http://repository.enu.kz/handle/enu/10679 2026-04-04T03:30:35Z http://repository.enu.kz/handle/enu/10717 Phase composition and thermoelectric properties of the nanocomposite alloys NaxCu2−x−yS Kubenova, M.M.; Balapanov, M.Kh.; Kuterbekov, K.A.; Ishembetov, R.Kh.; Kabyshev, A.M.; Yulaeva, Y.Kh. Nanocrystalline alloys of the compositions Na 0.05 Cu 1.95 S, Na 0.075 Cu 1.925 S, Na 0.10 Cu 1.90 S, Na 0.125 Cu 1.750 S, Na 0.15 Cu 1.85 S, Na 0.17 Cu 1.80 S, Na 0.20 Cu 1.77 S were synthesized in a melt medium mixtures of hydroxides NaOH and KOH at a temperature of about 165 ◦ C. X-ray phase analysis showed that the alloys are heterophasic and consist of phases of Cu 9 S 5 digenite, CuS 2 copper disulfide, Covellite CuS, Cu 7 S 4 anilite in various combinations. The crystallite sizes range from 16 to 160 nm. The degree of crystallinity of the alloys slightly increases with an increase in the sodium content from 68% in Na 0.05 Cu 1.95 S to 81% in Na 0.20 Cu 1.77 S. A quasi-one-dimensional Na 2 Cu 4 S 3 phase was detected in the composition of the Na 0.20 Cu 1.77 S alloy. The measured values of the conductivity of the alloys are two orders of magnitude lower than in isolated pure Cu 9 S 5 , CuS 2 , CuS, Cu 7 S 4 , of which the alloys consist. An activation temperature dependence of the conductivity is observed in the region from 300 K to 360 K with an activation energy of 0.08 - 0.15 eV. The reason for the low conductivity of the alloys is assumed to be the presence of weakly conducting interfacial layers and sodium doping of non-stoichiometric phases Cu 9 S 5 (Cu 1.8 S) and Cu 7 S 4 (Cu 1.75 S), leading to the compensation of holes by electrons of impurity sodium atoms. The measured values of the coefficient of thermo-emf alloys at room temperature lie in the range from 0.032 to 0.147 mV/K. Due to the low thermal conductivity of the order of 0.2 W/mK, a rather high dimensionless thermoelectric figure of merit ZT ≈ 0.28 at 570 K was obtained for the composition Na 0.15 Cu 1.85 S. 2020-01-01T00:00:00Z http://repository.enu.kz/handle/enu/10716 Comparison of aluminum and manganum concentration in Akmola region, Kazakhstan Zhumalina, A.G.; Sambayev, E.K.; Sakaguchi, A.; Endo, S.; Tanaka, K.; Kajimoto, T.; Kawano, N.; Suleimenov, T.B.; Zhumadilov, K.Sh.; Hoshi, M. The results of seasonal Al and Mn activity on the surface of the atmosphere above the city of Nur-Sultan are shown from October 2016 to January 2017. The technique of sampling aerosols in various fractions and further analysis of the data are described. Together with scientists from the University of Hiroshima (Hiroshima, Japan) and the University of Tsukuba (Tsukuba, Japan), the composition of aerosols in the air of Astana was monitored. The aim of the project was to develop a methodology for sampling aerosols in various fractions and conduct measurements on an ongoing basis. The studies were carried out using a high-volume air sampler and a cascade of impactors that measure the size distribution and the respirable mass fraction of airborne particles of the environment. Fiberglass filters, which are a commonly used material for sample collection, were also used. The data obtained in the study of aerosol samples using a cascade of impactors allowing the selection of aerosols with sizes up to 0.49 µm showed the content of aluminum isotope in the atmosphere of the city. The smaller the clearance gap, the more particles are trapped. On average, aerosols were taken from more than 200 thousand cubic meters of air. 2020-01-01T00:00:00Z http://repository.enu.kz/handle/enu/10715 Neutron transfer and nuclear breakup in 208Pb (11Li, 9 Li) reaction Azhibekov, A.K.; Samarin, V.V.; Kuterbekov, K.A. Neutron transfer and nuclear breakup processes in reaction with weakly bound nucleus 11Li at energies near the Coulomb barrier are investigated in the framework of the time-dependent Schrödinger equation. The evolution of probability density of outer weakly bound neutrons of 11Li in the collision with 208Pb was studied. The probabilities and cross sections of outer neutrons removal (breakup processes and transfer to target nucleus) were calculated. Theoretical predictions of the two-neutron removal probability values were obtained for angles from 140◦ to 180◦. The theoretical results have close similarity with experimental data for the two-neutron removal in reaction 208Pb (11Li,9 Li). 2020-01-01T00:00:00Z http://repository.enu.kz/handle/enu/10714 The study of the applicability of invar nanostructures for the reduction of p-nitrophenyl compounds Borgekov, D.B.; Zdorovets, M.V.; Shlimas, D.I.; Kozlovskiy, A.L.; Khlebnikov, N.A.; Kaniukov, E.Yu. The results of the study of the phase composition of iron-nickel nanostructures susceptible to electron irradiation on the catalytic reduction of p-nitrophenyl compounds are presented. In the course of the studies, it was found that the nanostructures irradiated with a dose of 250 kGy, which are characterized by the presence of two phases, with the domination of the FeNi phase, have the highest recovery rate. In this case, nanostructures irradiated with a dose of 250 kGy, which showed the highest catalytic reaction rate, have a fairly short lifetime, which may be due to the rapid degradation of the surface of the nanotubes as a result of the interaction of the catalyst with the medium. 2020-01-01T00:00:00Z