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Eurasian Journal of Physics and Functional Materials

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Vol 5, No 3 (2021)
169-173 224
Abstract

In this work the nonrelativistic ionization energies3He2+µ-e-and4He2+µ-e-of helium-muonicatoms are calculated for S states.The estimates are based on the variational principle of exponentialexpansion. Convergence of the numerical values of variational energies is studied by increasing anumber of the basis functions N. That allows to claim that the obtained energy values have 30-33signi cant digits for S states

174-182 238
Abstract

For the first time after the mothballing of the uranium mine, comprehensive studies were carried out to assess the radiation situation in the territory of the Saumalkol settlement in the North Kazakhstan region. On the territory of the Saumalkol settlement, pedestrian and automobile gamma surveys were carried out, the rates of the ambient equivalent dose of gamma radiation, the flux density of . and . 220Rn particles and the equivalent equilibrium volumetric activity of daughter products of 222Rn and isotopes in residential premises were measured. Samples of soil, water and bottom sediments were taken for laboratory radio spectrometric and radiochemical analyzes. At all measurement points, geographic coordinates were determined using a satellite navigation device. On the territory of the abandoned mine and in some areas of the Saumalkol settlement, anomalous areas with a high value of gamma radiation power from 0.35 to 1.08 Sv/h were revealed. In the residential premises of the Saumalkol village, the equivalent equilibrium volumetric activityof daughterproductsof radon isotopesisupto8 times higher than the norm (200 Bq/m3).

183-191 148
Abstract

The intrinsic mechanisms of the unusual metallic transports of three types of relevant charge carriers (large polarons, excited (dissociated) polaronic components of bosonic Cooper pairs and bosonic Cooper pairs themselves) along the CuO2 layers of high-Tc cuprates are identified and the new features of metallic conductivity in the CuO2 layers (i.e. ab -planes) of underdoped and optimally doped cuprates are explained. The in-plane conductivity of high-Tc cuprates is associated with the metallic transports of such charge carriers at their scatteringbylattice vibrations in thin CuO2 layers. The proposed charge transport theory in high-Tc cuprates allows to explain consistently the distinctive features of metallic conductivity and the puzzling experimental data on the temperature dependences of their in-plane resistivity rab . In underdoped and optimally doped cuprates the linear temperature dependence of rab (T) above the pseudogap formation temperature T . is associated with the scattering of polaronic carriers at acoustic and optical phonons, while the different (upward and downward) deviations from the linearity in rab (T) below T . are causedbythe pseudogap effect on the conductivity of the excited Fermi components of bosonic Cooper pairs andbythe dominating conductivity of bosonic Cooper pairs themselves in the normal state of these high-Tc materials.

192-199 157
Abstract

The paper presents data on changes in strength properties, including data on microhardness, crack resistance, bending strength and wear of BeO ceramics as a result of irradiation with heavy accelerated ions. O2+ Kr15+ The following types of ions were selected as heavy ions: (28 MeV), Ar8+ (70 MeV), (147 MeV), Xe22+ (230 MeV). Radiation doses were 10 13 -10 15 ion/cm2 , which make it possible to assess the effect of both single defects arising from radiation, and cluster overlapping defective areas occurring at large radiation doses. During the studies carried out, it was found that an increase in the ion energy and, consequently, in the damaging ability and depth of the damaged area, leads to a sharp decrease in the strength mechanical characteristics of ceramics, which is due to an increase in defective areas in the material of the near-surface damaged layer. However, an increase in irradiation dose for all types of exposure results in an almost equilibrium decrease in strength characteristics and the same trend of change in strength characteristics. The obtained dependencies indicate that the proposed mechanisms responsible for changing the strength properties can, under certain assumptions, be extrapolated to various types of exposure to heavy ions in the energy range (25-250 MeV).

200-208 150
Abstract

The mechanisms of creation of impurity and intrinsic electron-hole trapping centers in Na2SO4 . Cu crystals have been investigated by spectroscopic methods. It is shown that impurity and intrinsic electron-hole trapping centers in the crystal lattice Na2SO4 . Cu are created in the same energy distances approximately 3.87-4.0 eV and 4.43-4.5 eV. During the annealing of electron-hole trapping centers, the energy of the re combination processes is transferred to impurities.

209-221 164
Abstract

This work presented a study of the structure, hardness and wear resistance of 65G steel treated with electrolyte-plasma hardening under different conditions. The electrolyte-plasma hardening technology and a laboratoryinstallation for the realisation of electrolyte-plasma hardening are also described. After electrolyte-plasmahardening,wehave established thata modifiedlayer consistsofthe a-phase (martensite) and M3C cementite. The study results showed that electrolyte-plasma hardening makes it possible to obtainlayersonthe65G steel surface thatprovidesan increasein microhardnessby2.6 times,wear resistanceby two times,resistance to abrasivewearby1.7 times compared to the original samples. In addition, local hardening ensures the achievement of technical and economic effects due to the absence of the need to isolate an unwanted site of parts, processing only the areas requiring hardening.

222-234 357
Abstract

In this research, the structure parameters, conducting and dielectric properties of Na3Fe2(PO4)3 and Na2FePO4F polycrystals were studied obtained by solid-phase synthesis. The phase transition temperatures, conducting and dielectric parameters of Na3Fe2(PO4)3 and Na2FePO4F polycrystals were refined. A comparative evaluation of the conductive properties of Na3Fe2(PO4)3 and Na2FePO4F polycrystals is given in this article. The prospects of using of Na3Fe2(PO4)3 and Na2FePO4F are justified as electrode materials in sodium ion batteries.

235-241 155
Abstract

The mechanism of creation of electron-hole trapping centers in CaSO4 at 15-300 K was investigated by the methods of vacuum-ultraviolet and thermoactivation spectroscopy. It is shown that electron-hole trapping centers are formed upon trap of electrons in the anionic complexes SO2. and localization 4 of holes in the form of SO. radical. Based on the measurement of the spectrum of excitation of 4 long-wavelength recombination emission at 3.0-3.1 eV and 2.7 eV, the energy distance of the formed electron-hole trapping centers was estimated (4.43 eV and 3.87 eV).

242-250 129
Abstract

In this paper, the features of the characteristics of model thin-film solar cells based on the non-toxic multicomponent compound CuZn2AlS4(CZAS) are considered. The main parameters (open-circuit voltage, short-circuit current, fill factor, efficiency) and characteristics (quantum efficiency, current-voltage characteristic) of thin-film solar cells based on CZAS have been determined. The minimum optimal thickness of the CZAS absorber is found (1-1.25 microns). Deterioration of the performance of solar cells with an increase in operating temperature (280-400 K) is shown. It is revealed that in the wavelength range of 390-500 nm CZAS has a high external quantum efficiency, which allows its use in designs of multi-junction solar cells designed to absorb solar radiation in the specified range. It is shown that the combination of CZAS films with a buffer layer of non-toxic ZnS increases the performance of solar cells.



ISSN 2522-9869 (Print)
ISSN 2616-8537 (Online)