http://repository.enu.kz/handle/enu/10796 2026-04-04T02:22:13Z http://repository.enu.kz/handle/enu/10870 Magnetic anisotropy and stability of Fe3Ga compounds Inerbaev, T.M.; Abuova, A.U.; Dauletbekova, A.K.; Abuova, F.U.; Kaptagay, G.A.; Zakieva, Zh.; Eltizarova, M.; Barakov, A. The magnetic anisotropy energy and the stability of crystal modifications of D03 and L21 of Fe3Ga compounds are studied with the density functional theory methods. The magnetic anisotropy energy of the D03 structure is more than twice the same value for the L21 structure. The features in the electronic structure lead to the difference in the magnitude of spin-orbit interaction, explaining the found effect. The L21 structure is more thermodynamically stable in the entire range of the considered pressures. Under pressure, the considered crystal modifications of Fe3Ga lose their stability due to the appearance of imaginary frequencies in their phonon spectra. 2021-01-01T00:00:00Z http://repository.enu.kz/handle/enu/10869 Application of non-destructive neutron resonance capture analysis for investigation of women’s Old Believer cross dating back to the second half of the 17th century Mazhen, S.T.; Sedyshev, P.V.; Simbirtseva, N.V.; Yergashov, A.M.; Dmitriev, A.Yu.; Ivchenkov, V.L. Neutron Resonance Capture Analysis (NRCA) is presently being developed at the Frank Laboratory of Neutron Physics (FLNP) to determine the elemental composition of samples. The NRCA is a nondestructive method that allows measuring objects’ bulk composition. The procedure is based on detecting neutron resonances in radiative capture and the measurement of the yield of reaction products in these resonances. The experiments are carried out at the Intense REsonance Neutron source (IREN). In this study, we applied the NRCA to investigate an archaeological object provided by the Museum and Exhibition Complex (MVK) "Volokolamsk Kremlin". The object was a women’s Old Believer cross (second half of the 17th century) found in the Moscow region, Volokolamsk district, the village of Chubarovo. 2021-01-01T00:00:00Z http://repository.enu.kz/handle/enu/10868 A comparative study of promising filter materials for neutron imaging facilities Nazarov, K.M.; Kichanov, S.E.; Lukin, E.V.; Zel, I.Yu.; Kozlenko, D.P.; Zholdybayev, T.K.; Muhametuly, B.; Kenessarin, M.; Rutkauskas, A.V.; Yskakov, A.; Belova, M.O. The effect of sapphire and bismuth single-crystal filters and their combinations on the quality of neutron radiographic images and neutron tomography data has been studied. The parameters of the contrast of the neutron image were analyzed depending on the monocrystalline filters. Neutron transmission spectra were obtained for sapphire and bismuth single crystals. Additionally, the effect of filters on the overall intensity of the thermal neutron beam and the background of gamma-rays was investigated. Based on the obtained data, we assume that a single-crystal sapphire filter can be most effectively used for radiographic and tomographic installations using thermal neutrons. 2021-01-01T00:00:00Z http://repository.enu.kz/handle/enu/10867 Mechanisms for the creation of intrinsic electron-hole trapping centers in a CaSO4 crystall Nurakhmetov, T.N.; Zhangylyssov, K.B.; Zhunusbekov, A.M.; Daurenbekov, D.H.; Alibay, T.T.; Sadykova, B.M.; Yussupbekova, B.N.; Tolekov, D.A. 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− 4 and localization of holes in the form of SO−4 radical. Based on the measurement of the spectrum of excitation of 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). 2021-01-01T00:00:00Z