NNC RK Bulletin

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1729-7516

1729-7885

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Nuclear reactor physi...

Nuclear and radioacti...

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Публикации в журнале

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A THEORETICAL STUDY FROM FIRST PRINCIPLES OF THE MODIFICATION OF BARIUM TITANATE BY CARBON
(2025-07-14)
B. M. Satanova
;
Fatima U. Abuova
;
Eugene A. Kotomin
;
Aisulu U. Abuova
;
S. A. Nurkenov
Structures based on atomic thin carbon and created by combining two or more graphene-like materials with alternating oxide perovskites change the properties of the source materials and a material with new hybrid properties is formed, which in turn will be a prerequisite for the design of Functional Materials and nanostructures. Strong covalent bonds provide the surface stability of 2D crystals, and the connection between the different layers is mediated by Van der Waalst interaction. Heterostructures based on carbon materials and nanostructured ferroelectric perovskites, including barium titanate, ferromagnetic (La2/3Sr1/3MnO3, SrRuO3), alternating metal oxides are promising for the development of new multifunctional materials for memory cells, quantum computer elements, Li-ion battery anodes, photocatalysts, supercapacitors, transistors, sensor materials, solar cells, fuel cells, electrochromic devices. The paper examines the influence of the density functional theory method on the structural and energy properties of the carbon mixture on the surface of BaTiO3, which is theoretically important for catalytic purposes, in combination with the pseudopotential method of plane-waves in basis. Based on the theory of density functionality, the process of adsorption of barium titanate as a result of modification with carbon atoms with a gradual increase in concentration on a TiO2 – terminating (001) surface, pure and doped with carbon atoms, was studied. The most effective locations on the TiO2 – terminating (001) surface were the “top Ti” locations, and the state density was determined when the concentration of carbon was increased in the order of the graphene structure from 0.125 to 0.75 in the distribution of each TiO2, and the width of the Forbidden Zone was reduced by 0.27−2 eV compared to the pure surface for the considered structures. The adsorption energy was −0.5 eV for atomic oxygen adsorbed near the energy efficient location defined for carbon on a clean surface, and −2.12 eV for Molecular. For atomic oxygen adsorbed on a carbon −doped surface, the adsorption energy was reduced by −0.2 eV, and for Molecular − by −0.4 eV.
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AB-INITIO CALCULATIONS OF THE RHODIUM-DOPED (001) SURFACE OF THE RHOMBOHEDRAL PHASE BaTiO3
(2024-06-30)
Zh. Ye. Zakiyeva
;
Talgat M. Inerbaev
;
Aisulu U. Abuova
;
Fatima U. Abuova
;
N. A. Merali
The advancement of effective, durable, and economically viable photocatalytic systems aimed at solar-driven water splitting into hydrogen and oxygen represents a strategically vital pathway for future fuel and chemical production from renewable sources. Water splitting is a promising strategy for the sustainable production of renewable hydrogen and for addressing the global energy and environmental crisis. However, the large-scale application of this method is limited by the low efficiency and high cost of solar water splitting systems. The search for economical, efficient, and stable photocatalysts is crucial in the development of solar water splitting technologies. Perovskite-based photocatalysts have recently attracted considerable attention for use in solar water splitting processes due to their simple structure and flexible composition. BaTiO3 is a promising photocatalyst because of its adjustable electronic structure. Initially considered a poor photocatalyst due to its wide band gap, this material has become the focus of various strategies aimed at reducing the band gap. In this paper, we study the effect of Rh doping on the electronic structure of the (001) BaTiO3 perovskite surface. Theoretical results show that Rh atoms can occupy both sites simultaneously, or only Ti sites, or Ba sites. The electronic structure was modeled for two conditions. When Rh atoms occupy one Ba position and one Ti position, the electronic structure shows the presence of an acceptor level within the band gap above the Fermi level, effectively reducing the band gap of the material.
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ELECTRONIC STRUCTURE, MAGNETIC PROPERTIES AND STABILITY OF HEUSLER ALLOYS Mn2Co1−x VxZ (Z = Al, Ga)
(2020-12-30)
Fatima U. Abuova
;
Талгат Муратович Инербаев
;
Aisulu U. Abuova
;
G. A. Kaptagay
;
N. A. Merali
Two sets of Heusler alloys of the type Mn2Co1−xVxZ (Z = Al, Ga) were studied by computer simulation methods using density functional theory. Changes in the absolute value and direction of the lattice ions' magnetic moments are investigated depending on the chemical composition. Topological analysis of the charge distribution on the crystal lattice atoms is carried out to explain the results obtained. It is shown that changes in the magnetic properties are determined by the system's charge ions' states. The fundamental difference between Al- and Ga-containing alloys is Ga ions' ability, in contrast to Al ions, to change their charge state as the vanadium concentration increases, which gives an additional degree of freedom for modifying the electronic structure of the studied compounds.
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PRODUCTION OF MICROCRYSTALLINE CELLULOSE FROM AGRICULTURAL WASTE AND PREPARATION OF GEL FILMS BASED ON IT
(2025-10-22)
M. K. Shamshidenov
;
Yerkebulan A. Altynov
;
B. U. Rakhimova
;
Kalampyr Bexeitova
;
A. Seithan
This paper discusses the process of obtaining microcrystalline cellulose by removing lignin from biomass and studying its properties. Rice husks, which are agricultural waste, were used as biomass. The effect of the ratio of biomass to peroxyacetic acid on the yield of microcrystalline cellulose was determined. The yield of microcrystalline cellulose from rice husks at a ratio of 1/14 was 70%. Additionally, gel films based on rice MCC and sodium alginate were prepared, and their hydrolytic degradation properties were studied. In an acidic medium (pH 4.08), the gel film showed a 66% mass loss within 7 days, indicating pH sensitivity and biodegradability. The morphological surface, average particle size, and structure of the samples were studied. The surface morphology of the samples was examined using a scanning electron microscope, and it was found that the average particle size was 7–10 µm. X-ray diffraction (XRD) analysis confirmed the amorphous–crystalline nature of the material. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of hydroxyl, carbonyl, and ether functional groups. Thermogravimetric analysis (TGA) demonstrated the thermal stability of the gel films. The developed method for producing microcrystalline cellulose from biomass requires fewer processing stages compared to traditional methods and is environmentally safe. It was shown that high-quality microcrystalline cellulose can be obtained in one stage without the use of reagents containing sulfur and chlorine, high pressure, or large amounts of water. The interest in microcrystalline cellulose is due to its unique properties, such as lightness, non-toxicity, biocompatibility, and biodegradability. Currently, it is in high demand in the production of aerogels, gels, biocomposites, biodegradable materials, and films.
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EFFECT OF Rh-DOPING ON THE OPTICAL ABSORPTION OF THE (001) BaTiO3 SURFACE
(2024-06-30)
Zh. Ye. Zakiyeva
;
Talgat M. Inerbaev
;
Aisulu U. Abuova
;
Fatima U. Abuova
;
S. A. Nurkenov
Barium titanate is one of the most studied perovskite materials due to its substitution ability at both nodes of the crystal lattice, high dielectric constant, and stability. It has many outstanding characteristics, especially ferroelectric and dielectric properties, which can be improved by alloying, making this material suitable for a wide range of applications. In this paper, the effect of Rh doping on the structural, optical properties and electronic density of states of this compound is investigated. According to our calculations, Rh doping is a method that helps to increase the ability of BaTiO3 to absorb more light and reduce the excess potential required for water oxidation. Calculations of the electronic density of states were carried out using the hybrid functional HSE06. The analysis of optical properties was performed on the basis of matrix elements with a transient dipole moment. Studies have confirmed that the (001) BaTiO3 surface with terminated TiO2 has significant potential for use as a catalyst. Rh doping leads to an expansion of the spectrum of absorbed light over the entire visible range.
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AB-INITIO CALCULATIONS OF RHOMBOHEDRAL BaTiO3 (111) SURFACE COMBINED WITH GRAPHENE FILMS
(2023-12-29)
B. M. Satanova
;
G. A. Kaptagay
;
A. P. Zharkymbekova
;
Fatima U. Abuova
;
Aisulu U. Abuova
Thin films of ABO3 perovskite ferroelectrics are important for many industrial applications, i.e., high-capacity memory cells, catalysis, optical waveguides, and integrated optics. The use of BaTiO3 for these industries and products is due to the variety of its surface structure and, accordingly, its electronic and chemical properties. Calculations of the surface characteristics of BaTiO3 from the first principles are useful for understanding processes that play a crucial role, such as surface reaction chemistry, surface phenomena, and adsorption surfaces. This study examined theoretical calculations related to the relaxed atomic structures of the surface of BaTiO3 (111).
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Erratum to: «OPTICAL PROPERTIES OF LOW-DIMENSIONAL SYSTEMS: METHODS OF THEORETICAL STUDY OF 2D MATERIALS»
(2024-09-30)
G. A. Kaptagay
;
B. M. Satanova
;
Fatima U. Abuova
;
N. O. Koilyk
;
Aisulu U. Abuova
.
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«AB-INITIO CALCULATIONS OF RHOMBOHEDRAL BaTiO3 (111) SURFACE COMBINED WITH GRAPHENE FILMS»
(2024-09-30)
B. M. Satanova
;
G. A. Kaptagay
;
A. P. Zharkymbekova
;
Fatima U. Abuova
;
Aisulu U. Abuova
.
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NEW NANOSTRUCTURED MATERIAL OBTAINED BY THE METHOD OF TEMPLATE SYNTHESIS
(2024-06-30)
Aiman Akylbekovа
;
Gulnaz Sarsekhan
;
Assyl-Dastan B. Bazarbek
;
Gulnara M. Aralbayeva
;
Diana Junisbekova
The article presents the results of an experimental study of zinc diselenide nanocrystals obtained by chemical deposition, which is the simplest method in the a-SiO2/Si-n track matrix. A sample of the SiO2/Si track was obtained by irradiation with Xe ions with an energy of 200 MeV (F = 108 ions/cm2) on a DC-60 cyclotron (Astana, Kazakhstan) followed by chemical treatment with fluoric acid (HF) in an aqueous solution. Before chemical treatment, ultrasonic cleaning of the sample surface with isopropanol was performed for 15 minutes (6.SB25-12DTS). After treatment, the samples were washed with deionized water (18.2 MOm). The chemical deposition of the track template was carried out at room temperature for 60 minutes. A solution consisting of zinc chloride and Selenium dioxide (ZnCl2 – 3.4 g/l, SeO2 – 0.2 g/l) was used as the electrolyte. The surface of the samples after deposition was examined using a Hitachi S-4800 scanning electron microscope (SEM). Morphological analysis showed that the degree of filling of nanopores varies depending on temperature. X-ray diffraction analysis (XRD) was performed using the D8 ADVANCE ECO X-ray diffractometer. According to X-ray diffraction analysis, the chemical deposition of zinc in the a-SiO2/Si-n trace matrix led to the formation of ZnSe2O5 nanocrystals with an orthorhombic crystal structure. The experimental parameters of the crystal lattice, crystal density, effective charge and chemical bond population are in good agreement with the results of quantum chemical calculations and other literature data performed in the approximation of linear combinations of atomic orbitals. Nonempirical calculations have shown that ZnSe2O5 has a direct range at the G point, and the calculated effective charges of atoms demonstrate a significant covalent contribution to chemical bonds forming mixed ionic covalent bonds. Photoluminescence (PL) was measured by excitation with light with a wavelength of 300 nm in the room temperature. The PL spectra were considered as a symbiosis of luminescence of zinc oxide and zinc selenide. The PL spectrum of chemically deposited samples consists of a wide band in the wavelength range from 2.6 to 3.2 eV at room temperature.
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DEVELOPMENT OF TECHNOLOGY FOR OBTAINING A BIODEGRADABLE POLYMER
(2023-10-07)
K. Sh. Shynzhyrbai
;
Сейтхан Азат
;
Mukhametkali Musagalievich Mataev
;
Ulan Zhantikeyev
;
Kainaubek Toshtay
An important technological solution for plastic pollution is the replacement of traditional biodegradable polymers, biodegradable polymer materials with physico-mechanical properties that cause environmental pollution. An urgent problem is the search for ways to reduce the self-decomposition of biopolymers and waste, as well as to reduce the cost of such materials, including the use for these purposes of substances that can be analogues of biodegradable polymers. The research work is aimed at obtaining a biodegradable biopolymer based on starch raw materials in the presence of various organic acids (citric acid, acetic acid, lactic acid) and plasticizers (glycerin, polyvinyl alcohol, nanomaterial). An effective material was selected from the products obtained from various acids and plasticizers. Measures to improve the technology of bioplastics production are considered. A durable and economical biopolymer capable of processing and biodegrading biological waste, including starch-containing garbage, has been obtained. The resulting products have successfully passed all physico-chemical tests and are ready for mass production. A scanning electron microscope and thermogravimetric analysis with IR spectroscopy were used to study the physicochemical parameters of the obtained biopolymers.
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