Vol 2, No 3 (2018)
191-205 403

To obtain the interactions which cause neutrino flavor conversion, we introduce a horizontal symmetry into the standard model (SM) and propose the hypothesis that new interactions generated by the horizontal symmetry lead to neutrino flavor conversion and oscillation. To support our hypothesis, we evaluate the flavor conversion probability by new interactions by utilizing the definition of cross section, and the prediction is consistent to experimental data. From our hypothesis, neutrino oscillation is fluctuation of flavor distribution before arriving at equilibrium.

206-218 493

The aim of the article is to review the latest achievements in the field of magnetron deposition of thinfilm yttria-stabilised zirconia (YSZ) electrolyte for solid oxide fuel cells (SOFC). The main attention is paid to the use of magnetron sputtering for formation of YSZ electrolyte up to 10 μm thick on the anode substrates of intermediate-temperature SOFCs operating at a temperature of (600 - 800)°C . The influence of the types of power sources and such deposition parameters as substrate temperature, substrate bias voltage, post-annealing treatment, etc., as well as the morphology of the anode substrate surface on the microstructure and properties of the deposited electrolyte is analyzed. It is shown that the magnetron sputtering method, despite its relatively high cost and complexity, is applicable to large area SOFC cells and is competitive compared to traditional methods of electrolyte formation, such as tape casting, tape calendering, electrophoretic deposition and screen printing.

219-230 430

We demonstrate that the unconventional electron-phonon interactions, charge inhomogeneity and charge ordering in underdoped cuprates play an important role in metal-insulator transitions and nanoscale phase separation. In so doing, we argue that charge carriers (i.e. hole polarons) in these systems segregate into insulating (carrier-poor) and metallic/superconducting (carrier-rich) regions as a result of their specific ordering. We show that the metal-insulator transitions, nanoscale phase separation and coexisting insulating and metallic/superconducting phases are manifested in the unusual temperature dependences of the magnetic susceptibility and resistivity and in the suppression of superconductivity in various underdoped cuprates.

231-241 463

Synthesis, X-ray phase analysis, electron microscopy and investigations of the thermoelectric and thermal properties of nanocrystalline copper sulfide alloys contained sodium are presented. At room temperature, the alloys are a mixture of three phases of copper sulfide - the monoclinic phase of Na2Cu4S3 , the hexagonal phase of Cu2S and the cubic phase of Cu9S5 (digenite). The predominant phase is Na2Cu4S3 (with content from 57 to 85 volume %). The particle sizes in the compacted samples lie in the range from 20 to 400 nm. For all samples DSC studies revealed a first-order phase transition in the (370-380) K region with enthalpies from 5234 to 11720 J/kgK. The heat capacity varies within the range (0.15-0.48) J/(gK). The electrical conductivity, Seebeck coefficient and thermal conductivity were measured in the temperature range from 290 to 590 K. A very low thermal conductivity of the samples was observed in the interval of (0.1-0.6) Wm -1 K -1 . The Seebeck coefficient has a value higher than 0.2 mV/K for Na0.15Cu1.85S composition, but a low electrical conductivity about 10 S/cm limits the maximum dimensionless thermoelectric efficiency ZT of the material at 0.3 in the temperature range 290-590 K.

242-250 408

The article researches formation of ceramic coatings of zirconium dioxide (ZrO2) on the X12CrNi1810Ti steel surface after mechanical alloying. Study of coatings’ surface showed coalescence of defected coating’s particles with created subgrains and this process is more representative due to different toughness of zirconium oxide and steel. It is suggested that adhesive bond between the coating and support structure is provided by strain welding of the powder on the support structure coating. When using X-phase analysis neither diffusive mixing of coating/support structure components or formation of new compounds and phase changes was revealed. Surface contamination of the coating with carbon was found out and it was getting less towards the border between the coating and support structure. It could be due to mechanical sorption of carbon dioxide from the environment.

251-258 479

The paper presents the results of investigations of the structure and phase composition of titanium boride coatings deposited by magnetron sputtering from a target of a complex composition onto a steel substrate. The target for magnetron sputtering was obtained by sintering boron carbide and titanium powders. The structure and elemental composition of the coating were studied using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and the energy-dispersive spectral (EDS). It was established that the coatin g structure is a mixture of Ti2B5 and TiB12 phases with the total boron content of ≈ 80 at %, which is 4 times higher than the boron concentration in the coatings obtained by plasma spraying of the B4C powder. The use of magnetron sputtered coatings of titanium boride coatings as neutron-absorbing materials will allow to reduce the coating thickness in comparison with the coatings from boron carbide synthesized by plasma spraying methods.

259-266 443

The article examines the changes of the structural-phase states and the microhardness of the R6M5 steel surface layer after electrolytic-plasma nitriding. It is found that after electrolytic-plasma nitriding of the R6M5 steel surface, diffusion layer is formed, which is a nitrogen martensite. The phase composition of the diffusion layer varies depending on the nitriding temperature. An increase of R6M5 steel microhardness, depending on structural-phase state, is found out. The main factor, in fluencing the increase of microhardness of R6M5 high-speed steel with electrolytic-plasma nitriding, is the formation of nitro . gen martensite with monophasic nitride Fe4N ( γ-phase), as well as the formation of fine inclusions, hardening phases in the surface layers.

267-273 430

The X-ray luminescence spectra at low temperature (90K) uniaxial deformation were researched for KI and KI-Na crystals, that were stored for more than 10 years. The following regularities were observed: firstly, the intensities of the intrinsic emission bands at 3.3 eV (π) and 4.1 eV ( σ ) become equal in com- parison with freshly grown crystals; and secondly, with an increase in the degree of low-temperature uniaxial deformation, a gradual shift of the emission spectra occurs in two directions: the luminescence maximum at 3.3 eV shifts towards short wavelengths, the final position is fixed at 3.9 eV, which prac- tically merges with σ-luminescence; the radiation maximum at 3.0 eV (Ex-radiation) is shifted toward long wavelengths, the final position which is fixed at 2.8 eV. Thus, low temperature uniaxial deformation leads to the separation of the emission spectra at 3,3 eV(π) → 3,9 eV and 3.0 eV ( Ex ) → 2,8 eV, which are interpreted by the separation of weak → on and weak → strong exciton configurations , respectively.

274-292 4311

Cathode materials with mixed ion-electron conductivity (MIEC) are necessary for the development of low or intermediate temperature solid oxide fuel cells. Perovskite and perovskite-related materials are promising candidates on this role. In the review the conductivity and the thermal expansion of materials with various types of perovskite-related structures such as pure perovskite, double perovskite, brownmillerite and Ruddlesden-Popper phases have been compared. And the literature data on the values of the electronic and ionic conductivities, the oxygen diffusion coefficient, and the thermal expansion coefficient of various compositions have been collected. It was shown that the disordered cubic perovskites possess the higher electronic conductivity whereas the layered perovskites and materials with the Ruddlesden-Popper structure have higher ionic conductivity and lower value of thermal expansion.

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