanium oxide, nanotubes, nanocomposites, copper oxide nanoparticles, defects, conductivity.

To overcome the low conductance issue of cobalt oxide nanofibers, we have synthesized cobalt oxide-based nanofibers with zinc (Co3O4/Zn) by the method of electrospinning. The structure of materials in this work were characterized extensively using X-ray diffraction, an X-ray fluorescence method, electron microscopy, and infrared and Raman spectroscopy. Nanofibers are shown to have a diameter of approximately 150 nm and consist of crystallites with an average size of about 20 nm. It has been found that the adding of zinc can significantly increase the conductivity of nanofibers: at a zinc concentration of about 15%, the conductivity increases by more than 4 orders of magnitude compared to cobalt oxide nanofibers without zinc and remains of p-type. We have shown that composite consists of ZnxCo3-xO4 and ZnO structures. Additionally, electron paramagnetic resonance (EPR) spectroscopy was conducted to identify the paramagnetic defects in the composites. Findings from the EPR spectroscopy were combined with the aforementioned characterization techniques to illuminate the mechanism of conductivity enhancement. The correlation between the concentration of paramagnetic cobalt atoms in an octahedral environment and the conductivity of Co3O4/ Zn composites indicates that the change in conductivity is associated with a change in the concentration of acceptor levels in the ZnxCo3-xO4 structure. Our results suggest that synthesis of nanofibers with zinc by electrospinning could be a promising method to construct high conductivity cobalt oxide-based nanofibers for environmental applications.

Porous Ge layers consisting of nanowires were formed by low-energy high-dose implantation of monocrystalline c-Ge substrate with Ag+ and Cu+ ions. The obtained layers were studied by Raman spectroscopy using solid-state and He-Ne exciting lasers with wavelength of 532 and 633 nm, respectively. The crystalline volume fraction and local temperature of porous layers at the surface sites of laser probing were determined. To interpret the change in the shape of the spectra under the action of laser radiation, deconvolution into amorphous and nanocrystalline components was carried out. Analysis of the spectral line shape made it possible to estimate the crystalline and amorphous volume fractions. The quantum confinement model for Ge nanocrystallites was taken into account for accurate estimations of volume fractions. These estimates showed that the implanted amorphous layers of all samples were locally crystallized with a solid-state laser. He-Ne laser excitation resulted in partial crystallization only for layers obtained by Cu+ ion implantation. The measured ratio of the Stokes to anti-Stokes components demonstrated that the porous layers obtained by implanting Ag+ ion were not heated by a He-Ne laser and according to the analysis of spectral lines, the crystalline volume fraction did not appear in these layers during probing. The results obtained are explained by the difference in the penetration depth for various samples of the exciting radiation.

The effect of ultraviolet radiation on the strength characteristics and structure of copolymeric para-aramid fiber was studied. A sample of the fiber produced under industrial conditions at the Termoteks plant was investigated. A suspension of Taunit carbon nanotubes was used to modify the fibers. Increased strength characteristics in the fiber and reduced degradation under ultraviolet exposure were obtained as a result of the treatment.

Titania is very famous photocatalyst for decomposition of organic pollutants. Its photocatalytic properties significantly depend on the morphology and chemical composition of the samples. Herein, the TiO2 nanotubes/CuxO nanoheterostructures have been synthesized and the effect of heat treatment performed in molecular atmospheres of air and argon on their photoelectrochemical and photocatalytic properties has been studied. The prepared samples have a higher reaction rate constant compared to TiO2 nanotubes in the decomposition reaction of methylene blue molecules. It is established that in argon treated nanoheterostructures, the copper oxide is present in two phases, CuO and Cu2O, while in air treated ones there is only CuO. In the TiO2 nanotubes/CuxO samples, Cu2+ ions and molecular O2− radicals were detected while in TiO2 nanotubes only carbon dangling bond defects are present. The dynamics of O2− radicals under illumination are discussed. It was shown that the TiO2 nanotubes do not exhibit photocatalytic activity under visible light. The mechanism of the photocatalytic reaction on the surface of the TiO2 nanotubes/CuxO samples was proposed. It is assumed that a photocatalytic decomposition of organic molecules under visible light at the surface of the nanoheterostructures under investigation is realized mainly by the reaction of these molecules with photogenerated O2− radicals. The results obtained are completely original and indicate the high promise of the prepared photocatalysts.

In this work, we propose a new, previously unpresented in the literature, approach to the formation of Si1-xGex films. This approach includes electrochemical processes of the formation of porous silicon, electrochemical deposition of low-melting metals and Ge. Post-heat treatment is made possible to synthesize film structures based on Si1-xGex solid solutions. Using this approach an alloy of the composition Si0.4Ge0.6 has been obtained at a lower formation temperature than predicted by the phase diagram for the Si-Ge system.