The study of the structural and electrophysical properties of piezoelectrics is an important task for the creation of efficient piezoelectric nanogenerators designed to increase the autonomy of electronic devices. Barium titanate BaTiO3 is one of the promising materials for creating nanogenerators. Special sample preparation is required to study its properties. In this study, the results of studying the electrical properties of an individual BaTiO3 nanowire attached to the substrate surface using atomic force microscopy are presented. The BaTiO3 nanowires are formed by two-stage hydrothermal synthesis using titanium dioxide TiO2 as a precursor and sodium titanate as an intermediate compound. The surface morphology and phase composition of BaTiO3 nanowires are studied using a scanning electron microscope and X-ray diffraction. A technique for fixing an individual BaTiO3 nanowire on a conductive substrate for studying the piezoelectric characteristics using an atomic force microscope (AFM) is presented. The BaTiO3 nanowires obtained have a tetragonal phase with the average length of 14 μm and a diameter of 330 nm. The internal voltage of the nanowire is –0.45 V and the piezoelectric coefficient d33 is 5.2 pm/V. The resulting data confirm the possibility of applying BaTiO3 nanowires in nanogenerators and MEMS devices.

The thermal stability of a CoCrFeNiCu high-entropy alloy (HEA) is studied in the course of prolonged annealing in a temperature range of 873–1273 К for 204 days. The alloy, which is prepared by mechanochemical alloying of metal powders in a planetary-type ball mill for 120 min in an Ar atmosphere, is the substitutional solid solution based on a high-entropy phase with a face-centered cubic structure (fcc). During annealing for 1–3 days, the initial fcc phase decomposes into the copper-enriched fcc1 phase and copper-depleted fcc2 phase, which have close lattice parameters, namely, 3.60 and 3.57 Å, respectively. Throughout the time of annealing, the redistribution of intensities of diffraction reflections of the fcc1 and fcc2 phases occurs, the dynamics and character of which depend on the temperature and time of process. After first three days and to the end of heat treatment, the HEA retains the fcc substitutional solid solution structure, and the lattice parameters of the formed fcc phases retain unchanged with an accuracy of 0.1

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.

Studies of the morphological features and influence of photosensitized WS2, MoS2, and ZnS nanoparticles synthesized by laser ablation and fragmentation in liquid on human fibroblast cells are presented. Microscopy data showed that all types of nanoparticles were spherical in shape, except for WS2 nanoparticles, which were planar. Spherical nanoparticle sizes ranged from 20 to 90 nm, which meets the requirements for theranostics. Cytotoxicity studies demonstrated that MoS2 nanoparticles had high biocompatibility, while other nanoparticle types slowed cell growth, indicating future potential for use in the treatment of various diseases in living organisms.

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

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

— Integrated field-emission devices and integrated circuits (ICs) based on them are a promising direction in microelectronics, which is associated with the use of low-voltage and stable field emitters based on nanomaterials, such as carbon nanotubes (CNTs). The planar design of the field-emission device makes it possible to form CNTs at the end of a thin catalyst film 1–50 nm thick. The paper presents the results of the implementation of an integrated technology for manufacturing planar field-emission diodes with a CNT cathode formed at the end of a thin conducting film. The CNTs are grown by chemical-vapor deposition. A thin film of initially amorphous Co–Nb–N–(O) alloy is used as the growth catalyst. A feature of the technology is the crystallization of Co–Nb–N–(O) alloy during heating in the process of chemical-vapor deposition. As a result, Co nanoparticles are formed on the alloy surface, which catalyze the growth of CNTs. It is shown that this specific feature makes it possible to form CNTs locally, only in open areas of the Co–Nb–N–(O) alloy, for example, at the ends of a thin film. The choice of the Co–Nb–N–(O) alloy is substantiated. The stages of formation of planar field-emission diodes on a silicon substrate are described using standard manufacturing processes. The results of measuring the I – V characteristics of devices are presented. It is shown that the type of I – V characteristics is determined by the field emission characteristic of CNTs. The developed technological method for the local synthesis of CNTs at the ends of topologically formed regions of a thin Co–Nb–N–(O) alloy film can be incorporated into an integrated technology for the formation of planar field-emission devices.

This paper presents the results of facile fabrication of a non-enzymatic glucose sensor by forming a sensing element based on TiO2 nanofilaments using direct ink writing (DIW). The glucose concentration in the solution was determined by changing the resistance of the TiO2 layer. Nanowires (NW) were obtained by hydrothermal synthesis in 10 M sodium alkali solution followed by heat treatment. The surface morphology of obtained samples was studied using scanning electron microscopy. The formation of a sensitive layer was carried out on a 3D printer with a specially designed print head from a suspension based on an aqueous solution of polyvinyl alcohol (PVA) followed by heat treatment in air. The suspension was analyzed for viscosity and contact angle. The sensitive layers were formed on a silicon substrate with a SiO2 surface oxide layer and gold contacts. Layers of TiO2 NW were formed between the contacts. The sensitivity of the sensor to glucose solutions of various concentrations was studied. As a result of the studies, the studied structures showed sensitivity to a glucose solution in the from 1 to 100 mmol.

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.