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The electrical conductivity and volt–ampere characteristics (VAC) of the p-CuTlS2 single crystal with specific resistance ρ = 4 0 Ω ⋅ cm and irradiated by γ -quantum were studied in the range of 100–300 K temperature and 10–104 V/cm. It was determined that the cause of the conduction disorder observed in the CuTlS2 single crystal at low electric fields and high radiation doses is the formation of defect clusters dominated by cation vacancies. A sharp increase in current at high electric fields and temperatures occurs as a result of thermo-field ionization of the acceptor level with activation energy Δ E a = 0. 0 8 eV and the ionization voltage decreases with increasing radiation dose. Based on the determination of the parameters (λ , r m , n 0 , ε) that determine the mechanism of current flow, the dependence of the shape of the potential hole on the radiation dose was determined. [ABSTRACT FROM AUTHOR]

RE-doped β-Ga2O3 seems attractive for future high-power LEDs operating in high irradiation environments. In this work, we pay special attention to the issue of radiation-induced defect anisotropy in β-Ga2O3, which is crucial for device manufacturing. Using the RBS/c technique, we have carefully studied the structural changes caused by implantation and post-implantation annealing in two of the most commonly used crystallographic orientations of β-Ga2O3, namely the (-201) and (010). The analysis was supported by advanced computer simulations using the McChasy code. Our studies reveal a strong dependence of the structural damage induced by Yb-ion implantation on the crystal orientation, with a significantly higher level of extended defects observed in the (-201) direction than for the (010). In contrast, the concentration and behavior of simple defects seem similar for both oriented crystals, although their evolution suggests the co-existence of two different types of defects in the implanted zone with their different sensitivity to both, radiation and annealing. It has also been found that Yb ions mostly occupy the interstitial positions in β-Ga2O3 crystals that remain unchanged after annealing. The location is independent of the crystal orientations. We believe that these studies noticeably extend the knowledge of the radiation-induced defect structure, because they dispel doubts about the differences in the damage level depending on crystal orientation, and are important for further practical applications. [ABSTRACT FROM AUTHOR]

RE-doped β-Ga2O3 seems attractive for future high-power LEDs operating in high irradiation environments. In this work, we pay special attention to the issue of radiation-induced defect anisotropy in β-Ga2O3, which is crucial for device manufacturing. Using the RBS/c technique, we have carefully studied the structural changes caused by implantation and post-implantation annealing in two of the most commonly used crystallographic orientations of β-Ga2O3, namely the (-201) and (010). The analysis was supported by advanced computer simulations using the McChasy code. Our studies reveal a strong dependence of the structural damage induced by Yb-ion implantation on the crystal orientation, with a significantly higher level of extended defects observed in the (-201) direction than for the (010). In contrast, the concentration and behavior of simple defects seem similar for both oriented crystals, although their evolution suggests the co-existence of two different types of defects in the implanted zone with their different sensitivity to both, radiation and annealing. It has also been found that Yb ions mostly occupy the interstitial positions in β-Ga2O3 crystals that remain unchanged after annealing. The location is independent of the crystal orientations. We believe that these studies noticeably extend the knowledge of the radiation-induced defect structure, because they dispel doubts about the differences in the damage level depending on crystal orientation, and are important for further practical applications. [ABSTRACT FROM AUTHOR]

Abstract RE-doped β-Ga2O3 seems attractive for future high-power LEDs operating in high irradiation environments. In this work, we pay special attention to the issue of radiation-induced defect anisotropy in β-Ga2O3, which is crucial for device manufacturing. Using the RBS/c technique, we have carefully studied the structural changes caused by implantation and post-implantation annealing in two of the most commonly used crystallographic orientations of β-Ga2O3, namely the (-201) and (010). The analysis was supported by advanced computer simulations using the McChasy code. Our studies reveal a strong dependence of the structural damage induced by Yb-ion implantation on the crystal orientation, with a significantly higher level of extended defects observed in the (-201) direction than for the (010). In contrast, the concentration and behavior of simple defects seem similar for both oriented crystals, although their evolution suggests the co-existence of two different types of defects in the implanted zone with their different sensitivity to both, radiation and annealing. It has also been found that Yb ions mostly occupy the interstitial positions in β-Ga2O3 crystals that remain unchanged after annealing. The location is independent of the crystal orientations. We believe that these studies noticeably extend the knowledge of the radiation-induced defect structure, because they dispel doubts about the differences in the damage level depending on crystal orientation, and are important for further practical applications.

Kinetics of degradation of the nonequilibrium charge carrier lifetime (τ) in Czochralski‐grown (Cz) n‐Si irradiated with 1 MeV electrons at different temperatures in the range from 20 to 285 °C are experimentally and theoretically investigated. It is established that changes in τ are qualitatively and quantitatively determined by the temperature of electron irradiation. Analysis of experimental data using the Shockley‐Read‐Hall (SRH) theory shows that the formation of recombinationally active divacancy‐oxygen (V2O) and vacancy‐oxygen (VO) complexes is the main mechanism of τ degradation in this experiment. [ABSTRACT FROM AUTHOR]

BaF2 and CaF2 crystals possessing high radiation resistance and as high-time resolution scintillators are used in high energy physics. In the present work, radiation defects in BaF2 and CaF2 crystals are investigated upon irradiation with 220 and 230 MeV 132Xe ions to fluences of 1011 -1014 ions/ cm2 . Optical absorption spectra were measured in the range from 10 to 1.5 eV. To study thermal annealing of the coloration centers created in BaF2 and CaF2 single crystals, step-by-step annealing of radiation defects was carried out. Multiple heating-cooling-measurement cycles were performed under identical conditions with increasing annealing temperature (Tann) by 20-30 K. All spectra were measured at RT. It is assumed that the radiation-induced absorption band at 9.7 eV in CaF2 is made up of a combined contribution of anion clusters created in the ion track region and complex hole aggregates. The center responsible for the 8.15 eV band also has a hole nature and a structure close to the 6.5 eV center. In the UV region of the BaF2 spectrum, a slight increase of the 9.18 eV band is observed in the temperature range 450-575K, which is accompanied by a decrease of the bands with maxima of 6.5 and 8.2 eV, i.e., the latter is also of hole nature. The bands 7.4 eV, 2.24 eV and 3.04 eV practically do not change in the whole annealing temperature range. By analogy with CaF2, in Xe-irradiated BaF2 single crystals, the highenergy bands below the fundamental absorption can also be of anion cluster nature. [ABSTRACT FROM AUTHOR]

Tungsten (W) samples containing 0, 1, 3, and 5 at.% rhenium (Re) were irradiated by 20 MeV W ions to 0.5 dpa at 290 K and to 0.3 dpa at 1350 K. An additional set of samples was irradiated to 0.5 dpa at 290 K and then annealed at 1350 K. The irradiated samples were exposed to a deuterium (D) plasma at 370 K. D concentration profiles in the samples were measured using D(He3,p)α nuclear reaction analysis. The D binding states in the defects were analysed using thermal desorption spectroscopy (TDS). In the case of irradiation at 290 K, the trapped D concentration monotonically increases with increasing Re concentration: in W-5%Re it is 17% higher than in pure W. On the contrary, for irradiation at 1350 K the trapped D concentration monotonically decreases with increasing Re concentration: in W-5%Re it is 50 times smaller than in pure W. In the case of annealing at 1350 K of the samples irradiated at 290 K, the Re presence yields only up to three times reduction of trapped D concentration compared with pure W. TDS shows that the nature of D trapping sites is different for the irradiations at 290 K and 1350 K. We attribute the reduced D trapping in W-Re alloys irradiated at 1350 K to the reduction of cavity growth caused by the presence of Re.

The study investigates alterations in the mechanical and thermophysical properties of ceramics composed of xLi2ZrO3–(1−x)Li4SiO4 as radiation damage accumulates, mainly linked to helium agglomeration in the surface layer. This research is motivated by the potential to develop lithium-containing ceramics characterized by exceptional strength properties and a resistance to the accumulation of radiation damage and ensuing deformation distortions in the near-surface layer. The study of the radiation damage accumulation processes in the near-surface layer was conducted through intense irradiation of ceramics using He2+ ions at a temperature of 700 °C, simulating conditions closely resembling operation conditions. Following this, a correlation between the accumulation of structural modifications (value of atomic displacements) and variations in strength and thermophysical characteristics was established. During the research, it was observed that two-component ceramics exhibit significantly greater resistance to external influences and damage accumulation related to radiation exposure compared to their single-component counterparts. Furthermore, the composition that provides the highest resistance to softening in two-component ceramics is an equal ratio of the components of 0.5Li2ZrO3–0.5Li4SiO4 ceramics.

The study investigates alterations in the mechanical and thermophysical properties of ceramics composed of xLi2ZrO3–(1−x)Li4SiO4 as radiation damage accumulates, mainly linked to helium agglomeration in the surface layer. This research is motivated by the potential to develop lithium-containing ceramics characterized by exceptional strength properties and a resistance to the accumulation of radiation damage and ensuing deformation distortions in the near-surface layer. The study of the radiation damage accumulation processes in the near-surface layer was conducted through intense irradiation of ceramics using He2+ ions at a temperature of 700 °C, simulating conditions closely resembling operation conditions. Following this, a correlation between the accumulation of structural modifications (value of atomic displacements) and variations in strength and thermophysical characteristics was established. During the research, it was observed that two-component ceramics exhibit significantly greater resistance to external influences and damage accumulation related to radiation exposure compared to their single-component counterparts. Furthermore, the composition that provides the highest resistance to softening in two-component ceramics is an equal ratio of the components of 0.5Li2ZrO3–0.5Li4SiO4 ceramics. [ABSTRACT FROM AUTHOR]

The work presents the study results of the determination of the resistance of neodymium zirconate doped with MgO and Y2O5 to radiation damage stemming from irradiation with heavy ions akin to nuclear fuel fission fragments. The attraction towards this type of ceramics stems from its potential to raise the operational temperatures within the core of next-generation nuclear reactors. This is owed to its superior thermal conductivity when compared to zirconium dioxide, coupled with the heightened strength parameters that signify the ceramics' resistance against external factors. The main results of this study are to determine the influence of the formation of substitution or interstitial phases when adding magnesium and yttrium oxides to the composition, on increasing the stability of the strength and thermophysical parameters of neodymium zirconate to the radiation defects accumulation in the damaged surface layer. During the studies, it was found that the formation of impurity phases in the form of MgO inclusions (when it is added to the composition) and a substitution phase of the Y2Zr2O7 type (with the addition of Y2O5) results in an elevation in the hardness and crack resistance stability of neodymium zirconate ceramics, which indicates the positive effect of doping linked to the formation of additional interphase boundaries that prevent strain embrittlement of the damaged layer under high-dose irradiation. During determination of the thermophysical parameters of the studied neodymium zirconate ceramics, it was observed that the formation of interphase boundaries during doping not only enhances thermal conductivity but also mitigates the decline in the thermal conductivity coefficient during irradiation for two-phase ceramics in comparison with undoped neodymium zirconate ceramics. [ABSTRACT FROM AUTHOR]

A molecular dynamics study was carried out on the radiation damage and the onset of plastic deformation in the single-crystal Fe–10Ni–20Cr alloy exposed to different radiation doses under uniaxial tension. It has been shown that upon reaching a threshold radiation dose of ~0.020–0.025 dpa, the number of radiation-induced defects levels off. This behavior of the material is explained by the establishment of equilibrium between the generation and annihilation of radiation defects at radiation doses exceeding the threshold value. The major part of interstitial atoms and vacancies form large-sized clusters and dislocation loops. The formed clusters are characterized by decreased and increased Ni and Cr concentrations, respectively. Stacking faults, as the main carriers of plasticity in such samples, always originate near the largest radiation defects. [ABSTRACT FROM AUTHOR]

The results of modification of WC–Co samples by a pulsed beam of nitrogen ions (200–300 keV, 120 ns) with an energy density of 7–8 J/cm2 are presented. It is shown that the change in the structure occurs in the near-surface layer with a thickness of 20–30 μm, which significantly exceeds the range of ions in the target (≈0.5 μm) and the depth of propagation of the thermal front during the pulse (≈1 μm). Various mechanisms of the long-range effect, namely, the formation of a shock wave, the generation of primary radiation defects, etc. are analyzed. It is shown that the long-range effect is associated with the charge exchange of ions and the formation of fast atoms. The simulation of the charge exchange of ions in the gaseous layer of desorbed molecules is performed. It is found that the probability of ion charge exchange in the processes N+ + N2 → N0 and N+ + O2 → N0 significantly exceeds 100%, which indicates that the effect of irradiation of the target by fast atoms must be taken into account. In contrast to ions, when the target is irradiated with atoms, the efficiency of the formation of radiation defects is much higher. [ABSTRACT FROM AUTHOR]

The results of studies on the wear resistance of machine parts made of aluminum alloys with insulated layers obtained by activating surface layers (SLs) are considered. It is shown that, in relation to aluminum alloys, traditional ion nitriding technologies are ineffective due to the low rate of nitrogen diffusion and the heterogeneous structure of the nitrided layer (NL). The results of a fourfold increase in the intensity of diffusion processes of ion nitriding during activation of the surface layer of an aluminum alloy by methods of surface plastic deformation and high-energy ion implantation compared with traditional ion nitriding are presented. It is shown that when preparing the surface of an aluminum alloy by the method of high-energy ion implantation, the wear resistance of the nitrided layer is provided, exceeding by more than three times the wear resistance of the nitrided layer obtained during surface preparation by the method of surface plastic deformation. A new ion nitriding technology has been proposed, which makes it possible to increase the productivity of the nitriding process and the wear resistance of the AC by eliminating the oxide film by ion etching in vacuum. It is shown that the use of the method of high-energy ion implantation at an ion energy of about 25 keV ensures, due to the occurrence of a long-range effect, the formation of aluminum alloy parts in the surface layer at a depth commensurate with the thickness of the nitrided layer of radiation defects of the crystal structure, which significantly intensify nitrogen diffusion, as well as block grain boundaries inhibiting diffusion processes in them. [ABSTRACT FROM AUTHOR]

The results of studies of the changes in the electrophysical parameters of PIN photodiodes made on monocrystalline silicon wafers of the p-type of conductivity of orientation (100) with ρ = 1000 Ohm cm, when irradiated with γ-quanta from a 60Co source, are presented. It is established that as a result of the irradiation of the PIN photodiodes doses up to 2 × 1015 quanta/cm2 results in an increase in the reverse dark current by more than an order of magnitude. However, the shape of the curve of the dependence of the current on the applied reverse voltage of irradiated PIN photodiodes does not change qualitatively, just as for the original devices, there are three regions with different dependencies of the current on voltage—sublinear, superlinear, and linear—caused by different mechanisms of the generation-recombination processes in the depletion region of the p–n transition. The main reason for the increase in the reverse current of PIN photodiodes as a result of the irradiation of γ-quanta is the formation of the generation-recombination centers of radiation origin due to the condensation of the primary radiation defects (vacancies and/or self-interstitial atoms) on the technological residual structural defects formed both during the growth of silicon single crystals and during subsequent high-temperature treatments during the formation of devices. [ABSTRACT FROM AUTHOR]

In In this study, the optical properties of magnesium-aluminate spinel were examined after being irradiated with 220 MeV Xe ions. The research aimed to simulate the impact of nuclear fuel fission fragments on the material. The following measurements were taken during the experiments: transmission spectra in the IR region (190–7000) nm, optical absorption spectra in the range (1.2–6.5) eV, and Raman spectra were measured along the depth of ion penetration from the surface to 30 µm. A peak with a broad shape at approximately 5.3 eV can be observed in the optical absorption spectrum of irradiated spinel crystals. This band is linked to the electronic color centers of F+ and F. Meanwhile, the band with a maximum at ~(3–4) eV is attributed to hole color centers. Apart from the typical Raman modes of an unirradiated crystal, additional modes, A1g* (720 cm−1), and Eg* (385 cm−1), manifested mainly as an asymmetric shoulder of the main Eg mode, are also observed. In addition, the Raman spectroscopy method showed that the greatest disordering of crystallinity occurs in the near-surface layer up to 4 μm thick. At the same time, Raman scattering spectroscopy is sensitive to structural changes almost up to the simulated value of the modified layer, which is an excellent express method for certifying the structural properties of crystals modified by swift heavy ions. [ABSTRACT FROM AUTHOR]

Tensoelectric properties of the uniaxially deformed along the crystallographic direction [100] n-Ge single crystals, irradiated by the flows of electrons 5 ⋅ 10 15 el. / cm 2 , 1 ⋅ 10 16 el. / cm 2 , 2 ⋅ 10 16 el. / cm 2 and 5 ⋅ 10 16 el. / cm 2 , with the energy of 10 MeV , were investigated. Mechanisms of changes in resistivity and mobility of current carriers under the uniaxial deformation for the studied n-Ge single crystals based on the measurements of tenso-Hall effect and infrared Fourier spectroscopy were established.The presence of tensoresistance for n-Ge single crystals, irradiated by the flow of the electrons Ω ≤ 1 ⋅ 10 16 el. / cm 2 , is associated with changes under the uniaxial pressure of electron concentration in the conduction band and holes in the valence band due to a decrease of the ionization energy of the deep level E V + 0.27 eV of the radiation defects which belongs to the complexes V O i I 2 G e , at the uniaxial deformation. A significant increase of the effective mobility of carriers current in uniaxially deformed single crystals n-Ge is primarily related to the deforming redistribution of electrons between the branch of 'light' holes and the level E V + 0.27 eV . For single crystals n-Ge irradiated by the flows of electrons Ω ≥ 2 ⋅ 10 16 el. / cm 2 , which lead to the n-p conversion of the conductivity type of germanium, significant tensoresistance is observed only at the pressures P ≤ 0.5 GPa . In this case, the resistivity of n-Ge decreases both due to an increase in the concentration of holes and their mobility under the deformation. Mobility of holes does not depend on deformation for uniaxial pressures P > 0.5 GPa , and a slight decrease in the resistivity of the researched single crystals n-Ge is caused by an increase in their concentration. Radiation-induced tensosensitivity at the room temperature for single crystals n-Ge can be used in technologies for creating uniaxial pressure sensors based on germanium. Obtained radiation effect of a significant increase in the mobility of current carriers for the uniaxially deformed n-Ge single crystals can find its practical application in the creation of 'germanium' channels of n-MOSFET and p-MOSFET transistors. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this work, the effect of irradiation with heavy Kr15+ and Xe22+ ions on the change in the structural and strength properties of CeO2 microstructural ceramics, which is one of the candidates for inert matrix materials for dispersed nuclear fuel, is considered. Irradiation with heavy Kr15+ and Xe22+ ions was chosen to determine the possibility of simulation of radiation damage comparable to the action of fission fragments, as well as neutron radiation, considering damage accumulation at a given depth of the near-surface layer. During the research, it was found that the main changes in the structural properties with an increase in the irradiation fluence are associated with the crystal lattice deformation distortions and the consequent radiation damage accumulation in the surface layer, and its swelling. Evaluation of the effect of gaseous swelling caused by the radiation damage accumulation showed that a variation in the ion type during irradiation results in a growth in the value of swelling and destruction of the near-surface layer with the accumulation of deformation distortions. Results of the strength variation demonstrated that the most intense decrease in the near-surface layer hardness is observed when the fluence reaches more than 1013–1014 ion/cm2, which is typical for the effect of overlapping radiation damage in the material. [ABSTRACT FROM AUTHOR]

The extraordinary radiation resistance of single crystals and ceramics of magnesium-aluminum spinel to neutron irradiation is known, but the mechanisms that provide it are not yet understood. Irradiation of crystals with fast electrons creates defects partially similar to defects in neutron irradiation. The difference in the destructive effect is the significant level of ionization during electron irradiation. Therefore, to compare the results of irradiation by different sources, it is necessary to determine the parameters of radiation defects. One of them is the conditions of radiation damage recovery. When irradiating the crystals with electrons with an energy of 12.5 MeV to a fluence of 6.8∙1016 eV/cm2, the concentration of defects such as F-centers 2.6∙1016 cm-3 and V-centers 3∙1017 cm-3 was obtained. TSL and optical absorption spectroscopy methods were used to determine the state of radiation defects in crystals during annealing. Since annealing at temperatures above 900 K leads to complete discoloration of all optically active centers, therefore, to determine the effect of annealing at higher temperatures, the crystals after annealing were irradiated with ultraviolet light. At temperatures above 900 K, cationic disorder begins to increase, but annealing at 1010 K for 30 minutes was not enough to completely restore the damage to the crystal lattice created by electron irradiation. This is expected, given the characteristic relaxation time of cation disorder, which reaches 1000 hours at this temperature. However, increasing the annealing temperature to 1050 K, in addition to the recovery of radiation defects, creates a noticeable additional difference in TSL, probably due to the formation of complexes from residual F-centers. However, determining the difference between irradiated and non-irradiated crystals gives a difference in the concentration of F-centers at the level of 1015 cm-3.

The effect of ion energy in a focused ion beam in the range 12–30 keV on the formation depth of nonradiative recombination centers during etching of the Al0.18Ga0.82As/GaAs/Al0.18Ga0.82As double heterostructure has been studied. It is shown that an increase in the ion energy leads to an increase in the concentration and propagation depth of radiation defects. It was found that during etching of focused ion beam with ion energies above 15 keV, the depth of formation of radiation defects exceeds 900 nm, which does not correspond to the calculations in the Stopping and Range of Ions in Matter. [ABSTRACT FROM AUTHOR]

To justify the safety of dry storage, thermal tests of VVER-1000 fuel rods in electrically heated modules in a helium medium were carried out, realizing stationary conditions and a thermal cycling regime with different cycle times and a total test time of 427–468 days. The effect of thermal tests on the elongation of fuel rods that were used in VVER-1000 reactors for one year (fuel burnup of ~20 MW day/kg U) and for six years (burnup of ~70 MW day/kg U) was studied. Fuel rods with high fuel burnup elongated less than those with low burnup. The maximum values of elongation were registered for fuel rods with low burnup: 6.0 mm when tested under stationary conditions and 9.5 mm in the thermal cycling mode. Hoop strain of the fuel rods increased insignificantly. The presence of gas pressure under the cladding provides tensile stresses, creating conditions for the implementation of thermal creep. For fuel rods with lower fuel burnup, the gap between the fuel and the cladding was preserved along the entire height of the core (column). The main mechanism for elongation of fuel rods is the cladding thermal creep under the action of increased effective axial stresses arising from the internal fuel rod gas and the pressure of the fuel column on the spring plunger. Thermal cycling leads to a greater elongation of the fuel rods owing to a higher cladding creep rate at the unsteady-state stage in short cycles. [ABSTRACT FROM AUTHOR]

The temperature dependences of diffusion characteristics of the irradiation-induced defects, namely, clusters of self-interstitial atoms (SIAs) containing up to five atoms, in bcc V (vanadium) have been studied by the method of molecular dynamics in the temperature range of 300–1000 K. The diffusion characteristics include the coefficient of diffusion, the tracer correlation factor, the average displacement before changing the direction of migration, and the frequency of changing the direction of migration. The values of the activation energy of diffusion and the activation energy of changing the direction of migration for the considered types of defects in different temperature ranges have been determined. The dependences of the mechanism of (1D vs 3D) diffusion of SIA clusters on the temperature and cluster size and their possible influence on the parameters of phenomenological models of changes in the microstructure of a material under irradiation (sink strengths of spherical absorbers) are discussed. [ABSTRACT FROM AUTHOR]

The effect of proton irradiation on the structure, phase composition, defect state and nanohardness of Zr/Nb nanoscale multilayer coatings was investigated. Preservation of the Zr/Nb layered structure with 50 and 100 nm thick layers, was observed after irradiation with protons at 1720 keV energy and 3.4 × 1015, 8.6 × 1015 and 3.4 × 1016 ions/cm2 fluences, and the interfaces remained incoherent. In the Zr/Nb nanoscale multilayer coatings with individual layer thicknesses of 10 and 25 nm, there were insignificant fluctuations in interplanar distance, which were influenced by changes in irradiation fluence, and the interfaces were partially destroyed and became semicoherent. Changing irradiation fluence in the investigated ranges led to a decrease in the nanohardness of the Zr/Nb nanoscale multilayer coatings with individual layer thicknesses of 10–50 nm. Variable-energy positron Doppler broadening analysis revealed that these changes are primarily caused by peculiarities of the localization and accumulation of the embedded ions and do not cause a significant increase in the S-parameters of Zr/Nb nanoscale multilayer coatings with a layer thickness less than 100 nm. [ABSTRACT FROM AUTHOR]

Composite oxide ceramics CeZrO4–YZrO3 obtained by mechanochemical synthesis were chosen as objects of study. The most dangerous type of radiation defect in structural materials is associated with helium accumulation in the structure of the near-surface layer. This can lead to the destruction and swelling of the material, resulting in a decrease in its strength and thermal characteristics. During the studies, it was found that the most significant structural changes (deformation of the crystal lattice, the magnitude of microdistortions of the crystal lattice) are observed with irradiation fluence above 5×1016 ion/cm2, while the nature of the changes is exponential. X-ray diffraction analysis found that the nature of the crystal structure deformation has a pronounced type of stretching due to the accumulation of implanted helium and its subsequent agglomeration. A comparative analysis with data on microdistortions of the crystal lattice and the values of microhardness and softening of ZrO2 and CeO2 showed that two-phase ceramics of the cubic type CeZrO4-YZrO3 are more resistant to radiation-induced degradation than single-phase ZrO2 and CeO2. Results of strength and thermophysical characteristics showed that the presence of two phases increases resistance to destruction and disorder, leading to a decrease in strength and thermal conductivity. [ABSTRACT FROM AUTHOR]

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The effect of helium ion irradiation on the microstructure and properties of composites based on Zr/Nb nanoscale multilayer coatings (NMCs) was studied. X-ray diffraction (XRD), transmission electron microscopy (TEM), and variable-energy Doppler broadening spectroscopy (DBS) were used for the in-depth analysis of defects in the irradiated NMCs. After irradiation of the Zr/Nb NMCs with helium ions at a 1017 ion/cm2 dose, the layered structure was generally retained, but the internal stresses in the layers were increased, which caused wave-like distortion in the ion deposition zone. The Zr/Nb NMCs with an individual layer thickness of 25 nm were characterized by the smallest microstress changes, but single blisters were formed in the near-surface region. The microstructure of the Zr/Nb NMCs with a layer thickness of 100 nm exhibited relatively smaller changes upon helium ion irradiation. The prevailing positron-trapping center was the reduced-electron-density area at the interfaces before and after irradiation of the Zr/Nb NMCs regardless of the layer thickness. However, the layer thickness affected the DBS parameter profiles depending on the positron energy, which was probably due to the different localization of implanted ions within the layers or at the interfaces. [ABSTRACT FROM AUTHOR]

This article discusses the experimental results of wear resistance of machine parts made of alloyed steels, with nitrided layers, with structures formed with and without nitride mesh. It has been demonstrated that the nitrided layers with traditional structure under certain conditions of friction and wear do not completely exhibit their potentials of wear resistance as a consequence of disintegration of their fragments due to weakened intergranular boundaries in nitrided layer resulting from their oversaturation with nitrogen. The models of formation of structures of nitrided layers are schematically illustrated including their behavior during friction and wear. It has been mentioned that the use of high energy ion implantation at an ion energy of about 18–26 keV due to the occurrence of the long-range effect provides formation of radiation defects of a crystalline structure at a depth comparable with the thickness of a nitrided layer allowing it to significantly intensify nitrogen diffusion as well as to block grain boundaries, which inhibit diffusion processes in them. It has been determined that while intensive plastic deformation of the surface layer improves diffusion intensity, still, it can be efficiently applied only in combination with high energy ion implantation. The results of comparative wear tests are exemplified by screw pump rotors operating under conditions of intensive friction wear. It has been demonstrated that the absence of nitride mesh in a nitrided layer improves wear resistance of the nitrided layer by about 3–4 times. [ABSTRACT FROM AUTHOR]

Laplace photoinduced transient spectroscopy has been applied to determine the electronic properties and concentrations of deep traps in high purity n-type silicon irradiated with high fluences of 23-MeV protons. From the temperature dependence of thermal emission rates of excess charge carriers obtained by the analysis of the photocurrent relaxation waveforms measured at temperatures of 30–320 K, eight deep traps with activation energies ranging from 255 to 559 meV have been resolved. The dependence of these trap's concentrations on the proton fluence are demonstrated for the fluence values ranging from 1 × 1014 to 5 × 1015 neq/cm2. In comparison to the previously reported results of theoretical and experimental studies on the electronic properties of small vacancy clusters in irradiated silicon, we tentatively attribute four detected traps with activation energies of 255, 367, 405, and 512 meV to the energy levels related to the 2−/− charge state changes of divacancy (V2), trivacancy (V3), tetravacancy (V4), and pentavacancy (V5), respectively. Simultaneously, we propose the attribution of four deep traps with higher activation energies of 415, 456, 526, and 559 meV to the energy levels related to the −/0 charge state changes of these small vacancy clusters, respectively. [ABSTRACT FROM AUTHOR]

The paper presents the results of changes in the strength characteristics of thin film coatings based on compounds of copper-bismuth, copper-magnesium, copper-nickel. The dependences of the influence of the phase composition on the strength characteristics, such as the coefficient of friction, bending strength and impact coefficient, are established. The effect of irradiation with helium ions with a high radiation dose of 1015-1017 ion/cm2 on the strength characteristics is evaluated. It is shown that an increase in the radiation dose leads to a decrease in strength properties due to the appearance of a large concentration of defects in the structure.

The paper presents the results of a study of the effect of proton and ion radiation on structural changes in nitride ceramics, which have a high potential for using as a structural material for GenIV nuclear reactors. Proton beams with an energy of 1.5 MeV and low-energy helium (He2+) and carbon (C2+) ions with an energy of 40 keV were used, to simulate defect formation and to estimate ceramics radiation resistance. According to the data obtained, it has been established that AlN nitride ceramics have high radiation resistance to the effects of proton radiation. While under irradiation with C2+ ions, the observed degradation of the surface layer is due to the accumulation of carbon in the structure with the subsequent formation of impurity carbide inclusions. It is established that the accumulation of slightly soluble ions of helium and carbon in the structure of the surface layer leads to an increase in the strain and distortion of crystal lattice due to introducing ions into the interstitial lattice and breaking chemical and crystalline bonds.

In this study the results of structural and morphological changes in Ni12+ heavy ion irradiated BeO ceramics are presented. Irradiation was carried out on DC-60 heavy ion accelerator using Ni12+ ions with an energy of 100 MeV with irradiation fluence of 1013 -1014 ions/cm2 . It has been determined that change in magnitude of atom displacements from lattice sites is exponential, which is conditioned by defect overlap regions occurrence at fluence of 1014 ions/cm2 , followed by formation of a large number of migrating defects in structure, leading to crystal structure distortion and deformation due to chemical bonds rupture. In case of defect overlap areas generation, characteristic for irradiation fluences of 5 × 1013 - 1014 ions/cm2 , amorphous inclusions formation of more than 5% was observed, that leads to thermal conductivity decrease by (15-20)%.

Radiation effects in cerium doped Gd3(Al,Ga)5:O12 (or GGAG) single crystals irradiated by swift heavy ions with fluences ranging from 6·1010 to 2·1012 ions/cm2 have been studied. A stable strong induced absorption observed in the spectral range 200–350 nm correlates with the irradiation fluence. It is suggested that several centers are responsible for this induced absorption in GGAG single crystals and their possible origin (F-type centers and V-centers or holes trapped near cation vacancies) is proposed and discussed. The swift heavy ions irradiation strongly modifies the luminescence properties of GGAG, namely, the excitation spectra of the Ce3+ emission, which have been measured over a wide spectral range including vacuum ultraviolet diapason. In particular, it was shown that the formation of the stable radiation defects under swift heavy ions irradiation leads to the effective Ce4+ → Ce3+ transformation in the Mg2+ co-doped GGAG single crystals. The reasons leading to the alteration in the luminescence properties of irradiated GGAG single crystals are elucidated and discussed.

The paper presents the results of stability of the characteristic of overvoltage diodes under the action of neutron and gamma radiation. Nature of this paper is both experimental and theoretical. An original measuring system of extremely low measurement uncertainty was developed for the purpose of recording characteristics. Recording of volt-ampere and volt-ohm characteristics was performed in a completely new way based on the use of a single current pulse (which allows obtaining more reliable results than the methods recommended in the literature based on the use of DC). The obtained results are useful in all areas of engineering practice when there is a danger of simultaneous occurrence of various overvoltages and nuclear radiation. Theoretical interpretation has given some new interpretations of neutron-phonon and photon-phonon interpretations. [ABSTRACT FROM AUTHOR]

The effect of short-pulsed irradiation with 220 keV carbon ions for fluences of 2.2 × 1013 – 2.1 × 1015 cm−2 on the optical and electrical properties of titanium nitride films deposited by reactive magnetron sputtering on silicon and steel substrates has been studied. Relationships are obtained between the irradiation conditions and the parameters of interband absorption. A relationship has been established between the concentration of defects before and after irradiation, the degree of overlap of their levels and changes in the optical and electrical properties of the films. Reasons of high radiation resistance of the films are discussed. The optical and electrical properties of the films change during irradiation in two stages. The first stage is related to the annihilation of defects, the second stage is associated with their accumulation. Irradiation of films significantly slows down the rate of oxidation of their surface layers and stabilizes the electrical properties. [ABSTRACT FROM AUTHOR]

The paper considers the hydrogenation processes in Li2TiO3 ceramics under irradiation with protons with an energy of 500 keV and fluences of 1 × 1010–5 × 1017 ion/cm2. The choice of the type of irradiation, as well as the irradiation fluences, is based on the possibilities of modeling hydrogenation processes and studying the kinetics of structural changes caused by the accumulation of radiation damage. The choice of Li2TiO3 ceramics as objects of research is due to their prospects for using as blanket materials of thermonuclear reactors for the tritium production and accumulation. It was found that the formation of point defects and their subsequent evolution associated with the formation of complex compounds and the filling of pores, followed by the formation of gas-filled bubbles, the presence of which leads to a decrease in crack resistance and resistance to destruction of the near-surface layer. Based on the data on structural changes and evolution of the crystal lattice parameters, its swelling, a description of the destruction processes associated with hydrogenation in Li2TiO3 ceramics was proposed. Also, during the studies, it was found that at irradiation fluences above 1 × 1017 ion/cm2, the appearance of impurity inclusions characteristic of the TiO2 phase was observed, the presence of which indicates the crystal lattice destruction processes because of accumulation of radiation damage and deformations caused by them. Critical doses are established at which there is a sharp deterioration in strength and crack resistance, reflecting the resistance of ceramics to mechanical external influences. [ABSTRACT FROM AUTHOR]

The effect of proton irradiation on the structure, phase composition, defect state and nanohardness of Zr/Nb nanoscale multilayer coatings was investigated. Preservation of the Zr/Nb layered structure with 50 and 100 nm thick layers, was observed after irradiation with protons at 1720 keV energy and 3.4 × 1015, 8.6 × 1015 and 3.4 × 1016 ions/cm2 fluences, and the interfaces remained incoherent. In the Zr/Nb nanoscale multilayer coatings with individual layer thicknesses of 10 and 25 nm, there were insignificant fluctuations in interplanar distance, which were influenced by changes in irradiation fluence, and the interfaces were partially destroyed and became semicoherent. Changing irradiation fluence in the investigated ranges led to a decrease in the nanohardness of the Zr/Nb nanoscale multilayer coatings with individual layer thicknesses of 10–50 nm. Variable-energy positron Doppler broadening analysis revealed that these changes are primarily caused by peculiarities of the localization and accumulation of the embedded ions and do not cause a significant increase in the S-parameters of Zr/Nb nanoscale multilayer coatings with a layer thickness less than 100 nm.

The dependences of changes in the strength properties of nitride and carbide ceramics under high temperature irradiation with Kr15+ and Xe22+ heavy ions at irradiation doses of 1012–1015 ions/cm2 are presented in this work. The irradiation was chosen to simulate radiation damage processes that are closest to the real conditions of reactor tests in operating modes of increased temperatures. Polycrystalline ceramics based on AlN, Si3N4 nitrides, and SiC carbides were chosen as objects of research, as they have great prospects for use as a basis for structural materials for high-temperature nuclear reactors, as well as materials for nuclear waste disposal. During these studies the effect of radiation damage caused by irradiation with different fluences on the change in mechanical strength and hardness were determined, and the mechanisms causing these changes depending on the type of irradiated materials were proposed. The novelty of this study is in the results obtained determining the stability of the strength and thermophysical parameters of nitride and carbide ceramics exposed to high-temperature irradiation, which made it possible to determine the main stages and mechanisms for changing these parameters depending on the accumulated radiation damage. The relevance of this study consists not only in obtaining new data on the properties of structural materials exposed to ionizing radiation, but also in the possibility of determining the mechanisms of radiation damage in ceramics. [ABSTRACT FROM AUTHOR]

This article presents the experimental results of mechanical properties of fuel rod claddings from E110 zirconium alloy in the longitudinal direction that operated in fuel assemblies of VVER-1000 nuclear reactors to the fuel burnup of ~20 and ~70 MW d/kg U before and after post-radiation annealing at 380°C for 468 days. The changes in strength and plastic properties of the cladding in longitudinal direction were analyzed in comparison with its properties before and after irradiation and with their changes in the transverse direction. The changes in mechanical properties of the cladding are explained as a function of radiation damage of its structure. [ABSTRACT FROM AUTHOR]

Radiation damage is one of the significant factors limiting the operating time of many structural materials working under extreme conditions. One of the promising directions in the development of materials that are resistant to radiation damage and have improved physical and mechanical properties is the creation of nanoscale multilayer coatings (NMCs). The paper is devoted to the experimental comprehension of changes in the defect structure and mechanical properties of nanoscale multilayer coatings (NMCs) with alternating layers of Zr and Nb under irradiation. Series of Zr/Nb NMCs with different thicknesses of individual layers were fabricated by magnetron sputtering and subjected to H+ irradiation. The evolution of structure and phase states, as well as the defect state under proton irradiation, was studied using the methods of high-resolution transmission electron microscopy (HRTEM), X-ray diffraction analysis (XRD), glow discharge optical emission spectroscopy (GDOES), and positron annihilation spectroscopy (PAS). The layer-by-layer analysis of structural defects was carried out by Doppler broadening spectroscopy (DBS) using a variable-energy positron beam. To estimate the binding energy and the energy paths for the hydrogen diffusion in Zr/Nb NMCs, calculations from the first principles were used. When the thickness of individual layers is less than 25 nm, irradiation causes destruction of the interfaces, but there is no significant increase in the defect level, the S parameter (open volume defects amount) before and after irradiation is practically unchanged. After irradiation of NMC Zr/Nb with a thickness of layers 50 and 100 nm, the initial microstructure is retained, and the S parameter is significantly reduced. The GDOES data reveal the irregular H accumulation at the interface caused by significant differences in H diffusion barriers in the bulk of Zr and Nb multilayers as well as near the interface's region. [ABSTRACT FROM AUTHOR]

The formation and evolution of radiation defects and their effects on bending property of a single graphite under low energy helium atom implantation have been studied at atomic scale through molecular dynamics simulations. Various simple interstitial and vacancy defects are observed during the implantation process, which is a function of incident energy and cross section of helium-carbon interaction. Large defects are observed after continuous helium atom implantations. The effects of incident energy on the density, size and distribution of defects are analyzed in detail. Furthermore, the kinetic evolution process of radiation defects at different annealing temperatures have also been simulated, including the migration, aggregation, transformation, coalescence, and self-healing. The large defect clusters, crossing several carbon layers, have been confirmed to be the primary reasons that affect the bending property of graphite. All these results provide a new understanding for further applications of graphite in nuclear reactors. [Display omitted] [ABSTRACT FROM AUTHOR]

The key aim of this paper is to study the presence effect of LiO impurity phases in Li2ZrO3 ceramics on the resistance to helium swelling and structural degradation during implanted helium accumulation in the near-surface layer structure. The hypothesis put forward is based on a number of scientific papers, in which it was reported that the presence of two or more phases in lithium-containing ceramics led to a decrease in the rate of radiation damage and gas swelling due to the presence of additional interfacial boundaries that prevent the point defect accumulation. As a result of the evaluation of the crystal structure deformation, it was found that the presence of the LiO impurity phase in the structure of Li2ZrO3 ceramics led to a threefold decrease in the deformation of the crystal lattice due to helium swelling at doses of 5 × 1017–5 × 1018 ion/cm2. At the same time, the nature of the crystal lattice deformation for different ceramic types is different: in the case of Li2ZrO3 ceramics, an anisotropic distortion of the crystal structure is observed, in the case of Li2ZrO3/LiO ceramics, the crystal lattice deformation has an isotropic nature. [ABSTRACT FROM AUTHOR]

The effects of radiation on 3CG110 PNP bipolar junction transistors (BJTs) are characterized using 50-MeV protons, 40-MeV Si ions, and 1-MeV electrons. In this paper, electrical characteristics and deep level transient spectroscopy (DLTS) are utilized to analyze radiation defects induced by ionization and displacement damage. The experimental results show a degradation of the current gain and an increase in the types of radiation defect with increasing fluences of 50-MeV protons. Moreover, by comparing the types of damage caused by different radiation sources, the characteristics of the radiation defects induced by irradiation show that 50-MeV proton irradiation can produce both ionization and displacement defects in the 3CG110 PNP BJTs, in contrast to 40-MeV Si ions, which mainly generate displacement defects, and 1-MeV electrons, which mainly produce ionization defects. This work provides direct evidence of a synergistic effect between the ionization and displacement defects caused in PNP BJTs by 50-MeV protons. [ABSTRACT FROM AUTHOR]

The paper presents the results of study of the effect of irradiation with heavy Ar8+, Kr15+ and Xe22+ ions with energies of 70, 150 and 230 MeV, respectively, on the stability of mechanical properties, in particular, hardness and wear resistance, as well as thermal conductivity, depending on irradiation fluence. The interest in this research topic is due to the wide prospects for the use of nitride ceramics as the basis for structural materials for nuclear and thermonuclear energy, exposed to ionizing radiation, in particular, particles -- fragments of fission of uranium nuclei. During the experiments, dose dependences of changes in strength, mechanical and heat-thermal conductive properties were obtained. It has been established that the decrease in thermal conductivity has a pronounced dependence on both the energy of incident ions and the radiation dose. The obtained dependencies can later be used in the forecasting and design of nuclear power plants, in which it is planned to replace traditional materials with new classes, including ceramics or composite structures. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of changes in the strength properties of AlN ceramics, in particular, the dry friction coefficient and parameters of wear resistance and surface defectiveness, depending on the dose of irradiation with heavy Xe22+ ions with an energy of 200 MeV. Interest in these ceramics is due to their high thermal conductivity, hardness and wear resistance, as well as excellent insulating properties, which makes them promising candidate materials in nuclear power, rocket engineering and microelectronics. At the same time, the operation of these ceramics under conditions of external influences, such as mechanical friction, pressure on the surface, as well as the effect of ionizing radiation, requires additional research and obtaining new data on the stability and retention of properties during the entire service life. During the studies carried out, it was found that at low irradiation doses of 1010-1011 ions/cm2, which are characterized by the formation of single point defects and a low probability of surface degradation as a result of the initialization of gas swelling processes, the dry friction coefficient practically does not change, which indicates ceramics high mechanical friction resistance. However, an increase in the irradiation fluence up to 1012 ion/cm2, which is characterized by the processes of overlapping radiation-induced damaged areas, a deterioration in the dry friction coefficient is observed after 15000 test cycles, which indicates fatigue wear of the ceramic surface and degradation as a result of external influences. [ABSTRACT FROM AUTHOR]

This work is devoted to the study by computer simulation of the mechanisms of the influence of radiation defects, arising under the influence of neutron irradiation, on the changes in electrical properties: resistivity ρ, electron mobility μn, lifetime of nonequilibrium electrons τn and holes τp in Cd0.9Zn0.1Te and charge collection efficiency η of uncooled ionizing radiation detectors based on this material. Radiation defects, which are corresponded by deep energy levels in the band gap, act as trapping centers of nonequilibrium charge carriers, noticeably affect the degree of compensation by changing ρ of the detector material, the recombination processes, decreasing τn and τp, and also the scattering of conduction electrons, decreasing μn, that ultimately can cause degradation of the charges collection efficiency η. The specific reasons for the deterioration of the electrophysical and detector properties of this semiconductor under the influence of neutron irradiation were identified, and the main factors affecting the increase in the resistivity of Cd0.9Zn0.1Te during its bombardment by low-energy and high-energy neutrons, leading to complete degradation of the recording ability of detectors based on this materials, were found. The recombination of nonequilibrium charge carriers is noticeably stronger than the decrease in μn affects the degradation of detector properties, therefore, the effect of recombination processes at deep levels of radiation defects on the degradation of τn, τp, and η of detectors based on Cd0.9Zn0.1Te was studied. A comparative analysis of the properties of Cd0.9Zn0.1Te with the previously studied CdTe:Cl was made. An attempt was made to explain the higher radiation resistance of Cd0.9Zn0.1Te compared to CdTe:Cl under neutron irradiation by the influence of the radiation self-compensation mechanism with participation of deep donor energy levels: interstitial tellurium and tellurium at the site of cadmium. In addition, the rate of recombination at defect levels in Cd0.9Zn0.1Te is, ceteris paribus, lower than in CdTe:Cl due to the smaller difference between the Fermi level and the levels of radiation defects in cadmium telluride. The relationship between the band gaps of Cd0.9Zn0.1Te and CdTe:Cl, the concentration of radiation defects, the Fermi level drift during irradiation, and the radiation resistance of the detectors were also noted. The important role of purity and dopant shallow donor concentration in initial state of the detector material is indicated.