The materials of The International Scientific – Practical Conference is presented below.
The Conference reflects the modern state of innovation in education, science, industry and social-economic sphere, from the standpoint of introducing new information technologies.
It is interesting for a wide range of researchers, teachers, graduate students and professionals in the field of innovation and information technologies.
We report a study of epitaxial superconductive NbN films on vicinal to the X-cut of single crystal LiNbO3 substrates grown using reactive magnetron sputtering of Nb target in Ar -N2 atmosphere. It is found that the NbN films reveal sharp superconductive transition at TC= 15.2 K and anisotropy of critical current. Critical current measured along the Z direction exceeds JC along the Y direction regardless of the orientation of step edges of the vicinal surfaces. The anisotropy effect is attributed to NbN film uniaxial stress due to the lattice mismatch of NbN (0 0 1) layer along the Z direction of LiNbO3.
Charge-discharge processes of supercapacitor with carbon black KJEC 600/Li in non-aqueous electrolyte: 1 M LiPF6 in a mixture of ethylene carbonate (1/3), diethyl carbonate (1/3), dimethyl carbonate (1/3) are investigated. Galvanostatic cycling was carried out in the range from 1 to 4 V with currents from 100 to 5000 mA/g of carbon black. The maximum discharge capacity of 196 F/g has been reached. The porous structure and hydrophilic-hydrophobic properties of carbon black KJEC 600 were investigated by the standard contact porosimetry method (MSCP). The following values were obtained: total specific surface area of 2500 m2/g, total porosity of 7.8 cm3/g, hydrophilic porosity of 4.9 cm3/g, hydrophobic porosity of 2.9 cm3/g. The obtained experimental dependence of the energy efficiency has a maximum (80%) at a current of 250 mA/g. Mathematical modeling of charge-discharge processes of the supercapacitor is developed with taking into account the charging of the double electric layer (EDL) and adsorption of lithium ions according to the Butler-Volmer equation and the Frumkin isotherm for the carbon electrode are taken into account. From the comparison of the calculated and measured charge-discharge curves it follows that these curves are satisfactorily consistent with each other, which indicates the correctness of the model. The density of the exchange current and the specific capacitance of the EDL refereed to the true surface found by the fitting are equal to i0,ad = 2.8 × 10−29A/сm2 and Cdl = 3.5 μF/сm2 respectively.
On the basis of the developed model for different specific currents the energy efficiency dependences on the exchange current density of the adsorption reaction were calculated. Interestingly, these dependencies have a minimum. Based on the model, the profiles of the potential the surface coverage of lithium ions were also calculated.
The structural and spectroscopic features of the EuAl3(BO3)4 individual skeletal microcrystals synthesized by a melt solution method have been studied. Their infrared spectra taken from the as-grown microcrystal surfaces mainly contain the lines of the rhombohedral modification of EuAl3(BO3)4 and additional peaks of its monoclinic modification. TEM and X-ray diffraction studies confirm that these additional peaks in the IR spectra belong to the monoclinic C2/c polytype of the EuAl3(BO3)4 compound. We are the first to demonstrate the presence of coherent monoclinic domains in rhombohedral EuAl3(BO3)4 crystals by TEM. Cathodoluminance spectroscopy shows that the microcrystals generate strong emission lines in the range 580–630 nm, and their intensities are strongly influenced by the crystal orientation.
A method for the construction of microwave devices with longitudinal interaction is proposed. Devices of the present type create uniform cross-sectional distribution of temperature of rods made of polymer composite materials. Results from theoretical and experimental investigations of the cross-sectional distribution of the temperature of the material of the rod as well as the parameters of the microwave device are presented.
In this study, we grew Cu co-doped single crystals of a topological superconductor candidate SrxBi2Se3, and studied their structural and transport properties. We reveal that the addition of even as small an amount of Cu co-dopant as 0.6 atomic %, completely suppresses superconductivity in SrxBi2Se3. Critical temperature (∼2.7 K) is rather robust with respect to co-doping. We show that Cu systematically increases the electron density and lattice parameters a and c. Our results demonstrate that superconductivity in SrxBi2Se3-based materials is induced by significantly lower Sr doping level x<0.02 than commonly accepted x∼0.06, and it strongly depends on the specific arrangement of Sr atoms in the host matrix. The critical temperature in superconductive Sr-doped Bi2Se3 is shown to be insensitive to carrier density.
We report a comprehensive study of physical properties of the binary superconductor compound SnAs. The electronic band structure of SnAs was investigated using both angle-resolved photoemission spectroscopy (ARPES) in a wide binding energy range and density functional theory (DFT) within generalized gradient approximation (GGA). The DFT/GGA calculations were done including spin-orbit coupling for both bulk and (111) slab crystal structures. Comparison of the DFT/GGA band dispersions with ARPES data shows that (111) slab much better describes ARPES data than just bulk bands. Superconducting properties of SnAs were studied experimentally by specific heat, magnetic susceptibility, magnetotransport measurements and Andreev reflection spectroscopy. Temperature dependences of the superconducting gap and of the specific heat were found to be well consistent with those expected for the single band BCS superconductors with an isotropic s-wave order parameter. Despite spin-orbit coupling is present in SnAs, our data shows no signatures of a potential unconventional superconductivity, and the characteristic BCS ratio 2/Tc = 3.48 − 3.73 is very close to the BCS value in the weak coupling limit.
Here we report targeted high-pressure synthesis of two novel high-TC hydride superconductors, P63/mmc-ThH9 and Fm3m-ThH10, with the experimental critical temperatures (TC) of 146 K and 159–161 K and upper critical magnetic fields 38 and 45 Tesla at pressures 170–175 Gigapascals, respectively. Superconductivity was evidenced by the observation of zero resistance and a decrease of TC under external magnetic field up to 16 Tesla. This is one of the highest critical temperatures that has been achieved experimentally in any compound, along with such materials as LaH10, H3S and HgBa2CaxCu2O6+z. Our experiments show that fcc-ThH10 has stabilization pressure of 85 GPa, making this material unique among all known high-TC metal polyhydrides. Two recently predicted Th-H compounds, I4/mmm-ThH4 (>86 GPa) and Cmc21-ThH6 (86–104 GPa), were also synthesized. Equations of state of obtained thorium polyhydrides were measured and found to be in excellent agreement with the theoretical calculations. New phases were examined theoretically and their electronic, phonon, and superconducting properties were calculated.
The FeSe wires and tapes with Fe (S22 steel) and Cu/Nb sheath were fabricated by various modifications of the powder-in-tube (PIT) method. The superconducting critical parameters (upper critical field, critical current, critical temperature) depending on heat treatment time were investigated using resistive R(T) and transport measurements I (V) in magnetic fields up to 9T. The low-temperature annealing up to 72 h improve superconducting properties of superconducting wire with steel sheath. However, the annealing is the cause of superconducting wires degradation due to deterioration of contacts between the steel shell and the FeSe core. We show that industrial PIT technology of manufacturing Nb3Sn wires and tapes might be adopted for iron-based superconductors. Moreover, industrial PIT is a promising technique for fabricating large scale and high-quality superconducting wire and tapes. In addition, we show that fine grinding of the FeSe bulks leads mainly to a phase transition from the tetragonal to the hexagonal crystal structure that exhibits no superconductivity.
The paper considers an influence of different kinds of radio-frequency plasma treatments onto modification of MIS structures with a thermal SiO2 film which is aimed at improvement of electro-physical parameters of the film. It was found that for the modification of MIS structures it is more preferable to utilize the oxygen plasma radio-frequency plasma treatment performed by a setup with the parallel-plate-type reactor. This is due to the fact that setup allows to have lesser degradation of charge characteristics of the gate dielectric in comparison with a setup with the cylindrical quartz reactor. The radio-frequency plasma treatment stimulates restructuring of SiO2 film and, as a result, diminishes possibility of sample breakdown and raises injection and radiation stability of the samples.