Study of the Influence of the Irradiation Flux Density on the Formation of a Defect Structure in AlN in the Case of the Effect of Overlapping of the Heavy Ion Motion Trajectories in the Near-Surface Layer

This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. AP14972854). Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.The aim of this paper is to test the previously stated hypothesis and several experimental facts about the effect of the ion flux or ion beam current under irradiation with heavy ions on the radiation damage formation in the ceramic near-surface layer and their concentration. The hypothesis is that, when considering the possibilities of using ion irradiation (usually with heavy ions) for radiation damage simulation at a given depth, comparable to neutron irradiation, it is necessary to consider the rate factor for the set of atomic displacements and their accumulation. Using the methods of X-ray diffraction analysis, Raman and UV–Vis spectroscopy, alongside photoluminescence, the mechanisms of defect formation in the damaged layer were studied by varying the current of the Xe23+ ion beam with an energy of 230 MeV. As a result of the experimental data obtained, it was found that, with the ion beam current elevation upon the irradiation of nitride ceramics (AlN) with heavy Xe23+ ions, structural changes have a pronounced dependence on the damage accumulation rate. At the same time, the variation of the ion beam current affects the main mechanisms of defect formation in the near-surface layer. It has been found that at high values of flux ions, the dominant mechanism in damage to the surface layer is the mechanism of the formation of vacancy defects associated with the replacement of nitrogen atoms by oxygen atoms, as well as the formation of ON–VAl complexes. © 2023 by the authors. --//-- Bikhert Y.V., Kozlovskiy A.L., Popov A.I., Zdorovets M.V.; Study of the Influence of the Irradiation Flux Density on the Formation of a Defect Structure in AlN in the Case of the Effect of Overlapping of the Heavy Ion Motion Trajectories in the Near-Surface Layer; (2023) Materials, 16 (15), art. no. 5225; DOI: 10.3390/ma16155225; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85167788062&doi=10.3390%2fma16155225&partnerID=40&md5=8456d5572e735de9d929ce9191431926. Published under the CC BY 4.0 licence.This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. AP14972854). Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2

Investigation of the Effect of PbO Doping on Telluride Glass Ceramics as a Potential Material for Gamma Radiation Shielding

This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. BR11765580). In addition, A.I.P. thanks the Institute of Solid-State Physics, University of Latvia. ISSP UL as the Center of Excellence is supported through the Framework Program for European universities, Union Horizon 2020, H2020-WIDESPREAD-01–2016–2017-TeamingPhase2, under Grant Agreement No. 739508, CAMART2 project.The purpose of this paper is to study the effect of PbO doping of multicomponent composite glass-like ceramics based on TeO2, WO3, Bi2O3, MoO3, and SiO2, which are one of the promising materials for gamma radiation shielding. According to X-ray diffraction data, it was found that the PbO dopant concentration increase from 0.10 to 0.20–0.25 mol results in the initialization of the phase transformation and structural ordering processes, which are expressed in the formation of SiO2 and PbWO4 phases, and the crystallinity degree growth. An analysis of the optical properties showed that a change in the ratio of the contributions of the amorphous and ordered fractions leads to the optical density increase and the band gap alteration, as well as a variation in the optical characteristics. During the study of the strength and mechanical properties of the synthesized ceramics, depending on the dopant concentration, it was found that when inclusions in the form of PbWO4 are formed in the structure, the strength characteristics increase by 70–80% compared to the initial data, which indicates the doping efficiency and a rise in the mechanical strength of ceramics to external influences. During evaluation of the shielding protective characteristics of the synthesized ceramics, it was revealed that the formation of PbWO4 in the structure results in a rise in the high-energy gamma ray absorption efficiency. © 2023 by the authors.--//-- This is an open access article Kozlovskiy A.L., Shlimas D.I., Zdorovets M.V., Elsts E., Konuhova M., Popov A.I.; Investigation of the Effect of PbO Doping on Telluride Glass Ceramics as a Potential Material for Gamma Radiation Shielding (2023) Materials, 16 (6), art. no. 2366; DOI: 10.3390/ma16062366; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85152065176&doi=10.3390%2fma16062366&partnerID=40&md5=34067687ddfd88cbc2bd3e23cbedeb27 published under the CC BY 4.0 licence.Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. BR11765580); the Institute of Solid-State Physics, University of Latvia. ISSP UL as the Center of Excellence is supported through the Framework Program for European universities, Union Horizon 2020, H2020-WIDESPREAD-01–2016–2017-TeamingPhase2, under Grant Agreement No. 739508, CAMART2 project

Study of helium swelling and embrittlement mechanisms in SiC ceramics

This work is devoted to the study of the radiation damage kinetics and subsequent embrittlement of the near-surface layer of SiC ceramics subjected to irradiation with low-energy He2+ ions. Interest in these types of ceramics is due to their great prospects for use as structural materials for nuclear power, as well as for use in the creation of protective structures for longterm storage of spent nuclear fuel. During the study, the dependences of changes in the structural, mechanical,strength, and morphological characteristics of SiC ceramics depending on irradiation fluence were obtained. It has been established that the greatest changes in the strength properties are associated with the dominance of the crystal lattice swelling effect in the structure due to an increase in the concentration of implanted helium, and its further agglomeration with the formation of vacancy complexes of the He-V type. A model for changing the structural properties of ceramics irradiated with low-energy He2+ ions based on the change in the contributions of the dislocation density concentration, anisotropic distortion of the crystal lattice, and the effect of swelling as a result of implantation is proposed

Morphology and Microstructure Evolution of Gold Nanostructures in the Limited Volume Porous Matrices

The modern development of nanotechnology requires the discovery of simple approaches that ensure the controlled formation of functional nanostructures with a predetermined morphology. One of the simplest approaches is the self-assembly of nanostructures. The widespread implementation of self-assembly is limited by the complexity of controlled processes in a large volume where, due to the temperature, ion concentration, and other thermodynamics factors, local changes in diffusion-limited processes may occur, leading to unexpected nanostructure growth. The easiest ways to control the diffusion-limited processes are spatial limitation and localized growth of nanostructures in a porous matrix. In this paper, we propose to apply the method of controlled self-assembly of gold nanostructures in a limited pore volume of a silicon oxide matrix with submicron pore sizes. A detailed study of achieved gold nanostructures' morphology, microstructure, and surface composition at different formation stages is carried out to understand the peculiarities of realized nanostructures. Based on the obtained results, a mechanism for the growth of gold nanostructures in a limited volume, which can be used for the controlled formation of nanostructures with a predetermined geometry and composition, has been proposed. The results observed in the present study can be useful for the design of plasmonic-active surfaces for surface-enhanced Raman spectroscopy-based detection of ultra-low concentration of different chemical or biological analytes, where the size of the localized gold nanostructures is comparable with the spot area of the focused laser beam

Phase Transformations and Photocatalytic Activity of Nanostructured Y2O3/TiO2-Y2TiO5 Ceramic Such as Doped with Carbon Nanotubes

This work is devoted to the study of phase transition processes in nanostructured ceramics of the Y2O3/TiO2-Y2TiO5 type doped with carbon nanotubes as a result of thermal annealing, as well as to the assessment of the prospects of the effect of phase composition on photocatalytic activity. By the method of X-ray phase analysis, it was found that an increase in the annealing temperature leads to the formation of the orthorhombic phase Y2TiO5, as well as structural ordering. Based on the obtained UV spectra, the band gap was calculated, which varies from 2.9 eV (initial sample) to 2.1 eV (annealed at a temperature of 1000 °C). During photocatalytic tests, it was established that the synthesized nanostructured ceramics Y2O3/TiO2-Y2TiO5 doped CNTs show a fairly good photocatalytic activity in the range of 60–90% decomposition of methyl orange

Study of Structural, Strength, and Thermophysical Properties of Li2+4xZr4−xO3 Ceramics

The work is devoted to the study of technology that can be used to obtain lithium-containing ceramics of the Li2+4xZr4−xO3 type using the method of solid-phase synthesis combined with thermal annealing at a temperature of 1500 °C. A distinctive feature of this work is the preparation of pure Li2ZrO3 ceramics with a high structural ordering degree (more than 88%) and density (95–97% of the theoretical density). During the study, it was found that a change in the content of initial components for synthesis does not lead to the formation of new phase inclusions; however, an increase in the LiClO4·3H2O and ZrO2 components leads to changes in the size of crystallites and dislocation density, which lead to the strengthening of ceramics to external mechanical influences. The results of the measurements of thermophysical characteristics made it possible to establish that the compaction of ceramics and a decrease in porosity lead to an increase in the thermal conductivity coefficient of 3–7%

Study of Polymorphic Transformation Processes and Their Influence in Polycrystalline ZrO2 Ceramics upon Irradiation with Heavy Ions

The aim of this work was to study the mechanisms of polymorphic transformations in ZrO2 ceramics under irradiation with heavy ions, as well as to determine the nature of structural distortions in the case of t-ZrO2 → c-ZrO2 type transformations and associated anisotropic deformations. The samples of ZrO2 ceramics were irradiated with Kr15+ heavy ions with an energy of 150 MeV and fluences of 1011–1016 ion/cm2. During evaluation of the structural changes depending on the irradiation fluence, it was found that at low irradiation fluences (1011–1012 ion/cm2), the main role is played by deformation distortions of the crystal lattice, which have a pronounced anisotropic character. Meanwhile, at fluences above 1013 ion/cm2, the main role is played by polymorphic transformations of the t-ZrO2 → c-ZrO2 type, followed by amorphization of the damaged layer at fluences above 1015 ion/cm2. It was established that the anisotropic distortion of the crystal lattice is more pronounced along the crystallographic a axis, as well as the (011) texture orientation, which is characteristic of t-ZrO2. The polymorphic transformation processes of the t-ZrO2 → c-ZrO2 type occur at irradiation fluences of 1013–1014 ions/cm2, which are characterized by the formation of an overlap of local areas of defects that appear along the trajectory of ions in the material. The dependences of changes in the strength and thermophysical properties of ZrO2 ceramics on the irradiation fluence were obtained. The mechanisms of influence of the structural disorder and polymorphic transformations on the decrease in strength and crack resistance were established

Study of the Morphological and Structural Features of Inert Matrices Based on ZrO2–CeO2 Doped with Y2O3 and the Effect of Grain Sizes on the Strength Properties of Ceramics

This article is devoted to the study of the mechanical and strength properties of Y2O3-doped ZrO2–CeO2 composite ceramics. The choice of these ceramics is due to their prospects in the field of nuclear energy, structural materials and as the basis for materials of dispersed nuclear fuel inert matrices. The choice as objects for research is due to their physicochemical, insulating and strength properties, the combination of which makes it possible to create one of the promising types of composite ceramics with high resistance to external influences, high mechanical pressures and crack resistance. The method of mechanochemical synthesis followed by thermal annealing of the samples at a temperature of 1500 °C; was used as a preparation method; to study the effect of Y22O3 doping, scanning electron microscopy methods were used to determine morphological features. The X-ray diffraction method was applied to determine the structural features and phase composition. The mechanical methods of microindentation and single compression for determination were applied to determine the strength characteristics. During the tests, it was found that the most resistant materials to external mechanical influences, and thermal heating for a long time of testing, are ceramics, in which the CeZrO4 phase dominates. At the same time, the strengthening of ceramics and an increase in crack resistance is due to a change in the phase composition and to a decrease in the grain size, leading to the formation of a large dislocation density, and, consequently, the appearance of the dislocation strengthening effect. The relevance and novelty of this study lies in obtaining new types of ceramic materials for inert matrices of nuclear fuel, studying their morphological, structural, strength and thermophysical properties, as well as assessing their resistance to external influences during prolonged thermal heating. The results obtained can later be used as fundamental knowledge in assessing the prospects for the use of oxide ceramics as nuclear materials

Study of the Morphological and Structural Features of Inert Matrices Based on ZrO₂–CeO₂ Doped with Y₂O₃ and the Effect of Grain Sizes on the Strength Properties of Ceramics

This article is devoted to the study of the mechanical and strength properties of Y2O3-doped ZrO2–CeO2 composite ceramics. The choice of these ceramics is due to their prospects in the field of nuclear energy, structural materials and as the basis for materials of dispersed nuclear fuel inert matrices. The choice as objects for research is due to their physicochemical, insulating and strength properties, the combination of which makes it possible to create one of the promising types of composite ceramics with high resistance to external influences, high mechanical pressures and crack resistance. The method of mechanochemical synthesis followed by thermal annealing of the samples at a temperature of 1500 °C; was used as a preparation method; to study the effect of Y22O3 doping, scanning electron microscopy methods were used to determine morphological features. The X-ray diffraction method was applied to determine the structural features and phase composition. The mechanical methods of microindentation and single compression for determination were applied to determine the strength characteristics. During the tests, it was found that the most resistant materials to external mechanical influences, and thermal heating for a long time of testing, are ceramics, in which the CeZrO4 phase dominates. At the same time, the strengthening of ceramics and an increase in crack resistance is due to a change in the phase composition and to a decrease in the grain size, leading to the formation of a large dislocation density, and, consequently, the appearance of the dislocation strengthening effect. The relevance and novelty of this study lies in obtaining new types of ceramic materials for inert matrices of nuclear fuel, studying their morphological, structural, strength and thermophysical properties, as well as assessing their resistance to external influences during prolonged thermal heating. The results obtained can later be used as fundamental knowledge in assessing the prospects for the use of oxide ceramics as nuclear materials