Dynamics of radiation damage in aln ceramics under high-dose irradiation, typical for the processes of swelling and hydrogenation

The use of nitride ceramics, in particular AlN, as structural materials for nuclear power is primarily limited by their resistance to swelling and hydrogenation processes due to the accumulation of poorly soluble helium and hydrogen ions in the structure of the surface layer. In this regard, research in this area is of great importance not only from a fundamental point of view, but also practical, since any new data on radiation resistance can make a great contribution to the development of the theory of resistance to radiation influences of structural materials of a new generation. This work is devoted to a systematic study and comparative analysis of the dynamics of radiation damage during high-dose irradiation with protons and helium ions in nitride ceramics, which have great potential for use as structural materials for GenIV reactors. The choice of irradiation doses of 1 × 1017 –5 × 1017 ion/cm2 is due to the possibility of modeling the processes of radiation damage characteristic of displacements of 10–50 dpa. During the study, the dependences of the change in the dielectric and conductive characteristics of nitride ceramics depending on the radiation dose, as well as on the type of ions, were established. The kinetics of degradation and accelerated aging was determined depending on the type of exposure. The mechanical and strength properties of ceramics were determined. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Republic of KazakhstanFunding: This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. AP08051975)

Evaluation of the Influence of Grain Sizes of Nanostructured WO3 Ceramics on the Resistance to Radiation-Induced Softening

The main purpose of this study is to test a hypothesis about the effect of grain size on the resistance to destruction and changes in the strength and mechanical properties of oxide ceramics subjected to irradiation. WO3 powders were chosen as objects of study, which have a number of unique properties that meet the requirements for their use as a basis for inert matrices of dispersed nuclear fuel. The grain-size variation in WO3 ceramics was investigated by mechanochemical grinding of powders with different grinding speeds. Grinding conditions were experimentally selected to obtain powders with a high degree of size homogeneity, which were used for further research. During evaluation of the strength properties, it was found that a decrease in the grain size leads to an increase in the crack resistance, as well as the hardness of ceramics. The increase in strength properties can be explained by an increase in the dislocation density and the volume contribution of grain boundaries, which lead to hardening and an increase in resistance. During determination of the radiation damage resistance, it was found that a decrease in grain size to 50–70 nm leads to a decrease in the degree of radiation damage and the preservation of the resistance of irradiated ceramics to destruction and cracking. © 2023 by the authors.Ministry of Education and Science of the Republic of Kazakhstan: AP13068156This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant AP13068156)

Structural and magnetic studies of FE100–xCox nanotubes obtaine by template method

Hollow nanostructures based on the Fe100–xCox alloy were synthesized in the pores of polymer template matrices based on PET using the electrochemical deposition method. Morphology, elemental composition, and structural features were characterized by scanning electron microscopy, energy dispersive analysis, and X-ray diffractometry. The study of the internal magnetic texture was carried out using Mossbauer spectroscopy. The dependence of the change in structural and magnetic properties from the atomic content of components in nanotube structure is revealed. It is established that the synthesized nanostructures are hollow Fe100–xCox nanotubes with a body-centered cubic crystal structure. The decrease in the unit cell parameter with increasing cobalt concentration is due to the difference in the radii of Fe (1.227 Å) and Co (1.191 Å) atoms. It is established that a random distribution of magnetic moments directions of Fe atoms is observed for Fe100Co0 nanotubes. And magnetic texture along the nanotube axis is observed for Fe100–xCox nanotubes, with an increase in Co atoms concentration. The average angle between the direction of the magnetic moment of iron atoms and the nanotube axis decreases from v = 54:6° to v = 24:5°. © 2018, Electromagnetics Academy. All rights reserved

Synthesis and Characterization of the Properties of (1−x)Si3N4-xAl2O3 Ceramics with Variation of the Components

The aim of this paper is to study the effect of variation in the component ratio of (1−x)Si3N4-xAl2O3 ceramics on the phase composition, strength and thermal properties of ceramics. To obtain ceramics and their further study, the solid-phase synthesis method combined with thermal annealing of samples at a temperature of 1500 °C typical for the initialization of phase transformation processes was used. The relevance and novelty of this study lies in obtaining new data on the processes of phase transformations with a variation in the composition of ceramics, as well as determining the effect of the phase composition on the resistance of ceramics to external influences. According to X-ray phase analysis data, it was found that an increase in the Si3N4 concentration in the composition of ceramics leads to a partial displacement of the tetragonal phase of SiO2 and Al2(SiO4)O and an increase in the contribution of Si3N4. Evaluation of the optical properties of the synthesized ceramics depending on the ratio of the components showed that the formation of the Si3N4 phase leads to an increase in the band gap and the absorbing ability of the ceramics due to the formation of additional absorption bands from 3.7–3.8 eV. Analysis of the strength dependences showed that an increase in the contribution of the Si3N4 phase with subsequent displacement of the oxide phases leads to a strengthening of the ceramic by more than 15–20%. At the same time, it was found that a change in the phase ratio leads to the hardening of ceramics, as well as an increase in crack resistance. © 2023 by the authors.Ministry of Education and Science of the Republic of Kazakhstan: AP14871176This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant AP14871176)

Synthesis, Properties and Photocatalytic Activity of CaTiO3-Based Ceramics Doped with Lanthanum

The aim of this work is to study the effect of lanthanum doping on the phase formation processes in ceramics based on CaTiO3, as well as to evaluate the effectiveness of the ceramics as photocatalysts for the decomposition of the organic dye Rhodamine B. The methods used were scanning electron microscopy to evaluate the morphological features of the synthesized ceramics, X-ray diffraction to determine the phase composition and structural parameters, and UV-Vis spectroscopy to determine the optical properties of the ceramics. During the experiments it was found that an increase in the lanthanum dopant concentration from 0.05 to 0.25 mol leads to the formation of the orthorhombic phase La0.3Ca0.7TiO3 and the displacement from the ceramic structure of the impurity phase TiO2, which presence is typical for the synthesized ceramics by solid-phase synthesis. On the basis of the data of the X-ray phase analysis the dynamics of phase transformations depending on concentration of lanthanum was established: CaTiO3/TiO2 → CaTiO3/La2TiO5 → CaTiO3/La0.3Ca0.7TiO3 → La0.3Ca0.7TiO3. During the determination of photocatalytic activity it was found that the formation of La0.3Ca0.7TiO3 phase leads to an increase in the decomposition rate as well as the degree of mineralization. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Republic of Kazakhstan: AP09259182Funding: This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. AP09259182)

Influence of deposition potential on structure of Zn-based nanotubes

The rapid growth of the market of electronic devices designed on the base of micro- and nanoelectronic components requires novel unconventional approaches for nanostructures formation. In this regard, ion-track technology, which allows forming nanostructures with a predetermined geometry is very promising. The paper demonstrates a simple and scalable approach to the creation of nanotubes based on pure zinc and its oxide. The main idea of the work is to determine the possibility of controlling of the nanotubes morphology and composition by variation of the deposition potential. In this concern, template synthesis of zincbased nanotubes in the PET template pores is carried out at potentials in the range from 1.25 to 2 V and a comprehensive study of their structural and morphological features is provided. © 2019 Elsevier Ltd

A Study on the Applicability of NiFe2O4 Nanoparticles as the Basis of Catalysts for the Purification of Aqueous Media from Pollutants

The aim of this work is to evaluate the application of NiFe2O4 nanoparticles with spinel structures as the basis of catalysts for the purification of aqueous media from pollutants such as manganese and arsenic. The interest in these catalysts is due to their ease of production and high absorption efficiency, which, together with their magnetic properties, allow the use of nanoparticles for a long time. The sol–gel method, followed by thermal annealing of the samples at different temperatures, was proposed as a method for the synthesis of spinel nanoparticles. The choice of the annealing temperature range of 200–1000◦C is caused by the possibility of estimating changes in the structural properties and the degree of nanoparticles crystallinity. During the study of structural changes in nanoparticles depending on the annealing temperature, it was found that in the temperature range of 200–800◦C, there is an ordering of structural parameters, while for samples obtained at annealing temperatures above 800◦C, there is a partial disorder caused by the agglomeration of nanoparticles with a subsequent increase in their size. According to the results of the studies on the purification of aqueous media from pollutants, it was found that the greatest absorption efficiency belongs to nanoparticles annealed at 500–700◦C, with the purification efficiency of 70–85%, depending on the type of pollutant. The results obtained from the use of nanoparticles as catalysts for the purification of aqueous media show great prospects for their further application on an industrial scale. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Study of Corrosion Mechanisms in Corrosive Media and Their Influence on the Absorption Capacity of Fe2O3/NdFeO3 Nanocomposites

This paper presents the results of a study of the change in the stability of Fe2O3/NdFeO3nanocomposites when exposed to aggressive media over a long period of time. The main purpose of these studies is to investigate the mechanisms of degradation and corrosion processes occurring in Fe2O3/NdFeO3nanocomposites, as well as the influence of the phase composition on the properties and degradation resistance. According to the X-ray phase analysis, it was found that the variation of the initial components leads to the formation of mixed composition nanocomposites with different Fe2O0/NdFeO3phase ratios. During corrosion tests, it was found that the dominance of the NdFeO3phase in the composition of nanocomposites leads to a decrease in the degradation and amorphization rate of nanostructures by a factor of 1.5–2 compared to structures in which the Fe2O3phase dominates. Such a difference in the degradation processes indicates the high stability of two-phase composites. Moreover, in the case of an aqueous medium, nanocomposites dominated by the NdFeO3phase are practically not subjected to corrosion and deterioration of properties. The results obtained helped to determine the resistance of Fe2O3/NdFeO3nanocomposites to degradation processes caused by exposure to aggressive media, as well as to determine the mechanisms of property changes in the process of degradation. The results of the study of the absorption capacity of Fe2O3/NdFeO3nanocomposites in the case of the purification of aqueous media from manganese and arsenic showed that a change in the phase ratio in nanocomposites leads to an increase in the absorption efficiency of pollutants from aqueous media. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Republic of Kazakhstan: AP09259184Funding: This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant AP09259184)

Investigation of the Prospects for the Use of Iron-Containing Nanocomposites Doped with Rare Earth Elements as Catalysts for the Purification of Aqueous Media

The great interest in nanostructured magnetic composites is due to their great prospects for use as a basis for the development of catalysts for the adsorption of manganese in wastewater. Interest in magnetic nanocomposites in this direction is primarily due to the possibility of extracting them from water media using ordinary magnets, which allows them to be used again. Additionally, it is worthwhile to note interest in research related to increasing the efficiency of adsorption, as well as an increase in the number of repeated cycles of operation. In this regard, the main goal of this study is to study the prospects for applying the method of mechanochemical synthesis for the creation of iron-containing nanocomposites doped by rare-earth elements Gd, Ce, Y, and Nd in order to obtain optimal catalysts for cleaning water media. During the studies, structural properties and phase composition of synthesized nanocomposites were established, as well as ultra-thin parameters of the magnetic field. It has been established that the kinetic curves of the adsorption process can be described by a pseudo-first-order model, and the process of manganese adsorption itself is associated with the cationic interaction of manganese ions with the surface of nanocomposites. The kinetic curves of degradation were determined, as well as the influence of the number of cyclic tests on the adsorption of manganese for synthesized nanocomposites, depending on the type of dopant and phase composition, respectively. Iron-containing nanocomposites doped with gadolinium and neodymium have been found to have the highest adsorption efficiency and corrosion resistance. Particular attention is paid to the study of the stability of storage of nanocomposites for a long time, as well as the preservation of their adsorbent properties in the purification of aqueous media. It has been determined that the modification of nanostructures with the help of rare earth compounds leads to an increase in resistance to degradation, as well as to the preservation of the efficiency of adsorption for 5–7 cycles in comparison with Fe2O3 nanoparticles, for which low resistance to degradation was observed. © 2023 by the authors.Ministry of Education and Science of the Republic of Kazakhstan: AP09259184This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant AP09259184)

Optimization of PET ion-track membranes parameters

Nowadays polymer ion-track membranes are used for a wide range of practical applications, which include various levels of filtration (micro-, ultra-, nanofiltration and osmosis), the creation of flexible electronic circuits and sensors based on polymer substrate, and using as templates for shape-controlled nanostructures synthesis. New applications demand clear understanding of the processes that occur during track membranes formation. For high-precision control of the end-product parameters, it is necessary to establish the correlation between etching conditions and track membranes characteristics (pores dimensions, porosity and membranes thicknesses). For this purpose, in the paper it is considered the technique of membranes formation with 10 nm - 10 μm cylindrical pores and correlation between their parameters and processing modes is studied. © 2019 Elsevier Ltd