http://repository.enu.kz/handle/enu/20363 2026-04-04T00:27:30Z http://repository.enu.kz/handle/enu/30458 Wet Chemical Synthesis of AlxGa1−xAs Nanostructures: Investigation of Properties and Growth Mechanisms Suchikova, Yana; Kovachov, Sergii; Bohdanov, Ihor; Konuhova, Marina; Zhydachevskyy, Yaroslav; Kumarbekov, Kuat; Pankratov, Vladimir; Popov, Anatoli I. This study focuses on the wet chemical synthesis of AlxGa1−xAs nanostructures, highlighting how different deposition conditions affect the film morphology and material properties. Electrochemical etching was used to texture GaAs substrates, enhancing mechanical adhesion and chemical bonding. Various deposition regimes, including voltage switching, gradual voltage increase, and pulsed voltage, were applied to explore their impact on the film growth mechanisms. SEM analysis revealed distinct morphologies, EDX confirmed variations in aluminum content, Raman spectroscopy detected structural disorders, and XRD analysis demonstrated peak position shifts. The findings emphasize the versatility and cost-effectiveness of wet electrochemical methods for fabricating high-quality AlxGa1−xAs films with tailored properties, showing potential for optoelectronic devices, high-efficiency solar cells, and other advanced semiconductor applications. 2024-01-01T00:00:00Z http://repository.enu.kz/handle/enu/30457 USING COAL FLOTATION WASTE AS A HEAT-INSULATING BILLING FOR THE HEAD PART OF A FORGING INGOT Ibraev, I.K.; Ibraeva, O.T.; Aitkenov, N.B.; Sakipov, K.E. The experience of using coal flotation waste as a weakly exothermic insulating backfill for insulating the head part of forging dead-melted steel ingots is presented. It has been shown that when using weakly exothermic fills based on single-component fills in the form of coal flotation waste, it is possible to reduce the chemical heterogeneity of the ingot by producing a closed shrinkage cavity, which allows halving heat loss and depth of penetration of shrinkage looseness into the body of the ingot, reducing the segregation of impurities, compacting the head part of the ingot and increasing the yield; moreover, the profitable part of the ingot is more dense and less contaminated with nonmetallic inclusions. The studied patterns of the formation of a closed shrinkage cavity with a dense “bridge” in the head part of a dead-melted steel ingot made it possible to develop and implement a technology for casting large forging ingots of sufficiently high quality using weakly exothermic heat-insulating materials based on metallurgical waste (coke screenings, coal flotation waste). 2024-01-01T00:00:00Z http://repository.enu.kz/handle/enu/30456 Unveiling the Structural and Optical Properties of MgAl2O4 Single Crystals Irradiated by Swift Heavy Ions Akilbekov, Abdirash; Kiryakov, Arseny; Dauletbekova, Alma; Aralbayeva, Gulnara; Akylbekova, Aiman; Ospanova, Zhulduz A synthetic single crystal of magnesium-aluminate spinel was irradiated perpendicularly to the (111) plane with swift heavy xenon ions with an energy of 220 MeV. The modified layer was attested based on Raman scattering spectra recorded while focusing on the surface. A decrease in surface crystallinity was observed, reflected in the changes in fundamental optical characteristics such as the band gap and the energies of static and dynamic disorder. In this study, we demonstrate, along with the modification of optical characteristics and the formation of a disordered layer, the creation of new optically active centers. The luminescent properties of these centers were analyzed. The effect of temperature flare-up in the 3.4 eV band of the excitation spectrum was determined. The low sensitivity of Cr3+ luminescence to SHI is demonstrated. 2024-01-01T00:00:00Z http://repository.enu.kz/handle/enu/30455 Thin films of polyanilines and polymer nanocomposites for the development of chemical sensors Salikhov, R.B.; Ostaltsova, A.D.; Salikhov, T.R.; Balapanov, M.Kh.; Bugybayev, E.S. The control and monitoring of humidity levels and the concentration of hazardous gases in the atmosphere are subjects of significant interest across various fields. Consequently, current research focuses primarily on the advancement of sensitive materials tailored for humidity and toxic gas sensors, aiming to achieve heightened performance and sensitivity while operating efficiently at ambient temperatures. Investigative efforts delve into exploring thin film compositions comprising polyanilines and their derivatives, as well as polymer nanocomposites, with the intention of fabricating chemical sensors. Diverse configurations of chemical sensors, manifesting as thin-film electronic devices such as resistive and transistor structures, are under scrutiny. The surface morphology of these thin films is meticulously examined through scanning electron microscopy. Furthermore, the electrical characteristics, as elucidated by the current-voltage profiles, of resistive and transistor structures utilizing thin films of polyanilines and their derivatives alongside polymer nanocomposites, are analyzed in relation to variations in ambient humidity levels and concentrations of hazardous gases such as ammonia vapors. The outcomes of this investigation underscore the potential utility of organic compound-based thin films in the realm of chemical sensor development. 2024-01-01T00:00:00Z