The use of graphene in electronics requires both an experimental study of the formation of high-quality low-resistance contacts and a deeper understanding of the mechanisms of electron carrier transport in graphene sheets and in the vicinity of metal / graphene interface. In this work, we studied the charge carrier transport in twisted CVD graphene, which was decorated with electrochemically deposited Co particles forming an ohmic contact with the graphene sheet. The temperature and magnetic field dependences of the sheet resistance R(T,B) in the pristine and decorated twisted graphene on silicon oxide substrate are compared. The coexistence of the negative (at magnetic fields with induction B below 1 T) and positive (B higher than 1 T) contributions to the magnetoresistive effect in both types of samples is shown. The R(T,B) dependences are analyzed in fraimwork of the theory of two-dimensional interference quantum corrections to Drude conductivity, taking into account the competition of the contribution from the hopping conduction mechanism. It has been shown that in the studied temperatures range (2-300 K) and magnetic fields (up to 8 T), when describing the transport of charge carriers in the studied samples, it is necessary to take into account at least three interference contributions to the conductivity: from weak localization, intervalley scattering, and breaking of pseudospin chirality, as well as warping of graphene due to thermal fluctuations.

Phase-change memory is based on a change in the optical, electrical, or other properties of a substance during a phase transition, for example, transition from the amorphous to the crystalline state. Already realized and potential applications of such memory are associated with the use for this purpose of multicomponent alloys based on metals, semiconductors. However, single-component nanoparticles, including Si ones, are also of interest in view of the prospects for their use as nanoscale memory units. In particular, possibility of creating such memory units is confirmed by the fact that the bulk phase of the amorphous silicon has an optical absorption coefficient which is by an order of magnitude greater than that of the crystalline, although, it is difficult to release this effect for an individual nanoparticle whose size does not exceed the wavelength of light. In this work, using molecular dynamics (MD) and the Stillinger-Weber potential, we studied the laws of melting and conditions of crystallization for silicon nanoparticles containing up to 100,000 atoms. It has been shown that upon cooling a silicon nanodroplet at a rate of 0.2 TK/s and higher rates, its transition into the amorphous state takes place, whereas single-component metal nanodroplets crystallize even at cooling rates of 1 TK/s. Upon subsequent heating of amorphous silicon nanoparticles containing more than 50,000 atoms, they crystallize in the definite temperature range 1300—1400 K. It is concluded that it is principally possible to create memory units based on the above phase transitions. The transition of a nanoparticle to the amorphous state is achieved by its melting and subsequent cooling to the room temperature at a rate of 0.2 TK/s, and switching to the crystalline state is achieved by heating it to 1300—1400 K at a rate of 0.2 TK/s and subsequent cooling. On the basis of results of MD experiments, a conclusion is made that there exist a minimal size of silicon nanoparticles, for which producing memory units based on the change of the phase state, is not possible. It was found that for the temperature change rate of 0.2 TK/s, the minimal size in question 12.4 nm that corresponds to 50,000 atoms.

The NiCo/C metal-carbon nanocomposites based on the NiCl2/CoCl2/Polyacrylonitrile (PAN) precursors were synthesized using IR heating. The results of studies of NiCo/C nanocomposites by X-ray phase analysis, transmission electron microscopy, and vibration magnetometry showed the dependence of the structure and properties of NiCo/C nanocomposites on the synthesis temperature, concentration, and metal ratio in the precursor. According to the results of the X-ray phase analysis, it was found that during the IR pyrolysis of the precursor, NiCo metal nanoparticles are stabilized in the carbon matrix, an increase in the synthesis temperature from 350 to 800 °C leads to an increase in the average size of nio nanoparticles from 10 to 80 nm, it is established that the formation of the alloy occurs due to the gradual dissolution of cobalt in nickel with the simultaneous transition of cobalt from the hcp modification to FCC. The structure of nanocomposites was shown by transmission electron microscopy of samples synthesized at 600 °C. It was found that with an increase in the metal concentration in the precursor from 10 to 40 wt.%, the average size of NiCo nanoparticles increases and the concentration of nanoparticles in the carbon matrix increases. The study of the magnetic properties of nanocomposites showed that with an increase in the content of metals in the precursor from 10 to 40 wt.%, an almost linear increase in the saturation magnetization from 5.94 to 25.7 A · m2/kg is observed. A change in the ratio of metals from Ni : Co = 4 : 1 to Ni : Co = 1 : 4 causes an increase in magnetization from 11.46 to 23.3 A · m2/kg.

Buckypapers (BP) with carbon nanotubes (CNT) are very promising for a lot of applications, in which their high conductance, strength and small weight are required. In this work, isotropic BP were prepared using the solution-based deposition that includes the single walled carbon nanotubes (SWCNT) dispersion and the dispersion filtration from a solvent. To increase the BP conductivity, the orientation of the SWCNT bundles composing BP and a following iodine doping were applied. The method of extrusion through the narrow (300 µm) gap was used for the SWCNT orientation. The temperature dependences of conductance for isotropic, oriented and doped BP were studied to understand the effect of CNT alignment and the mechanism of transport through SWCNT BP. It was shown that bundle orientation increases the BP conductivity from ~10³ S × cm^-1 to ~10⁴ S × cm^-1, and iodine doping of oriented samples additionally increase the conductivity by an order. The fluctuation – assisted tunneling between CNT bundles was used to describe the mechanism of low temperature conductivity.

The effect of electron irradiation with energy of 2.5 keV on the MOS structure Al/SiO2/Si capacitance-voltage (C-V) characteristics have been studied. At chosen beam energy the electron penetration depth is lower than the dielectric thickness that allows to reveal the contribution of excess carrier transport to the trap formation on the SiO2/Si interface. It was established that the electron beam irradiation leads to a significant change in the C-V characteristics slope, i.e. to to the trap formation at the interface. A study of effect of bias applied to the investigated structure before and during the electron beam irradiation was carried out. It was established that while the bias applied before irradiation practically did not affect the C-V characteristics of the investigated MOS structure, the positive voltage applied to metallization during irradiation produced a pronounced effect on the C-V curve changes. At the same time the C-V characteristics after irradiation with zero and negative voltage were very similar. The investigation of stability of changes produced by the electron beam irradiation showed that the C-V curves are slowly restored even at room temperature. An applied negative bias was found to slow down the charge relaxation process.

The use of «warm liquid» tetramethylsilane (TMS) is relevant in large massive calorimeters (with a volume of several hundred liters) to search for processes with very low energy releases. This direction is called «non-accelerator» experiments with low-background detectors.

The economic feasibility of using aluminum as a conductive material is explained by the favorable ratio of its cost to the cost of copper. In addition, one should take into account the factor that the cost of aluminum remains practically unchanged for many years. When using conductive aluminum alloys for the manufacture of thin wire, winding wire, etc. Certain difficulties may arise in connection with their insufficient strength and a small number of kinks before fracture. In recent years, aluminum alloys have been developed, which even in a soft state have strength characteristics that allow them to be used as a conductive material. One of the promising areas for the use of aluminum is the electrical industry. Conductive aluminum alloys type E-AlMgSi (aldrey) are representatives of this group of alloys and treats heat-strengthened alloys. They are distinguished by high strength and good ductility. These alloys with appropriate heat treatment acquires high electrical conductivity. The wires made from it are used almost exclusively for overhead power lines.
In the work presents the results of the study of the anodic behavior of aluminum alloy E-AlMgSi (aldrey) with tin, in a medium electrolyte 0.03; 0.3 and 3.0% NaCl. A corrosion-electrochemical study of alloys was carried out using the potentiostatic method on a PI-50-1.1 potentiostat at a potential sweep rate of 2 mV/s. It is shown that alloying E-AlMgSi (aldrey) c with tin increases its corrosion resistance by 20%. The main electrochemical potentials of the alloys when doping with tin are shifted to the positive range of values, and from the concentration of sodium chloride in the negative direction of the ordinate axis.

Strontium ferromolybdate (Sr₂FeMoO_6-δ, SFMO) having a double Perovskite structure shows good promise as a basic material for spintronics. However SFMO has not yet found wide application due to the low reproducibility of its magnetic properties which partially originates from their strong dependence on the ordering degree of Fe and Mo ions in the B´ and B² sublattices of double perovskite A₂B´B²O₆. We have considered a rapid method of determining strontium ferromolybdate disorder degree. Sublattice population with Fe and Mo ions has been estimated for stoichiometric and nonstoichiometric Sr₂FeMoO_6-δ with a 5% Fe and Mo excess, respectively. We have calculated the intensity ratio between the superstructural ordering (101) peak and the most intense (112 + 200) peak. The calculated curves have been fitted to the analytical expression for similar cases known from literature. The calculation results obtained using this method are in agreement with the results of experimental data processing using the Rietveld method accurate to within ±25 %. Thus this method can be used instead of the Rietveld method if the exposure time set in an X-ray diffraction experiment is insufficient. We have discussed the dependence of the I(101)/I(112 + 200) peak intensity ratio on various factors including diffraction peak instrumental broadening, peak twinning due to grain size reduction, thin film lattice parameter variation due to substrate lattice mismatch and lattice parameter variation due to oxygen vacancies. The method is useful as it allows evaluating the superlattice ordering degree in Sr₂FeMoO_6-d without large time consumption for X-ray diffraction pattern recording and processing with the Rietveld method which may be essential when dealing with large amounts of experimental data