BULLETIN OF THE L.N. GUMILYOV EURASIAN NATIONAL UNIVERSITY. PHYSICS. ASTRONOMY SERIES

Study of thermally induced diffusion mechanisms of implanted helium in the near-surface layers of ceramics based on lithium metazirconate

Artem Kozlovskiy — Tue, 25 Mar 2025 00:00:00 +0000

The aim of this study is to determine the thermal exposure effect on the destruction processes of of near-surface layers of ceramics based on lithium metazirconate associated with the diffusion of implanted helium, alongside to determine the effect of the magnesium oxide dopant in low concentrations on restraining diffusion mechanisms during high-temperature irradiation. Interest in this type of ceramics is primarily due to the possibility of expanding the types of lithium-containing ceramics for the production and accumulation of tritium, as well as an increase in stability to degradation processes characteristic of high-temperature operating modes, alongside the accumulation of fission products of nuclear reactions of neutrons with lithium in the form of helium. According to studies carried out using the depth nanoindentation method (measurements along the trajectory of ion movement on a side cleavage), it was found that an elevation in the irradiation temperature leads to a rise in the thickness of the damaged layer, the alteration in which is due to the effects of helium diffusion into depth due to thermal effects. The softening of the near-surface layer during high-temperature irradiation is due to structural changes associated with a growth in deformation distortion of the crystal structure and its swelling, which is most pronounced during high-dose irradiation. At the same time, alterations in the structural features of lithium metazirconate due to the dopant concentration growth during the synthesis of lithium-containing ceramics leads not only to an increase in resistance to softening of the damaged layer, but also to a reduction in the thickness of the diffusion layer in ceramics under high-temperature irradiation.

Effect of strontium doping on structural and electrical conductivity of BaTi0.8Zr0.2O3-δ cathode materials for solid oxide fuel cell

Dr, Prof. — Tue, 25 Mar 2025 00:00:00 +0000

Cathode materials are crucial for the efficient operation of solid oxide fuel cell (SOFC), serving as a key component for the oxygen reduction reaction (ORR). Cobalt-containing cathode materials have shown good performance in terms of electronic conductivity and ORR kinetics. However, they suffer from significant drawbacks, including high cost, and instability at the high operating temperatures of SOFC. Thus, there is an increasing need to investigate cobalt-free alternatives that can overcome these limitations and enhance the overall performance and durability of SOFC. In this study, cobalt-free Ba_1-xSr_xTi_0.8Zr_0.2O_3-δ (BSTZ0, BSTZ25, and BSTZ50; x = 0, 0.25, 0.5) cathode materials were synthesized via traditional solid-state reaction techniques. The synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), to analyse their structural properties, and surface morphology. Electrical conductivity of the synthesised materials measured in air revealed promising results, with BSTZ0, BSTZ25, and BSTZ50 exhibiting conductivities of 18.2 S/cm, 19.5 S/cm, and 22.6 S/cm, respectively. X-ray diffraction analysis confirmed that all compositions crystallize in the tetragonal P4/mmm space group. Findings from this investigation indicate that the synthesized Sr-doped BaTi_0.8Zr_0.2O_3-δ materials exhibit excellent thermal stability and are promising candidates for SOFC cathodes.

On determining invariants of a three-dimensional elasticity tensor in anisotropic media

Tue, 25 Mar 2025 00:00:00 +0000

Invariants of elasticity tensors embody the most important mechanical properties of materials, effectively generalizing and extending the traditional concept of "spring stiffness" to much more complex, multidimensional systems. Unlike simple springs, where the stiffness is characterized by a single constant, elasticity tensors allow us to describe complex interactions in materials with anisotropic properties, including materials with different types of symmetry. These invariants are a powerful tool for analyzing and classifying mechanical properties, since they allow us to consider both linear and nonlinear responses of materials to external influences. In this paper, we use the generalized Kelvin representation to parameterize the stress tensor, which significantly simplifies and makes more visual the process of determining the influence of various factors on the elasticity tensor. In this study, we calculate the invariants of the anisotropic elasticity tensor, taking into account the rotational symmetry defined by the SO(3) group. As a result of the analysis, we identified 18 independent invariants, including 5 first-order invariants, especially relevant for isotropic materials, and 13 higher-order invariants. These results highlight the importance and complexity of studying anisotropic materials and open up new perspectives for their mechanical interpretation and classification.

The electronic structure and interstitial interactions of β-Ga2O3: an analysis of the MNDO method

Tue, 25 Mar 2025 00:00:00 +0000

This work investigates the behavior of interstitial gallium (Ga) atoms in the β-Ga₂O₃ crystal lattice using a semi-empirical approach with the HyperChem program. The study focuses on simulating different charge states of the interstitial Ga atom: Ga³⁺, Ga²⁺, Ga⁺, and the neutral Ga⁰ state. The modeling considers transitional processes under radiation exposure, where the Ga atom can capture electrons, transitioning between different charge states. Additionally, the scenario of a vacant lattice site capturing an electron, influenced by β-radiation, is examined. The obtained data allow for the analysis of changes in the electronic structure and local deformations around the interstitial atom during various charge states. This research provides deeper insights into defect behavior in β-Ga₂O₃ under radiation and its impact on the material's electronic properties.

Қышқыл ортадағы аса жоғары молекулалы полиэтилен негізіндегі композиттің микроқұрылымы

Молдир Баяндинова — Tue, 25 Mar 2025 00:00:00 +0000

In this paper, the effect of an acidic environment on the structure of composite coatings based on supermolecular polyethylene (AJMPE) modified with a mineral filler in the form of diabase is investigated. It has been found that the introduction of 10% diabase into the AZHMPE matrix significantly increases the resistance of the composite coating to a corrosive environment, which is confirmed by the minimum level of swelling compared with composites with a high content of pure AZHMPE and filler.
Scanning electron microscopy (SEM) showed a uniform distribution of diabase in the coating structure and the absence of defects such as sintering and cracks. Methods of infrared spectroscopy (AFS) and X-ray diffraction analysis (XRD) revealed a decrease in the degree of crystallinity of coatings under the action of acids, but no significant changes in the chemical structure of materials were recorded, which confirms their resistance to chemical decomposition.
Composites containing 10% diabase showed better chemical resistance, which is associated with the formation of a barrier structure that prevents the diffusion of acids. The results obtained indicate the prospect of using AGMPE with diabase filler to create coatings resistant to aggressive environments.

Methodology of high-temperature analysis of material properties under high pressure conditions for studying the sorption properties of materials

Нурсултан Айдарбеков, Kenzhebatyr Bekmyrza — Tue, 25 Mar 2025 00:00:00 +0000

This article presents a methodology for applying high-pressure high-temperature volumetric analysis (HPVA) to investigate the sorption properties of a wide range of materials. The HPVA method enables precise measurement of gas adsorption and desorption (e.g., hydrogen, carbon dioxide, or hydrocarbon mixtures) under various temperature and pressure regimes, including both standard
and extreme conditions. Such measurements are critically important for evaluating materials used in advanced fields such as hydrogen storage, carbon dioxide capture and processing, and catalytic chemical reactions. The application of HPVA provides quantitative data on sorption capacity, as well as information under conditions closely approximating the actual kinetics of gas molecules interacting with the surface and internal pores of the materials. The article thoroughly examines key stages of the HPVA methodology:
the preliminary degassing and moisture removal process, including the preparation of samples for experimental analysis; the setup and calibration of equipment under high-temperature and highpressure conditions; and the data processing algorithms that make it possible to determine fundamental parameters of porous structures (pore volume, pore size distribution, sorption capacity). The results obtained have practical significance for the development of novel high-performance sorbents, catalysts,
and nanostructured materials for energy resource storage, thereby further expanding opportunities for creating environmentally friendly and economically viable technologies.

The prospects of studying ternary nuclear fission in horizontal channel No. 1 of the VVR-K reactor.

Данияр Бериков — Tue, 25 Mar 2025 00:00:00 +0000

The article discusses the study of rare nuclear fission mechanisms, such as ternary and quaternary fission, which occur during both spontaneous and induced fission by neutrons. Our group previously conducted experiments to investigate the ternary and quaternary spontaneous fission of the isotope ²⁵²Cf. The next stage is to study ternary fission during induced fission by neutrons.

Steps have been prepared for conducting research on ternary fission under neutron irradiation, including the creation of an experimental setup and the development of particle detection methods. Test measurements were carried out at the VVR-K reactor in Almaty. Experiments with the ²³⁹Pu target provided valuable methodological results that significantly impact the accuracy of subsequent studies. The conclusions of the experiment confirm the need to revise technical solutions to achieve high standards of accuracy and reliability in research.

Өлшеу технологиясындағы оптикалық сенсорлар: деформация мен температураны бақылауға арналған қолданбалар

sauletbek koshkinbaev — Tue, 25 Mar 2025 00:00:00 +0000

In the modern world, optical sensors are increasingly used in measurement technology due to their high sensitivity, accuracy, and resistance to external influences. The purpose of this study is to analyze the possibilities of using optical sensors for deformation and temperature control in various industries and scientific research. The work considers the main directions of development and improvement of measurement technologies using optical sensors.

The research methodology includes experimental testing of fiber-optic sensors with Bragg gratings, as well as modeling their operation under conditions of increased load and temperature fluctuations. The main results include analysis of measurement accuracy, assessment of the sensitivity of sensors to external changes, and determination of their durability.

The data obtained show that optical sensors can effectively replace traditional measurement systems, providing high accuracy and reliability. The practical significance of the study lies in the development of recommendations for the use of optical sensors for monitoring the condition of structures, energy facilities, and medical devices. It makes a significant contribution to the development of measurement technologies, helping to increase the efficiency and reliability of work.

Study of structural and morphological properties of powders and thin films of samaria doped cerium oxide

Сапарғали Пазылбек — Tue, 25 Mar 2025 00:00:00 +0000

An analysis of 26% samarium doped ceria (SDC) powders and thin films for solid oxide fuel cells (SOFCs) is considered. Glycine-nitrate combustion (CB), co-precipitation (CP), and aqueous sol-gel (SG) methods are used in the preparation of SDC powders and thin films, and methods for analyzing the obtained samples are described. All obtained powders were heated from 200 to 1000℃ degrees , showing that the crystal structure of cerium activated by samarium develops at very high temperatures. It shows that the lattice parameter and crystallite size of the heated powders increase with increasing heating temperature, and the lattice parameter is higher than the theoretical values.

The results of the experiment revealed that the average size of the crystallites of thin films increases with the increase in thickness. Among the applied syntheses, the CB method is considered to have better results compared to co-precipitation and sol-gel methods. The experimental values of the lattice parameter of the thin films deposited on the SiO₂ mat were higher than the theoretical value. As the thickness increases, the average crystallite size of the thin films deposited on the SiO₂ substrate increases. The results of the atomic force microscope showed that the average values of the surface roughness of thin films increase with the increase in thickness. The mean surface roughness (R_s), root mean square roughness (R_q), kurtosis (R_ku), skewness (R_sk) were characterized using appropriate software.

INVESTIGATION OF TIN-LITHIUM ALLOY BEHAVIOR IN HIGH-TEMPERATURE HYDROGEN ISOTOPE ENVIRONMENTS: SORPTION AND DESORPTION ANALYSIS

Artem Kozlovskiy — Tue, 25 Mar 2025 00:00:00 +0000

Nuclear fusion's effectiveness relies heavily on managing the intense power loads that strike the first wall, especially the divertor in plasma-physical devices. Due to their self-regulating liquid surfaces, liquid metals, such as lithium and tin, present a promising alternative to solid plasma-facing materials. A promising candidate is a tin-lithium alloy, which is expected to combine the beneficial properties of its constituent metals. The present study investigates tin-lithium alloy's sorption and desorption characteristics when exposed to hydrogen isotopes under high-thermal stress conditions. Specifically, experiments were conducted using a Sn₇₃Li₂₇ alloy with adsorption and thermally stimulated desorption (TDS) techniques employed to characterize its behavior. The sorption experiments were performed under high-temperature conditions from 450°C to 600°C and at different values of residual deuterium pressure in the device volume. The TDS experiments involved measuring the gas flows released from the tin-lithium alloy into the evacuated chamber under linear heating conditions. The temperature dependence of the effective deuterium solubility constant in the alloy was calculated, revealing the complexity of the interaction mechanisms influenced by experimental conditions. The results provide insights into the interaction dynamics between the tin-lithium alloy and hydrogen isotopes, underlining the material’s performance and stability in high-temperature environments.

Application of track detectors to measure radon and thoron activity in the environment: a review of methods and results

Жанат Насилов, Kassym Zhumadilov — Tue, 25 Mar 2025 00:00:00 +0000

This paper presents an overview of the application of track detectors for measuring radon
and thoron activity in various environments. The study covers the key aspects of the method: operating
principles, detector types (CR-39, LR-115, Radon Eye Plus2, SSNTD), exposure conditions and analysis
methods. Modern studies, including measurements of radon activity in residential premises, mines,
caves, water and soil, as well as the influence of various geological and climatic factors on measurements
are considered. It is shown that CR-39 has high sensitivity to low radon concentrations, which makes
it preferable for detailed studies of low pollution levels, while LR-115 is more effective for long-term
monitoring due to its resistance to external influences. Particular attention is paid to the influence of
environmental parameters (temperature, humidity, pressure) and calibration methods on the accuracy of the results. Current problems associated with data interpretation , including errors due to track etching
methods and visualization of results are considered. The need for standardization of measurement
methods and prospects for automation of analysis processes using digital technologies are emphasized.
The results of the work can be used in developing radiation safety strategies, monitoring radon levels in
residential and industrial areas, and in environmental monitoring. Recommendations are proposed for
the optimal use of track detectors for assessing radiation risks and developing more effective methods
for detecting radon in various environments.

Study of carbon admixture to oxygen adsorption on the surface of ВаТіО3 (001) from the first principles

Balzhan Satanova — Tue, 25 Mar 2025 00:00:00 +0000

Solid-state thin-film photovoltaic technologies are promising for converting solar energy into electrical energy to meet the energy needs of the global economy. New thin-film solar cells such as organic solar cells, dye-coated solar cells, and perovskite solar cells have become effective approaches to their design. Such functional materials must be competitive with established technologies such as
silicon solar cells, in addition to the simplicity of their application methods and lower production costs in their design, as well as energy conversion efficiency. Thin-film technology is currently one of the main directions in photovoltaic film research due to the impressive performance growth over several years of research. Various approaches have been used to ensure long-term operation and increase the energy efficiency of perovskite solar cells. For the sustainable functioning of solar cells, doping of the carbon base with elements is the most effective.
The paper investigates the catalytic role of a carbon dopant on the surface of BaTiO3 in the theoretical combination of the density functional theory method with the pseudopotential method in the basis of plane waves. Based on the theory of the density functional, the process of adsorption of atomic and molecular oxygen on the TiO2
-terminated (001) surface of barium titanate of in the tetragonal phase, which was pure and doped with carbon atoms, was investigated. The most effective places for carbon adsorption on the TiO2 terminated (001) surface were the positions of the “Ti atop”. On a clean surface,
the adsorption energy was -0.5 eV for atomic oxygen adsorbed near the energy efficient site defined for carbon, and -2.12 eV for molecular oxygen. For atomic oxygen adsorbed on a carbon-doped surface, the adsorption energy decreased by -0.2 eV, and for molecular oxygen by -0.4 eV