Investigation of the structural changes and catalytic properties of feni nanostructures as a result of exposure to gamma radiation

The paper presents the results of changes in the structural characteristics, and the degree of texturing of FeNi nanostructures close in composition to permalloy compounds as a result of directed modification by gamma radiation with an energy of 1.35 MeV and doses from 100 to 500 kGy. The choices of energy and radiation doses were due to the need to modify the structural properties, which consisted of annealing the point defects that occurred during the synthesis along the entire length of the nanotubes. The initial FeNi nanostructures were polycrystalline nanotubes of anisotropic crystallite orientation, obtained by electrochemical deposition. The study found that exposure to gamma rays led to fewer defects in the structure, and reorientation of crystallites, and at doses above 300 kGy, the presence of one selected texture direction (111) in the structure. During tests of the corrosion resistance of synthesized and modified nanostructures in a PBS solution at various temperatures, it was found that exposure to gamma rays led to a significant decrease in the rate of degradation of nanotubes and an increase in the potential life of up to 20 days. It was established that at the first stage of testing, the degradation of nanostructures is accompanied by the formation of oxide inclusions, which subsequently lead to the formation of pitting corrosion and subsequent partial or complete destruction of the nanostructures. It is shown that gamma radiation is promising not only for targeted modification of nanostructures and increasing resistance to degradation, but also for increasing the rate of catalytic reactions of the PNA-PPD type. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Republic of KazakhstanFunding: This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant AP05133578)

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)

The study of the applicability of electron irradiation for FeNi microtubes modification

The paper presents the results of a study of irradiation of high-energy electrons by an array of FeNi nanostructures with doses from 50 to 500 kGy. Polycrystalline nanotubes based on FeNi, the phase composition of which is a mixture of two face-centered phases, FeNi3 and FeNi, were chosen as initial samples. During the study, the dependences of the phase transformations, as well as changes in the structural parameters as a result of electronic annealing of defects, were established. Using the method of X-ray diffraction, three stages of phase transformations were established: FeNi3 ≌ FeNi→FeNi3 ≪ FeNi→FeNi. After increasing the radiation dose above 400 kGy, no further phase changes were followed, indicating the saturation of defect annealing and completion of the lattice formation process. It was found that an increase in the degree of crystallinity and density of the microstructures as a result of irradiation indicates electronic annealing of defects and a change in the phase composition. It was established that the initial microtubes, in which two phases are present, leads to the appearance of differently oriented crystallites of different sizes in the structure, which contributes to a large number of grain boundaries and also a decrease in density, and are subject to the greatest degradation of structural properties. For modified samples, the degradation rate decreases by 5 times. In the course of the study, the prospects of the use of electron irradiation with doses above 250 kGy for directed modification of FeNi microtubes and changes in structural features were established. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Republic of Kazakhstan: AP05133578Funding: This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant AP05133578)

Formation of Stable Lithium-Containing Ceramics Using Solid-Phase Synthesis Method

Today, one of the most promising materials for a wide range of practical applications is lithium-containing ceramics based on Li2TiO3 . At the same time, despite the high potential of their practical application, a number of questions remains related to the methods of their preparation, as well as the formation of a stable crystal structure and a pure-phase composition. To solve these issues, this paper proposes a method for obtaining stable Li2TiO3 ceramics, which is based on solid-phase synthesis combined with the high-temperature sintering of ceramics. During the studies carried out using X-ray diffraction methods, temperature dependences of phase transformations of the TiO2/Li2Ti6O13 → Li2TiO3 type were determined, according to which, at temperatures above 800◦C, the formation of a stable Li2TiO3 phase characterized by a high structural ordering degree of 89–91% is observed. The dependence of changes in structural, optical and ferroelectric characteristics on the conditions of synthesis and phase composition of ceramics was also determined. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. AP08855734)

Effect of Irradiation with Low-Energy He2+ Ions on Degradation of Structural, Strength and Heat-Conducting Properties of BeO Ceramics

The paper is devoted to the study of radiation-induced damage kinetics in beryllium oxide ceramics under irradiation with low-energy helium ions with fluences of 1015–1018 ion/cm2 . It was revealed that at irradiation fluences above 1017 ion/cm2, a decrease in radiation-induced damage formation and accumulation rate is observed, which indicates the saturation effect. At the same time, the main mechanisms of structural changes caused by irradiation at these fluences are amorphization processes and dislocation density increase, while at fluences of 1015–1016 ion/cm2, the main mechanisms of structural changes are due to the reorientation of crystallites and a change in texture, with a small contribution of crystal lattice distorting factors. It was discovered that the radiation-induced damage accumulation as well as an implanted helium concentration increase leads to the surface layer destruction, which is expressed in the ceramic surface hardness and wear resistance deterioration. It was determined that with irradiation fluences of 1015–1016 ion/cm2, the decrease in thermal conductivity is minimal and is within the measurement error, while an increase in the irradiation fluence above 1017 ion/cm2 leads to an increase in heat losses by more than 10%. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. AP08855828)

Study of the influence of the phase composition and crystal structure of FexNi100−xnanostructures on the efficiency of using lithium-ion batteries as anode materials

The results of the efficiency of using FexNi100−xnanotubes as anode materials for lithium-ion batteries have been obtained. In the course of research, it was found that an increase in the concentration of nickel in the structure to 40 and 60 at.% leads to a sharp increase in the resource number of cycles by more than two times in comparison with iron nanotubes. Such a difference in the resource lifetime is due to the higher stability of FexNi100−xnanotubes with a nickel concentration of more than 40 at.% to destruction, as well as resistance to oxidation. © 2020. All Rights Reserved.This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant AP05133578)

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)

Study of Change in Beryllium Oxide Strength Properties as a Result of Irradiation with Heavy Ions

The paper presents data on changes in strength properties, including data on microhardness, crack resistance, bending strength and wear of BeO ceramics as a result of irradiation with heavy accelerated ions. The following types of ions were selected as heavy ions: O2+ (28 MeV), Ar8+ (70 MeV), Kr15+ (147 MeV), Xe22+ (230 MeV). Radiation doses were 10 13 -10 15 ion/cm2, which make it possible to assess the effect of both single defects arising from radiation, and cluster overlapping defective areas occurring at large radiation doses. During the studies carried out, it was found that an increase in the ion energy and, consequently, in the damaging ability and depth of the damaged area, leads to a sharp decrease in the strength mechanical characteristics of ceramics, which is due to an increase in defective areas in the material of the near-surface damaged layer. However, an increase in irradiation dose for all types of exposure results in an almost equilibrium decrease in strength characteristics and the same trend of change in strength characteristics. The obtained dependencies indicate that the proposed mechanisms responsible for changing the strength properties can, under certain assumptions, be extrapolated to various types of exposure to heavy ions in the energy range (25-250 MeV). © 2021. All Rights Reserved.This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. AP08855828)

Study of the Application Efficiency of Irradiation with Heavy Ions to Increase the Helium Swelling Resistance of BeO Ceramics

This paper considers the possibilities of increasing radiation resistance to helium swelling of beryllium oxide ceramics due to preliminary irradiation with heavy ions. Interest in this topic is due to the possibility of using these ceramics as materials for inert matrices of nuclear fuel and structural materials reflectors of high-temperature reactors. The samples studied were irradiated in two stages, namely irradiation with heavy Ar8+, Kr15+, and Xe22+ ions with a fluence of 1012 ion/cm2 and subsequent irradiation with He2+ ions with a fluence of 5x1017 ion/cm2 . The main parameters used to compare and determine radiation modification efficiency were the crystal-structure swelling degree, a decrease in the hardness, and wear resistance of ceramics after irradiation with He2+ ions. During the studies carried out, it was found that preliminary irradiation with heavy Ar8+, Kr15+, and Xe22+ ions leads to a significant increase in radiation swelling resistance, as well as to an increase in crack resistance and wear resistance. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. AP08855828)

Electron beam induced enhancement of the catalytic properties of ion-track membranes supported copper nanotubes in the reaction of the P-nitrophenol reduction

This study considers the effect of various doses of electron irradiation on the crystal structure and properties of composite catalysts based on polyethylene terephthalate track-etched membranes and copper nanotubes. Copper nanotubes were obtained by electroless template synthesis and irradiated with electrons with 3.8 MeV energy in the dose range of 100–250 kGy in increments of 50 kGy. The original and irradiated samples of composites were investigated by X-ray diffraction technique (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The improved catalytic activity of composite membranes with copper nanotubes was demonstrated by the example of the reduction reaction of p-nitrophenol in the presence of sodium borohydride. Irradiation with electrons at doses of 100 and 150 kGy led to reaction rate constant increases by 35 and 59%, respectively, compared to the non-irradiated sample. This enhancing catalytic activity could be attributed to the changing of the crystallite size of copper, as well as the surface roughness of the composite membrane. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Republic of Kazakhstan: AP05130797Funding: A.A.M. gratefully acknowledges the funding of the Ministry of Education and Science of the Republic of Kazakhstan (Project AP05130797)