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4th Generation high-temperature gas-cooled nuclear reactors (HTGR) are regarded as possible sources of industrial heat in Poland and Europe, allowing for a substantial reduction of the dependency on gas and coal import. It is mainly due to their safety of use, reliability and economy in a current energetic crisis. In this work, graphite, as a primary construction material and neutron moderator in HTGR, was evaluated before and after ion irradiation since its properties depend on the material's structure and purity. Commercial graphite materials (IG-110, NBG-17) and the laboratory's in-home material were chosen for the exemplary samples. The structural damage in HTGR was simulated with energetic Ar+ and He+ ions with fluencies from 1E12 to 2E17 ion/cm2. Raman imaging was chosen to assess radiation damage build-up: the crystallites' evolution, occurrence and types of defects. The recorded evolution showed stronger disordering of the material with heavier Ar+ ions than with He+.

In this study structural and mechanical properties of a 1 μm thick Al2O3 coating, deposited on 316L stainless steel by Pulsed Laser Deposition (PLD), subjected to high energy ion irradiation were assessed. Mechanical properties of pristine and ion-modified specimens were investigated using the nanoindentation technique. A comprehensive characterization combining Transmission Electron Microscopy and Grazing-Incidence X-ray Diffraction provided deep insight into the structure of the tested material at the nano- and micro-scale. Variation in the local atomic ordering of the irradiated zone at different doses was investigated using a reduced distribution function analysis obtained from electron diffraction data. Findings from nanoindentation measurements revealed a slight reduction in hardness of all irradiated layers. At the same time TEM examination indicated that the irradiated layer remained amorphous over the whole dpa range. No evidence of crystallization, void formation or element segregation was observed up to the highest implanted dose. Reported mechanical and structural findings were critically compared with each other pointing to the conclusion that under given irradiation conditions, over the whole range of doses used, alumina coatings exhibit excellent radiation resistance. Obtained data strongly suggest that investigated material may be considered as a promising candidate for next-generation nuclear reactors, especially LFR-type, where high corrosion protection is one of the highest prerogatives to be met.

The article discusses the legal and administrative regulations regarding the prevention and control of infectious diseases. The author puts forward and justifies the thesis that the SARS-CoV-2 coronavirus epidemic (COVID-19 disease) has exposed significant imperfections (and partly deficiencies) of the above-mentioned regulations, and at the same time revealed the effects of – sometimes insufficient – theoretical reflection on administrative law and the methods of reception of its assumptions and theoretical structures into the provisions of this law. Against this background, particular attention was paid to the construction of the special state as a (separate and independent) institution of material administrative law, as well as to issues concerning, inter alia, administrative regulations, general administrative acts, administrative enforcement of non-pecuniary obligations, administrative proceedings, criminal-administrative law, and social (digital) exclusion in administrative law. The considerations are summed up by the statement that administrative law – both in practical and theoretical terms – has turned out to be insufficiently prepared for an epidemic of an infectious disease in general, and even more so for an epidemic of a scale such as that caused by the SARS-CoV-2 coronavirus.

A new tool for Monte Carlo simulation of ion channeling in crystals is described. The recently developed McChasy2 code follows the algorithm used previously in the McChasy program, but is well suited for simulations in large crystalline samples. The state of works on the validation of the code, and the possibilities of the new code for supplementing molecular dynamics with a tool supporting the experimental analysis of crystalline structures are presented and discussed.

The article deals with the subject of collegiality and monocracy in the structure of local government authorities in Poland. The author begins his considerations with the characteristics of the collegial and monocratic form of organization of administrative organs. It indicates their essence, advantages and disadvantages and the related possibilities of their application in public administration. The next part of the study analyzes the existence of collegial and monocratic forms in the organizational system of local government authorities, which are treated in a broader sense than just as organs of individual local government units. The author indicates collegial and monocratic structures, emphasizing that the former are clearly preferred, and discusses the postulate of extending the monocratic form to all local government executive bodies; also draws attention to the need for a legal solution to the emancipation of monocratic offices of heads of collegial organs towards the separate and independent offices. An important role is played by the presentation and evaluation of various collegial bodies with which local government organs are enclosed. The considerations end with summarizing reflections, in which the timeliness and importance of the issues under consideration is emphasized, along with the listing of the most important issues.

The main aim of the work was investigation of the graphene resistance on mechanical scratch after ion beam bombardment. The CVD graphene on the glass substrate was used. Bombardment of graphene by beams of helium and nitrogen ions of energy 100 keV was applied. Density of ion induced defects in graphene was evaluated using Raman spectroscopy. The polymer indenter was applied for scratch test. Increase of the scratch resistance of the graphene after ion beam bombardment was observed. Scratch resistance of the graphene layer increases with increasing density of defects induced by helium and nitrogen ions. The shape of graphene ribbons exfoliated during scratch test suggests that increase of graphene scratch resistance is accompanied with improvement of graphene adhesion to the substrate. It suggests that ion beam induced defects may be responsible for observed increasing of both graphene scratch resistance ad graphene adhesion to the substrate.

The main aim of this work is to get a deeper insight into the problem of insulation properties of materials exposed to radiative environment, namely to compare hardness and electrical resistivity in selected polymers which may be used as electric insulations. The long term objective of the work is to develop a method that can be used for a fast screening of insulation properties without disconnecting the cables from the installation. It is believed that hardness measurements can provide an indication of the insulation resistance, and can hence allow for fast checking of the safety of the electrical installation. A short discussion of the structural effects caused by irradiation with energetic light ions (modeling ionizing radiation) is followed by the analysis of mechanical and electrical characteristics of irradiated polymers aiming at searching for the correlation between these two properties. The results obtained show that hardness may serve the purpose of an indicator of early stages of electrical insulation deterioration in polymers and elastomers.

The influence of Ar+ ion irradiation on structural and nanomechanical properties of Yttria Stabilized Zirconia (YSZ) single crystals were studied. Specimens grown in three crystallographic orientations 〈1 0 0〉, 〈1 0 0〉 and 〈1 1 1〉 were irradiated at room temperature with 160 keV Ar-ions up to 3 fluences: 1 × 1014, 1 × 1015 and 1 × 1016 cm−2. Structural properties of the modified layers were measured by means of Grazing Incidence X-ray Diffraction (GI XRD) and Raman Spectroscopy techniques, whereas nanomechanical properties were asessed by using nanoindentation technique. Obtained results revealed shifts of the characteristic peaks and hardening effect in the function of Ar-ion fluence. Reported changes originate from at least two phenomena: (i) creation of radiation defects and (ii) local increase of stress induced by damage created by incoming ions – which magnitude may depend on crystallographic orientation.

The M4F project brings together the fusion and fission materials communities working on the prediction of radiation damage production and evolution and their effects on the mechanical behaviour of irradiated ferritic/martensitic (F/M) steels. It is a multidisciplinary project in which several different experimental and computational materials science tools are integrated to understand and model the complex phenomena associated with the formation and evolution of irradiation induced defects and their effects on the macroscopic behaviour of the target materials. In particular the project focuses on two specific aspects: (1) To develop physical understanding and predictive models of the origin and consequences of localised deformation under irradiation in F/M steels; (2) To develop good practices and possibly advance towards the definition of protocols for the use of ion irradiation as a tool to evaluate radiation effects on materials. Nineteen modelling codes across different scales are being used and developed and an experimental validation programme based on the examination of materials irradiated with neutrons and ions is being carried out. The project enters now its 4th year and is close to delivering high-quality results. This paper overviews the work performed so far within the project, highlighting its impact for fission and fusion materials science. Peer Reviewed L. Malerba a,*, M.J. Caturla b, E. Gaganidze c, C. Kaden d, M.J. Konstantinovi´c e, P. Olsson f, C. Robertson g, D. Rodney h, A.M. Ruiz-Moreno i, M. Serrano a, J. Aktaa c, N. Anento j, S. Austin i, A. Bakaev e, J.P. Balbuena b, F. Bergner d, F. Boioli k, M. Boleininger l, G. Bonny e, N. Castin e, J.B. J. Chapman l, P. Chekhonin d, M. Clozel m, B. Devincre k, L. Dupuy g, G. Diego a, S.L. Dudarev l, C.-C. Fu g, R. Gatti k, L. G´el´ebart g, B. G´omez-Ferrer n, D. Gonçalves g, C. Guerrero a, P.M. Gueye n, P. H¨ahner i, S.P. Hannula o, Q. Hayat p, M. Hern´andez-Mayoral a, J. Jagielski m, N. Jennett p, F. Jim´enez a, G. Kapoor d, A. Kraych h, T. Khvan e,q, L. Kurpaska m, A. Kuronen r, N. Kvashin j, O. Libera s, P.-W. Ma l, T. Manninen o, M.-C. Marinica g, S. Merino a, E. Meslin g, F. Mompiou t, F. Mota a, H. Namburi s, C.J. Ortiz a, C. Pareige n, M. Prester u, R.R. Rajakrishnan t, M. Sauzay g, A. Serra j, I. Simonovski i, F. Soisson g, P. Sp¨atig v, D. Tanguy h, D. Terentyev e, M. Trebala o, M. Trochet g, A. Ulbricht d, M.Vallet g, K. Vogel d, T. Yalcinkaya w, J. Zhao r a Centro de Investigaciones Energ´eticas, Medioambientales y Tecnol´ogicas (CIEMAT), Madrid, Spain b Universidad de Alicante, San Vicente del Raspeig, Spain c Karlsruher Institut für Technologie (KIT), Karlsruhe, Germany d Helmholtz-Zentrum Dresden-Rossendorf Ev (HZDR), Rossendorf, Germany e Studiecentrum voor Kernenergie / Centre d’´Etude de l’´Energie Nucl´eaire (SCK CEN), Mol, Belgium f KTH Royal Institute of Technology, Stockholm, Sweden g Universit´e Paris-Saclay, Commissariat `a l’´Energie Atomique et aux ´Energies Alternatives (CEA), Gif-sur-Yvette, France h Institut Lumi`ere Mati`ere (ILM), Centre National de la Recherche Scientifique, Lyon, France i Joint Research Centre (JRC)- European Commission, Petten, the Netherlands j Universitat Polit`ecnica de Catalunya, Barcelona, Spain k Laboratoire d’Etude des Microstructures (LEM), Centre National de la Recherche Scientifique, Chˆatillon, France l United Kingdom Atomic Energy Authority (UKAEA), Culham, UK m Narodowe Centrum Badan Jadrowych (NCBJ), Swierk, Poland n Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Mat´eriaux, 76000 Rouen, France o Aalto University, Espoo, Finland p Coventry University, UK q Universit´e de Li`ege, Belgium r Helsingin Yliopisto, Helsinki, Finland s Centrum Vyzkumu ˇReˇz S.R.O. (CVR), ˇReˇz, Czech Republic t Centre pour l’´Elaboration Elaboration de Mat´eriaux et pour l’´Etude des Structures (CEMES), Centre National de la Recherche Scientifique, Toulouse, France u Institut za Fiziku, Zagreb, Croatia v Paul Scherrer Institut (PSI), Villingen, Switzerland w Middle East Technical University (METU), Ankara, Turkey

The main goal of the McChasy code, in general, is to reproduce Rutherford Backscattering Spectrometry experimental spectra recorded in channeling direction (RBS/C) by simulating He-ions travelling inside crystalline structures and to calculate the probability of the backscattering process. The 2.0 version of the code provides the possibility to simulate channeling spectra in large (ca. 108 atoms) arbitrary structures that are created based on crystallographic data or Molecular Dynamic (MD) calculations. In this work, we present the current status of the code and the results of recent investigations of extended structural defects (edge dislocations and dislocation loops) formed inside nickel (Ni) single crystals. Two ways of modelling extended defects are described: one developed using the McChasy code (Peierls-Nabarro approach) and the other one obtained by modification and thermalization of Ni structures by MD (LAMMPS code). The atomic local environment was studied qualitatively and quantitatively by the local projectile-flux density distributions around the defects.

In this study, mechanical properties of two ODS steels, characterized by the same chemical composition yet manufactured by using two different production methods, namely High Isostatic Pressure (HIP) and Hot Extrusion (HE), have been investigated at high temperature by nanoindentation technique. The hardness of the material was evaluated from room temperature up to 600 °C, while initial creep behavior was estimated at room temperature and at 600 °C. In order to better understand the mechanical response of the materials, especially impact of the surface effects, mechanical maps (hardness and reduced young modulus) have been created.

The paper presents recent studies focused on improving friction and wear properties of acrylonitrile-butadiene rubber (NBR). The main objective of the presented study is to investigate impact of wide range of ions, irradiated with different energies and fluencies and find correlation between friction coefficient, hardness and mechanical strength of NBR-type elastomers. In this study, structural properties of pristine and irradiated elastomers were assessed by using Scanning Electron Microscopy (SEM), whereas the nano-mechanical properties were studied by means of nanoindentation technique and wear properties by pin-on-disc friction test.

Conductive graphene electrode of large area is required for some applications like for example photovoltaics or touch screens. Such large area graphene membrane needs specific test methods to assess defects which may obstacle its performance. In this work the infrared imaging of Joule heated graphene was proposed to estimate its uniformity and mechanical continuity. Thermal signatures of the typical mechanical defects like scratches and local resistivity inhomogeneity were identified. Distribution of the heat emission around such defects were simulated using finite elements method and then experimentally verified by recording of thermal landscape around the corresponding real graphene defects. Proposed method gives micrometric resolution and ability to inspection of large area electrodes depending on applied optics. Presented results give suggestions how graphene imperfections generate observed hot points related to graphene layer defects.

The paper presents the effect of He+ ion irradiation of selected polymeric materials: poly(tetrafloroethylene), poly(vinyl chloride), ethylene-propylene-diene monomer rubber, nitrile-butadiene rubber, styrene-butadiene rubber, and natural rubber, on their chemical composition, physical structure, and surface topography. The modification was studied by scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and differential scanning calorimetry. Irradiation with a high-energy ion beam leads to the release of significant amounts of hydrogen from the surface layer, resulting in an increase in cross-linking that manifests itself by shrinkage of the surface layer, which in turn causes significant stresses leading to the formation of a crack pattern on the polymer surface. The development of microroughness is combined with oxidation. Shallow range of the ions makes the modified layer “anchored” in the substrate via bulk macromolecules, assuring its good durability and adhesion to elasto-plastic substrates. Changes in the surface layer were manifested by the modification of functional properties of the polymers. The hardness of the layer subjected to the ion irradiation process increases even up to 10 times. After modification with the ion beam, a significant decrease in frictional forces was also observed, even up to 5–6 times. The microscopic analysis of wear traces confirmed that the wear resistance also significantly increased. However, ion bombardment of polymeric materials caused a reduction in their mechanical strength (despite the range limited to the surface layer of the order of micrometers) and electrical resistance, which has a negative impact on the possibility of using the materials in some applications.

The damage-induced voltage alteration (DIVA) contrast mechanism in scanning electron microscope (SEM) at low electron energy has been presented as a fast and convenient method of direct visualization of increased resistivity induced by energetic ions irradiation in gallium nitride (GaN). Epitaxially grown GaN layers on sapphire covered with a metallic masks with etched windows were subjected to He2+ irradiations at 600 keV energy. The resulting two-dimensional damage profiles at the samples cross-sections were imaged at SEM at different e-beam currents and scan speeds. The gradual development of image contrast was observed with the increase of cumulative charge deposited by electron beam irradiation, to finally reach the saturation level of the contrast related to the local resistivity of the ion-irradiated part of GaN. The presented method allows one to directly visualize the ion-irradiated zone even for the lowest resistivity changes resulting from ion damage, i.e. all levels of insulation build-up in GaN upon irradiation with ions. Taking into account that it is not possible to apply the etch-stop technique by wet chemistry to GaN, it makes the presented technique the only available method of visualization of highly resistant and insulating regions in GaN-based electronic devices. Main aim of the presented work is to get a deeper insight into a DIVA contrast in GaN with the special emphasize to discuss the role of rastering speed and electron beam current, i.e. details of charge build-up ion the sample surface.

The effects of consolidation process and low-energy ions (Ar+) irradiation on mechanical properties of 12% Cr, 2% W, 0.25% Ti, 0.25% Y2O3 (%wt.) ODS RAF steel were investigated. Three types of samples, fabricated with different methods: Spark Plasma Sintering (SPS), Hot Isostatic Pressing (HIP) and Hot Extrusion (HE) were studied. The microstructure of obtained specimens were characterized by using High Resolution Scanning Electron Microscopy (HR-SEM) and Electron Backscatter Diffraction Analysis (EBSD) techniques. Each material was submitted to low energy (160 keV) Ar+ ion irradiation with fluences: 1014, 1015 and 1016 [ions/cm2] what corresponds to ~4 dpa of material damage. Mechanical properties were evaluated in micro- and nano-scale, using Vickers micro-hardness HV0.1 and nanoindentation method (NI). Conducted research shows that materials manufactured by using SPS and HIP processes exhibits very similar mechanical properties, although implementation of the first technique provide slightly better mechanical parameters of the specimen. Moreover, conducted in different volumetric scales experiments show that similar results were obtained by different mechanical test methods.

The main objective of this work is to study the properties of a new generation of rubbers characterized by an increased strength of the material (by adding graphene flakes to carbon black used as a filler) and to improve the surface properties (by using ion irradiation as a surface treatment technique). Most of the results were obtained for an acrylonitrile-butadiene rubber (NBR) with about 40% weight content of carbon black/graphene filler. The results point that even a relatively small amount (a few wt%) of graphene flakes to carbon black filler leads to a significant increase of the rending resistance of the elastomer. Ion irradiation of pristine and/or graphene-doped elastomer leads to a drastic release of hydrogen atoms from the surface layer. In consequence a thin, carbon-rich layer is formed at the rubber surface. This layer is characterized by a high hardness (roughly ten times harder than the unirradiated material), an improved hydrophilicity and, what is most important, a 5–6 times lower friction coefficient and a drastically increased wear resistance. The ion-irradiated layer may act also as a protective barrier limiting the oxygen diffusion into the material bulk, hence leading to an improvement of the resistance to ageing of surface treated rubbers.

In contrast to single crystalline materials a quantitative determination of defect formation in polycrystals is challenging. Here we use low-energy (3 keV) cathodoluminescence (CL) for structural characterization of single and polycrystalline magnesium aluminate spinel (MgAl2O4) exposed to irradiation with 300 keV Ar+ ions at room temperature in a wide fluence range of 1 × 1012–2 × 1016 cm−2. The results for single crystalline materials are also compared with conventional Rutherford Backscattering and Channeling spectrometry (RBS/C). It is demonstrated that damage formation in both single and polycrystalline spinels exhibits a multi-step character where polycrystalline material is more susceptible to ion irradiation. The results also imply that the low-energy CL is more sensitive to low damage levels as compared to RBS/C and it can be efficiently used as a complementary tool showing new perspectives in the damage accumulation studies in single- and polycrystalline materials.

In the present work, the effects of the fabrication method on mechanical and structural properties of 12%Cr, 2%W, 0.25%Ti, 0.25%Y2O3 steels were investigated. Materials obtained by Spark Plasma Sintering (SPS), Hot Isostatic Pressing (HIP) and Hot Extrusion (HE) methods were studied. The microstructure was characterized by using Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction analysis (EBSD). Mechanical properties of the studied samples were evaluated by using Vickers micro hardness HV0.1, Small Punch Test (SPT) and nanoindentation (NI) methods. The analysis revealed that samples manufactured via HIP and SPS processes exhibit very similar properties, whereas SPS method produces material with slightly lower hardness. In addition, significantly lower mechanical properties of the specimens after HE process were observed. The study described in this article addresses also the problems of mechanical parameters measured in micro- and nano-scale experiments and aims to identify possible pitfalls related to the use of various manufacturing technologies.

In this study structural and nanomechanical properties of polytetrafluoroethylene (PTFE) used as a gasket in the nuclear reactor have been deeply investigated. In order to reveal structural changes caused by long-term pressure, temperature and irradiation (possibly neutron and gamma), methods such as SEM, X-ray diffraction and Raman Spectroscopy have been used. Nanomechanical properties such as Young Modulus and hardness were investigated by means of the nanoindentation technique. Presented study confirmed the influence of working (radiative) environment on the functional properties of PTFE. The results of Raman spectroscopy and X-ray diffraction techniques revealed shift of the major band positions and band intensities increase. Moreover, changes of hardness and Young Modulus values of the irradiated material with respect to the virgin specimen have been recorded. This phenomenon can be attributed to the modifications in crystallinity of the material. Presented work suggest that morphology of the irradiated material altered from well-ordered parallel fibers to more dense and thicker ones.

The effect of ion implantation on mechanical and structural properties of 12%Cr ODS steel have been investigated. Specimens were submitted to single (He+ or Fe+) and dual ion beam (He+ and Fe+) implantation campaigns. Modification of three mechanical parameters: hardness, Young modulus and yield strength were characterized by means of nanoindentation technique. Structural properties were measured by using Grazing Incidence X-ray Diffraction (GIXRD) method. Correlation between obtained mechanical and structural results have been found. Recorded results show that ion-irradiation causes hardening effect which may be associated with creation of radiation defects and dislocation loops. The weakest effects have been observed for single He-ion implantation, whereas the dual beam irradiation led to significant change of all mechanical parameters. During structural analysis, small shifts of α-Fe peaks have been observed. Reported structural changes can be attributed to the effect of local stress introduced during ion irradiation.

The damage-induced voltage alteration (DIVA) contrast mechanism in scanning electron microscope (SEM) has been studied in broad range of the primary electron beam energies, with a special emphasis on the ultra-low energy range. The SEM imaging contrast related to resistivity changes in the In(0.55)Al(0.45)P irradiated with He2+ ions of 600 keV was subjected to an analysis in a range of 10 keV down to 10 eV of primary electron energies. The problem of specimen charging in ultra-low energy range and its effect on the contrast in SEM images has been tackled for the first time. Contrary to expectations based on the classical total emission yield approach, the potentials formed at the highly resistive part of irradiated area led to dramatic increase in the intensity of registered signal for primary electron energies below E1, which can be explained as signal saturation due to potential on the specimen surface acting as repeller for primary electrons. Nevertheless, the experimental data presenting the influence of the beam energy on the potential formation on the surface of an insulating material under electron irradiation have been presented for the first time in ultra-low energy regime.

The influence of low energy ion irradiation on mechanical and structural properties of Oxide Dispersion Strengthened (ODS) Reduced Activation Ferritic (RAF) steels were investigated using Nanoindentation (NI), High Resolution Scanning Electron Microscopy (HR SEM) and Energy Dispersive X-ray Spectroscopy (EDS) techniques. ODS samples were manufactured by means of High Isostatic Pressing (HIP) technique and irradiated at room temperature with 320 keV Ar 2+ ions up to fluences reaching 1 × 10 16 cm −2 . The results revealed fast increase of nanohardness in the function of two dependencies: (i) vanadium addition and (ii) ion fluence range. Furthermore, along with increasing vanadium content, the increase in the number of ∼100 nm sized precipitates consisting of Cr- O -V and Cr-C-V with small amounts of alloying elements (Ti, Al, W) have been observed. Simultaneously, the presence of nano-precipitates, with average size below 10 nm has been recorded. Conducted research confirms that their number decreases with increasing V content. The reported hardening effect is most probably related to: (i) quantity and size of precipitates identified as chromium-vanadium oxides and carbides with addition of alloying elements and (ii) level of damage created by ion irradiation.

An effect of Ar-ion irradiation on nanomechanical and structural properties of YSZ single crystals at room temperature was investigated. In order to simulate the radiation damage, the Ar-ions with 160 keV energy were implanted into the YSZ single crystals grown in (1 0 0), (1 1 0) and (1 1 1) crystallographic directions with the fluences ranging from 1 × 10 14 to 1 × 10 16 ion/cm −2 . Nanomechanical properties were measured by means of nanoindentation technique. The measurements were performed under 1, 2 and 3 mN loads which corresponded from ∼20 up to ∼50% of the total thickness of modified layer. Structural properties of the implanted layer were studied by Grazing Incidence X-ray Diffraction (GIXRD) and Raman Spectroscopy techniques. The obtained results revealed that mechanical (hardness and Young modulus) and structural properties (recorded peak shift’s) change with Ar-ion fluence. Recorded material hardening and peak shifts were associated with the local increase of residual stress and creation of radiation defects. Presented study suggest that mechanical changes induced by ion irradiation can be correlated with structural response of the specimen (even in the case of very thin layers).

The CVD graphene deposited on the glass substrate was bombarded by molecular carbon ions C 3 + C 6 + hydrocarbon ions C 3 H 4 + and atomic ions He + , C + , N + , Ar + , Kr + Yb + . Size and density of ion induced defects were estimated from evolution of relative intensities of Raman lines D (∼1350 1/cm), G (∼1600 1/cm), and D′ (∼1620 1/cm) with ion fluence. The efficiency of defect generation by atomic ions depend on ion mass and energy similarly as vacancy generation directly by ion predicted by SRIM simulations. However, efficiency of defect generation in graphene by molecular carbon ions is essentially higher than summarized efficiency of similar group of separate atomic carbon ions of the same energy that each carbon ion in a cluster. The evolution of the D/D′ ratio of Raman lines intensities with ion fluence was observed. This effect may indicate evolution of defect nature from sp3-like at low fluence to a vacancy-like at high fluence. Observed ion graphene interactions suggest that the molecular ion interacts with graphene as single integrated object and should not be considered as a group of atomic ions with partial energy.

Ion induced defect generation in graphene was analyzed using Raman spectroscopy. A single layer graphene membrane produced by chemical vapor deposition (CVD) on copper foil and then transferred on glass substrate was subjected to helium, carbon, nitrogen, argon and krypton ions bombardment at energies from the range 25 keV to 100 keV. A density of ion induced defects and theirs mean size were estimated by using Raman measurements. Increasing number of defects generated by ion with increase of ion mass and decrease of ion energy was observed. Dependence of ion defect efficiency (defects/ion) on ion mass end energy was proportional to nuclear stopping power simulated by SRIM. No correlation between ion defect efficiency and electronic stopping power was observed.

A composite rod, designed for the neutron absorption in nuclear research reactors or Nuclear Power Plants (NPPs), was synthesized by ball milling and subsequent Hot Isostatic Pressing (HIP-ing), similarly to the one reported in Ref. [3]. Its core consists of the oxide dispersion strengthened ferritic Fe-Cr matrix and 40 wt.% of TiB 2 reinforcement, surrounded by a Ti tubing/cladding with a functionally graded interface layer. The Specific Surface Area (SSA) for the ball-milled pre-alloyed powders increases from 0.64 to 2.92 m 2 /g and XRD shows that the crystallite/grain size of TiB 2 is ∼38 nm. Berkovich nanoindentation study after irradiation with 160 keV He + ions at a fluence up to 1 × 10 17 He + /cm 2 shows an initial hardening effect at fluences of 1 × 10 15 and 1 × 10 16 ions/cm 2 . Hardness and elastic modulus of the Fe-Cr -TiB 2 core rapidly drops when the fluence reaches 1 × 10 17 ions/cm 2 . The Ti cladding seems to be relatively impervious to increased radiation fluence since its hardness and elastic modulus change very slightly with increasing ion fluence. The observed changes in the mechanical properties are discussed in terms of vacancy/dislocation loops and He bubble formation in the irradiated microstructure. Although the He-vacancy complexes are widely regarded as being immobile, it is hypothesized here, based on the grazing incidence XRD (GI XRD), that interstitial helium diffuses outward through the boundaries of the (100) hcp-TiB 2 nanograins. As a result, the relaxation of compressive strains due to high concentration of vacancies in a nanograin crystalline lattice finally leads to the hcp-TiB 2 unit cell contraction.

Since more than half century ion beams are used for modification of functional properties of various materials: after semiconductors, metals and ceramics ion irradiation appeared recently as an interesting method of modification of organic materials, especially for friction and wear properties. Among polymeric materials the newest area of applications of ion beams is their use for modification of elastomers, commonly known as rubbers. Main structural effect caused by heavy ions in polymers is a massive loss of hydrogen from the surface layer, this leads to a smoothening and shrinking of the sample surface. The paper describes the results obtained in several rubbers modified by ion beams. Both, pristine and graphene-reinforced rubber samples were used, graphene doping led to the strengthening of the material bulk whereas ion irradiation allowed for surface property improvement. In the first part of the paper the hydrogen release from irradiated elastomers is shortly presented. Mechanical properties (hardness and friction) are discussed in the second part.

Single layer graphene grown by chemical vapor deposition (CVD) method on Cu foil and then transferred onto a borosilicate glass substrate was used in the experiments. The graphene samples were irradiated by singly charged ions of helium, nitrogen, argon or krypton at the energy of 100 keV up to fluence ranging from 1 × 1011 cm− 2 to 1 × 1016 cm− 2. Raman spectroscopy was used for the detection of defect size and density in graphene caused by ion irradiation. The ion induced defect size and density were determined from the Raman spectra measurements. The applicability of the SRIM code for simulation of defects generation by ions in graphene was tested. Finally, the controlled generation of the defects in graphene by using ion implantation was verified.

Metal-oxide interfaces phases developed during high temperature oxidation on pure zirconium and zirconium alloy (Zr-1.0%Nb) were investigated. Main objective of the study was to elucidate the results coming from previous structural studies and better understand the process of zirconium alloys oxidation. Samples were prepared by high temperature oxidation at 600 °C in air under normal atmospheric pressure. Afterwards, samples were examined by combined methodology of SEM/FIB/EBSD and EDS techniques. Implementation of these techniques revealed complexity of studied systems and confirmed the presence of continuous, rich in tetragonal phase oxide layer located in the proximity of the zirconium substrate. This region is probably characterized by lower amount of oxygen than the external part of the oxide scale. According to the EDS analysis, reported oxide scale is most likely composed of stoichiometric ZrO 1:1. In order to explain observed phenomena, the combined effects of compressive stress and stoichiometry level were taken into account.

The influence of ion irradiation on nanomechanical properties of Gd 2 Zr 2 O 7 pyrochlore have been studied. The polycrystalline samples were irradiated at room temperature with 320 keV Ar ions with fluences from 2 × 10 14 to 1 × 10 16 ions/cm 2 . Nanomechanical properties of grains and grains boundaries were measured by means of nanoindentation technique. The measurements were performed in the centers of the grains and at the grain boundaries and point to the conclusion that grain boundary region is usually characterized by higher hardness and Young’s modulus than the center of the grain. The analysis performed suggests that the stress induced effect related to the transition to anion-deficient fluorite structure leads to the increase of recorded hardness values and may be considered as primary source of hardening. Studied phenomenon depends on the irradiation fluence and may serve as an indicator of the structure modification in the irradiated sample. Finally, nanomechanical properties of irradiated grain boundaries were interpreted in the frames of incorporation of foreign species near grain boundary.

Graphite is known as a material with excellent thermo-mechanical, structural and neutron moderation properties. It is currently used as a core structural component for High Temperature Gas Cooled Reactor (HTGR). It is due to the fact that graphite has been extensively tested and proved to satisfy most of HTGR operating requirements. However, one question still remain unclear. Graphite, depending from the manufacture method, type and purity shows different mechanical and structural properties. In addition to that, literature data is poor in comparative studies of current and used in the past materials. For this reason, series of tests involving Scanning Electron Microscopy, Raman Spectroscopy, X-ray diffraction and nanoindentation have been performed on the virgin samples of two types of nuclear graphite’s: IG-110 and nuclear graphite used in decommissioned EWA reactor. Obtained results clearly shows differences in microstructural and mechanical properties of both types of graphite’s. Reported changes have been discusses and attributed to the density of the material and its origin.

Ferritic-martensitic steels are among the prime candidates to make up structural parts of new generation reactors. Nanoindentation was conducted on 2 materials: low activation Fe-9Cr-1WVTa (Eurofer97) and a model pure iron. Both materials were implanted at low energy (275 keV) with Fe ions at different temperatures (roomtemperature, 300 °C, 450 °C), with damage levels ranging from 0.1 to 10 dpa. After implantation, the samples were indented with a diamond Berkovitch tip at room-temperature. The results display varying softening and hardening effects depending on damage level and implantation temperature, which have been correlated with: (i) dislocation loop type distribution, (ii) Cr-content and (iii) the presence of other alloying elements. Obtained mechanical and structural results were compared with the available data from the literature

The long-term exposure of the cable insulation, which are very often manufactured from polymers, to the standard operational environment conditions in nuclear power plant (NPP), such as radiation, heat and humidity, can cause ageing and degradation of their functional properties. Polymers exposed to such factors as ionizing and gamma radiation, undergo significant structural and functional modifications. In order to simulate NPP conditions, one can perform ion irradiation with different irradiation fluences to test insulation of the materials and determine their resistance to radiation. It is known that the main effect of radiation is hydrogen release from polymer. This phenomenon leads to the increase of hardness, shrinkage of the material and deterioration of material resistivity. Polymer materials exposed to ionizing radiation become fragile, stiff, prone to fracture and breaking. In the case of cable insulation, one of the most significant problem is the decrease of their electrical resistance. In this study, structural properties of pristine and irradiated polymer insulation were assessed by Scanning Electron Microscopy (SEM), Raman spectroscopy and resistance measurements. The phase composition was identified by Raman spectroscopy technique. It has been found out that these properties are strongly related to the ion irradiation and structure of the material. Reported findings points to the observation that current-voltage (I-V) characteristics depend from ion irradiation fluence – and material resistivity gradually decreases with the increasing fluence of ions.

International audience; The main purpose of this paper is to summarize our results obtained during research on the radiation behavior of oxides. The paper presents various methods of damage accumulation in irradiated oxides with the special emphasis on correlations between channeling, luminescence and Raman spectroscopy measurements as well as the possibility to obtain quantitative data on polycrystalline materials. The results are interpreted in terms of Multi Step Damage Accumulation model. Without pretending to give a full review of the current trends concerning these studies, we intend to present both a reflection about recent results and a few options for next investigations. This article can thus be regarded as the opening of a discussion on further directions of the research to be conducted on the topic of radiation damage formation in advanced materials for nuclear applications.

In the version of this Article originally published, and in the associated Publisher Correction, the members of the W7-X Team were not included. All versions of the Article, and the Publisher Correction, have now been amended to include these team members.

The experimental knowledge on interlayer potential of graphitic materials is summarized and compared with the computational results based on phenomenological models. Besides Lennard–Jones approximation, the Mie potential is discussed, as well as the Kolmogorov–Crespy model and equation of Lebedeva et al. An agreement is found between a set of reported physical properties of graphite (layer binding energies, compressibility along c-axis in a broad pressure range, Raman frequencies for bulk shear and breathing modes under pressure), when a proper choice of model parameters is taken. It is argued that anisotropic potentials, Kolmogorov–Crespy and Lebedeva, are preferable for modeling, as they provide a better, self-consistent description. A method of fast numerical modeling, convenient for the accurate estimation of the discussed physical properties, is proposed. It may be useful in studies of other van der Waals homo/heterostructures as well.

The problem of information about damage build-up, intensively studied for single crystals, poses many difficulties for polycrystalline materials. The Rutherford Backscattering/Channeling (RBS/C) technique could be applied for single crystals only, but its use is excluded in polycrystalline materials. Therefore the development of a quantitative method well suited for the evaluation of damage level in polycrystalline materials is a must, and still constitutes a major challenge in materials analysis. A comparative study of damage accumulation in magnesium aluminate spinel (MgAl2O4) has been conducted using ionoluminescence (IL) and RBS/C techniques. The results obtained by both methods, demonstrate a two-step character of damage build-up process. The values of the cross-section on the damage creation in each case were estimated using MSDA model. The results presented here confirm the huge potential of the luminescence techniques for damage analysis in single- and polycrystalline samples, and ability of the IL method to perform fast, in situ analysis of damage accumulation process.

International audience; The micro-structural modifications produced in MgO single crystals exposed to medium-energy heavy ions (1.2-MeV Au) were investigated using Rutherford backscattering spectrometry in channeling geometry coupled to Monte-Carlo analyses, secondary ion mass spectrometry, X-ray diffraction and transmission electron microscopy. The damage accumulation and the elastic strain variation were interpreted in the framework of the multi-step damage accumulation (MSDA) model. Both build-ups follow a multi-step process similar to that recently observed for ion-irradiated yttria-stabilized zirconia (YSZ) single crystals. However, in MgO, an unexpectedly high disorder level occurs far beyond the theoretical damage distribution. These results strongly suggest that the migration of defects created in the near-surface layer is most likely at the origin of the broadening of the damage depth distribution in MgO.

The results of studies on preparation of gadolinium zirconate pyrochlore ceramics are presented. Gd 2 Zr 2 O 7 powders were prepared by repeated annealing and milling runs of commercial ZrO 2 and Gd 2 O 3 micro- and nanopowders and hot-pressed at 1450 °C. Scanning Electron Microscopy (SEM) analysis of the microstructure shows average grain size to vary from 1.0 to 5.9 µm depending on a type of used mixtures. Sintered ceramics were characterized by X-ray diffraction. The highest intensity of the pyrochlore superstructure peaks was found for ceramics obtained from the mixture of nanopowders. The ratio of intensity of the strongest pyrochlore line to the intensity of the strongest peak characteristic for both structures (fluorite and pyrochlore) equals to 4.5% indicating about 80% pyrochlore ordering.

A semi-thick target method has been used to measure the stopping power for recoils produced in the 120 Sn( 14 N, 5n) 129 La, 120 Sn( 11 B, 4n) 127 Cs and 118 Sn( 11 B, 4n) 125 Cs reactions by γ-ray lineshape analysis. The target quality and thickness (1.2 mg/cm 2 ) were determined by the Rutherford backscattering spectrometry technique. Electronic and nuclear stopping-power parameters were determined for Cs and La ions in Sn and compared with parameters measured with the same method for Pm, Sm and Nd ions in Cd and I ions in Ag. A comparison with the LSS theory was made for the energy range below 0.2 MeV/nucleon, where the Bethe–Bloch formula has no application.

The zirconium–zirconia interface that developed during high-temperature corrosion of pure zirconium was investigated. Samples were oxidized at 600 °C in air at atmospheric pressure. The oxidized sample was then prepared by means of focused ion beam (FIB) lift-out technique and examined using Raman spectroscopy technique in three different oxide zones (external, internal, and close to the metal–oxide interface). Structural investigation was performed using line mode Raman analysis. Implementation of these techniques revealed complexity of the studied system and confirmed the presence of a thin tetragonal sub-layer located in the proximity of the metal. Recorded Raman band displacements of monoclinic and tetragonal phases were interpreted in terms of stoichiometry level and compressive stress in the oxide. The thin layer of tetragonal phase is most likely characterized by lower amount of oxygen than the external part of the oxide.

The modifications of the microstructure of yttria-stabilized cubic zirconia and silicon carbide single crystals implanted with high concentrations of noble gas ions and subsequently annealed at high temperature were characterized using RBS/C, XRD and TEM. It is found that the annealing behavior is strongly dependent on both the material and the implanted noble gases. Ar-implanted yttria-stabilized zirconia shows no significant microstructural modification upon annealing at 800 °C, e.g. dislocations are still present and the size of the Ar bubbles does not evolve. This is in strong contrast with previous observations on helium-implanted zirconia, where the formation of bubbles and elongated fractures were observed. In the case of SiC, thermal annealing at 1000 °C shows an enhanced damage recovery when He is implanted as compared to Ar implantation and the recrystallization of the matrix is accompanied with the release of noble gas atoms. This difference can be ascribed to different atomic radii, and thus mobility of implanted species.

In the paper effects of surfacemodification of various elastomers upon irradiationwithH+, He+, F+ or Ar+ ions are presented. Changes to chemical composition and physical structure of rubber macromolecules are discussed in terms of influence of the treatment onmodification of surface layer of the elastomers. Hydrogen release induced graphitization together with post-treatment oxidation of rubber macromolecules increase surfacewettability of thematerials, facilitating lowering of „wet” friction. Free radicals being created due to interactions between energetic ions and macromolecules produce additional crosslinking, which manifests itself by increased hardness of the elastomers. Modification of mechanical properties of the surface layer changes mechanism of elastomer friction from the bulk to the surface one, what results in significant reduction of friction. Despite crosslinking induced shrinkage of the surface layer, which results in its micro-cracking, ion beam treated elastomers showed to bewear resistant due to the lack of delamination under stress. Interesting results were obtained for heavy Ar+ ions surface etched butadiene-acrylonitrile rubber/multiwalled carbon nanotube (NBR/MWCNT) composites. Nanotube agglomerates created from rubber substrate resulted in „island” morphology, significantly reducing friction of the material.