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Tungsten (W), as a promising plasma-facing material for fusion nuclear reactors, exhibits ductility reduction. Introducing high-density coherent nano-dispersoids into the W matrix is a highly efficient strategy to break the tradeoff of the strength–ductility performance. In this work, we performed helium (He) ion irradiation on coherent oxide-dispersoids strengthened (ODS) W to investigate the effect of coherent nanoparticle interfaces on the behavior of He bubbles. The results show that the diameter and density of He bubbles in ODS W are close to that in W at low dose of He ion irradiation. The radiation-induced hardening increment of ODS W, being 25% lower than that of pure W, suggests the involvement of the coherent interface in weakening He ion irradiation-induced hardening and emphasizes the potential of coherent nano-dispersoids in enhancing the radiation resistance of W-based materials.

Magnetic sensors are key elements in many industrial, security, military, and biomedical applications. Heusler alloys are promising materials for magnetic sensor applications due to their high spin polarization and tunable magnetic properties. The dynamic field range of magnetic sensors is strongly related to the perpendicular magnetic anisotropy (PMA). By tuning the PMA, it is possible to modify the sensing direction, sensitivity and even the accuracy of the magnetic sensors. Here, we report the tuning of PMA in a Co2MnGa Heusler alloy film via argon (Ar) ion irradiation. MgO/Co2MnGa/Pd films with an initial PMA were irradiated with 30 keV 40Ar+ ions with fluences (ions·cm−2) between 1 × 1013 and 1 × 1015 Ar·cm−2, which corresponds to displacement per atom values between 0.17 and 17, estimated from Monte-Carlo-based simulations. The magneto optical and magnetization results showed that the effective anisotropy energy (Keff) decreased from ~153 kJ·m−3 for the un-irradiated film to ~14 kJ·m−3 for the 1 × 1014 Ar·cm−2 irradiated film. The reduced Keff and PMA are attributed to ion-irradiation-induced interface intermixing that decreased the interfacial anisotropy. These results demonstrate that ion irradiation is a promising technique for shaping the PMA of Co2MnGa Heusler alloy for magnetic sensor applications.

A wide electrochemical window makes boron-doped diamond (BDD) a promising electrode material. To utilize its excellent properties, nanopore formation on the surface to increase the specific surface area is highly desirable. Although anodization has the potential to produce nanoporous structures on the surface of materials, BDD has yet to be anodized due to its high physical and chemical stability. Here, we report that high-energy Si(II) ion irradiation forms sp2 defects, which enable the anodization of BDD, and demonstrate that this anodization results in the formation of nanoporous BDD.

In the current work, an analysis of the effects of Y on the radiation hardening and microstructure response of a V-4Cr-4Ti alloy has been conducted after 30 keV D ion irradiation at room temperature using transmission electron microscopy (TEM) and nanoindentation. The results show that the formation of large Y2O3 and small Y2V2O7 nanoparticles was confirmed, indicating that the addition of Y reduces the amount of dissolved oxygen. The addition of Y has been shown to affect the radiation-induced dislocation loops, radiation hardening, and Ti-rich segregation of the V-4Cr-4Ti alloy. With the addition of Y, the mean size of the radiation-induced dislocation loop decreased, which may result from the strong sink strength of the nanoparticle/matrix interface, interactions between Y atoms and SIA clusters, and the strong binding energy of vacancy–oxygen pairs. Some particles with core–shell structures were observed after ion irradiation, where Ti-rich segregations at the nanoparticle/matrix interface were confirmed. These results indicate that Y might promote abnormal segregation. Possible causes for this include the lower interface energy at the particle/matrix interface and the interaction between oxygen and solute atoms.

Zr/Nb nanoscale multilayers are regarded as one of the important candidate materials used in next-generation reactors. Understanding structural evolution induced by ion bombardment is crucial for the evaluation of lifetime performance. Magnetron sputter-deposited Zr/Nb multilayers with a periodicity of 7 nm were subjected to 300 keV He ion irradiation with three different fluences at room temperature. The depth-resolved strain and damage profiles in the Zr/Nb multilayers were investigated by grazing incidence X-ray diffraction. The tensile strain was found in the deposited Zr/Nb films. After He ion irradiation, the intensity of diffraction peaks increased. The change in diffraction peaks depends on He fluence and incident angle. Irradiation-induced pre-existing defect annealing was observed and the ability to recover the microstructure was more significant in the Zr films compared to the Nb films. Furthermore, the efficiency of defect annealing depends on the concentration of pre-existing defects and He fluence. When the He fluence exceeds the one for pre-existing defect annealing, residual defects will be formed, such as 1/3 and 1/3 dislocation loops in the Zr films and 1/2 dislocation loops in the Nb films. Finally, introducing deposited defects and interfaces can improve the radiation resistance of Zr/Nb nanoscale multilayers. These findings can be extended to other multilayers in order to develop candidate materials for fusion and fission systems with high radiation resistance.

In this work, nanocomposite samples of polyaniline (PANI) and lead sulfide nanoparticles (PbSNPs) were prepared, utilizing the solution preparation method, for implantation in energy storage elements. The PANI/PbS films were irradiated by different fluences of oxygen beam: 5 × 1016, 10 × 1016, and 15 × 1016 ions.cm−2. The composite was investigated by XRD, SEM, DSC, and FTIR. After ion irradiation, the Tg and Tm values decreased by 4.8 °C and 10.1 °C, respectively. The conductivities, electrical impedances, and electrical moduli of untreated and irradiated samples were examined in frequencies ranging from 102 Hz to 5 MHz. Moreover, the ion beam caused a modification in the dielectric characteristics of PANI/PbS. The dielectric constant ε′ was improved from 31 to 611, and the electrical conductivity increased from 1.45 × 10−3 S/cm to 25.9 × 10−3 S/cm by enhancing the fluence to 15 × 1016 ions.cm−2. Additionally, the potential energy barrier, Wm, decreased from 0.43 eV to 0.23 eV. The induced changes in the dielectric properties and structural characteristics of the PANI/PbS samples were determined. These modifications provide an opportunity to use irradiated PANI/PbS samples for several applications, including microelectronics, batteries, and storage of electrical energy.

We studied by means of an atomistic model based on molecular dynamics the thermal evolution of surface atoms in amorphous silica under high electronic excitation produced by irradiation with swift heavy ions. The model was validated with the total and differential yields measured in sputtering experiments with different ions and ion energies showing a very good quantitative prediction capability. Three mechanisms are behind the evolution of the surface region: (1) an ejection mechanism of atoms and clusters with kinetic energy exceeding their binding energy to the sample surface, which explains the experimentally observed angular distributions of emitted atoms, and the correlation of the total sputtering yield with the electronic stopping power and the incidence angle. (2) A collective mechanism of the atoms in the ion track originated by the initial atom motion outwards the track region subsequently followed by the return to the resulting low-density region in the track center. The collective mechanism describes the energy dissipation of bulk atoms and the changes in density, residual stress, defect formation and optical properties. (3) A flow mechanism resulting from the accumulation and subsequent evolution of surface atoms unable to escape. This mechanism is responsible for the crater rim formation. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was funded by the projects Radiafus-5 (PID2019-105325RB-C32) of Spanish Ministry of Science, Technofusion (S2018/EMT-4437) of Madrid Regional Government and Eurofusion (EH150531176). The authors acknowledge the computer resources and technical assistance provided by the Centro de Supercomputación y Visualización de Madrid (CeSViMa) CESVIMA-MAGERIT. AP acknowledges the support of FONDECYT under grants 3190123. EMB thanks support from grant ANPCyT PICTO-UUMM-2019-00048. JK was supported by the Beatriz Galindo Program (BEAGAL18/00130) from the Ministerio de Educación y Formación Profesional of Spain.

The Dual-beam ion irradiation facility for Fusion materials (DiFU) has been developed and installed at the Ruđer Bošković Institute with the purpose to perform irradiation of samples of fusion materials by one or two ion beams. Ion beams are delivered to the DiFU chamber by a 6 MV EN Tandem Van de Graaff and a 1 MV HVE Tandetron accelerator, enabling irradiation of areas up to 30 × 30 mm2. The sample holder enables the three-dimensional positioning of samples that can be irradiated while being heated, cooled, or kept at room temperature. Ion fluxes are measured indirectly by the insertion of two large Faraday cups. Besides, the ion flux is monitored continuously by two sets of horizontal and vertical slits, which, in turn, define the limits of the irradiation area on the sample. Sample temperature and conditions during irradiation are additionally monitored by a set of thermocouples, an IR camera, and a video camera. Particular care is dedicated to the mitigation of carbon contamination during ion irradiation.

Laser plasma acceleration has made remarkable progress in the last few decades, but it also faces many challenges. Although the high gradient is a great potential advantage, the beam quality of the laser accelerator has a certain gap, or it is different from that of traditional accelerators. Therefore, it is important to explore and utilize its own features. In this article, some recent research progress on laser proton acceleration and its irradiation application, which was carried out on the compact laser plasma accelerator (CLAPA) platform at Peking University, have been introduced. By combining a TW laser accelerator and a monoenergetic beamline, proton beams with energies of less than 10 MeV, an energy spread of less than 1%, and with several to tens of pC charge, have been stably produced and transported in CLAPA. The beamline is an object–image point analyzing system, which ensures the transmission efficiency and the energy selection accuracy for proton beams with large initial divergence angle and energy spread. A spread-out Bragg peak (SOBP) is produced with high precision beam control, which preliminarily proved the feasibility of the laser accelerator for radiotherapy. Some application experiments based on laser-accelerated proton beams have also been carried out, such as proton radiograph, preparation of graphene on SiC, ultra-high dose FLASH radiation of cancer cells, and ion-beam trace probes for plasma diagnosis. The above applications take advantage of the unique characteristics of laser-driven protons, such as a micron scale point source, an ultra-short pulse duration, a wide energy spectrum, etc. A new laser-driven proton therapy facility (CLAPA II) is being designed and is under construction at Peking University. The 100 MeV proton beams will be produced via laser–plasma interaction by using a 2-PW laser, which may promote the real-world applications of laser accelerators in malignant tumor treatment soon.

The variation of transport behaviour in a mesoscopic Fe60Al40 wire, initially possessing the ordered B2-phase structure, has been observed while inducing a phase transition to the disordered A2 structure. Gradual disordering was achieved using a highly focused beam of Ne+-ions. Both electrical resistance and anomalous Hall effect were measured in parallel with the local ion irradiation. Both the normal and Hall resistivity show a peak as a function of fluence. Moreover, the relationship between Hall resistivity and normal resistivity reconfirms the presence of two distinct regimes in the transition. Furthermore, field-dependence and temperature-dependence measurements were used to identify that it is necessary to consider the effect of scattering from magnetic clusters to understand these different regimes in transport properties.

EBSD data and irradiation parameters

We studied the influence of Ag15+ (200 MeV) ion irradiation on the surface electronic structure of an epitaxial LaNiO3 films on a (100) oriented LaAlO3 substrate, using surface sensitive La (4d to 4f) and Ni (3p to 3d) photoemission transitions in the pristine, highest (1012 ions/cm2), medium (5 × 1011 ions/cm2), and lowest (1011 ions/cm2) ion-doses of irradiation. The Super-Coster Kronig induced slight enhancement in the spectral features around ∼115–116 eV photon energy for La (4d to 4f) transitions were observed, with absence of such enhancement for Ni (3p to 3d) transitions in the pristine and irradiated samples. Moreover, an alteration in the constant initial state (CIS) spectra for La (4d to 4f) transitions and presence of a surface states close to the Fermi level in the valence band spectra for Ni (3p to 3d) transitions, with a different ion-doses found to be associated with the oxygen vacancies. Interestingly for Ni (3p to 3d) transition spectra, the density of states (DOS) at the Fermi Level was found to increase orderly with the irradiation dose, and a systematic correlation between the DOS at Fermi level and the surface states was found in the pristine and irradiated samples. For the highest dose sample, the surface states lie above the Fermi level has highest DOS at the Fermi level, which is due to upward shift of the surface states towards the Fermi level with an increase in the irradiation dose., This project has received funding from EU-H2020 research and innovation program under grant agreement No. 654360 within NFFA- Europe transnational access activity. We thanks Inter-University Accelerator center (IUAC), New Delhi, India, for providing access to ion- irradiation facility under duly approved projects IUAC/XIII.7/UFR-62333 and IUAC/XIII.3A/64207/MS (BTR-2). We also thanks Raja Ramanna center for Advanced Technology (RRCAT), Indore (India) for providing access to valence band spectroscopy measurements at INDUS-1. Vishal Sharma expresses his gratitude to Panjab University, Chandigarh (1019–40/Estt.-I dated 16/02/2017) and thereafter UGC-DAE CSR Indore (CSR-IC/BL-09/CRS-106/2019–20/202) for providing fellowship for carrying out research work. Ms. Sunidhi expresses her thanks to UGC, New Delhi for providing fellowship for research work. F. Sánchez acknowledges financial support from the Spanish Ministry of Science and Innovation, through the Severo Ochoa FUNFUTURE (CEX2019–000917-SMCIN AEI/10.13039/501100011033) and PID2020112548RB (MCIN/AEI/ 0.13039 /5011 000110 33)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Molybdenum disulfide (MoS2) is considered promising noble metal-free catalysts for the hydrogen evolution reaction (HER). Whereas the bulk MoS2 does not exhibit significant activity, the catalytic properties of various nanostructures are noticeable. Therefore we synthesized flower-like molybdenum disulfide with the simple, one-step hydrothermal method. To enhance the catalytic activity of the material, low-energy ion irradiation is employed. As-prepared MoS2 is irradiated with hydrogen and carbon ions of various energies (20–40 keV) and fluences (1014-1017 ion/cm2). Our results show that irradiation has beneficial influence on MoS2 catalytic activity toward hydrogen evolution reaction. By producing morphological changes and defects in the structure, ion irradiation also impacts the conductivity of the material, which shows predominant effect on hydrogen evolution. The increase of current density at an overpotential of 300 mV with hydrogen ion irradiation is even 6 times higher than for as-synthesized catalyst.

The investigation is focused on the simulation of the I-V characteristics of Si p+-n-n+ diodes irradiated with medium-energy 40Ar ions whose range is less than the detector thickness. The characteristics were simulated by considering the distribution of the current generating defects related to the profile of primary vacancies with a sharply rising density at the end of the ion track, which was defined by using the TRIM software. The defects involved in the simulation were two radiation-induced acceptors, the one positioned at EC - 0.42 eV and the other in the lower half of the bandgap at EC – 0.65 eV, responsible for the bulk current generation and the electric field distribution, respectively. With the adjusted characteristics of the defects, I-V characteristics in the fluence range (1-4)×109 cm-2 demonstrated a quantitative agreement with the experimental curves and a strict proportionality of the maximum current to the fluence. The electric field evolution with ion fluence was calculated and discussed as information complementary to the I-V data., Работа посвящена моделированию генерационного тока кремниевых детекторов, облученных ионами 40Ar средней энергией, формирующих в структуре пик Брэгга. Продемонстрированы моделирование распределения первичных дефектов в среде TRIM, распределения электрического поля при различных дозах облучения, а также сравнение экспериментальных вольт-амперных характеристик и построенных на основе моделирования. В качестве основы для расчетов принята двухуровневая модель генерации тока.

4H-SiC based p-n junction UV photo-detectors were irradiated with 600 keV He+ in the fluence range of 5 × 1011 ÷ 5 × 1014 ion/cm2 in order to investigate their radiation hardness. The effects of irradiation on the electro-optical performance were monitored in dark condition and in the UV (200 ÷ 400 nm) range, as well as in the visible region confirming the typical visible blindness of unirradiated and irradiated SiC photo-sensors. A decrease of UV optical responsivity occurred after irradiation and two fluence regimes were identified. At low fluence (13 ions/cm2), a considerable reduction of optical responsivity (of about 50%) was measured despite the absence of relevant dark current changes. The presence of irradiation induced point defects and then the reduction of photo-generated charge lifetime are responsible for a reduction of the charge collection efficiency and then of the relevant optical response reduction: point defects act as recombination centers for the photo-generated charges, which recombine during the drift/diffusion toward the electrodes. At higher irradiation fluence, the optical responsivity is strongly reduced due to the formation of complex defects. The threshold between low and high fluence is about 100 kGy, confirming the radiation hardness of SiC photo-sensors.

In this work, a comparative study of surface morphology and elemental distribution of thin films of the M:In:C (with M = Sc or Zr) ternary composites irradiated with 2 MeV W+ ions with fluences 101...

In this work, a new hardening model is proposed for the depth-dependent hardness of ion-irradiated polycrystals with obvious grain size effect. Dominant hardening mechanisms are addressed in the model, including the contribution of dislocations, irradiation-induced defects and grain boundaries. Two versions of the hardening model are compared, including the linear and square superposition models. A succinct parameter calibration method is modified to parametrize the models based on experimentally obtained hardness vs. indentation depth curves. It is noticed that both models can well characterize the experimental data of unirradiated polycrystals; whereas, the square superposition model performs better for ion-irradiated materials, therefore, the square superposition model is recommended. In addition, the new model separates the grain size effect from the dislocation hardening contribution, which makes the physical meaning of fitted parameters more rational when compared with existing hardness analysis models.

One of the main complications for the interpretation of reflectance spectra of airless planetary bodies is surface alteration by space weathering caused by irradiation by solar wind and micrometeoroid particles. We aim to evaluate the damage to the samples from H and laser irradiation and relate it to the observed alteration in the spectra. We used olivine (OL) and pyroxene (OPX) pellets irradiated by 5 keV H ions and individual fs laser pulses and measured their visible (VIS) and near-infrared (NIR) spectra. We observed the pellets with scanning and transmission electron microscopy. We studied structural, mineralogical, and chemical modifications in the samples and connected them to changes in the reflectance spectra. In both minerals, H irradiation induces partially amorphous sub-surface layers containing small vesicles. In OL pellets, these vesicles are more tightly packed than in OPX ones. Related spectral change is mainly in the VIS spectral slope. Changes due to laser irradiation are mostly dependent on material's melting temperature. Only the laser-irradiated OL contains nanophase Fe particles, which induce detectable spectral slope change throughout the measured spectral range. Our results suggest that spectral changes at VIS-NIR wavelengths are mainly dependent on thickness of (partially) amorphous sub-surface layers. Amorphisation smooths microroughness, increasing the contribution of volume scattering and absorption over surface scattering. Soon after exposure to the space environment, the appearance of partially amorphous sub-surface layers results in rapid changes in the VIS spectral slope. In later stages (onset of micrometeoroid bombardment), we expect an emergence of nanoparticles to also mildly affect the NIR spectral slope. An increase in dimensions of amorphous layers and vesicles in the more space-weathered material will only cause band-depth variation and darkening., Comment: 9 pages, 8 figures, 1 table. Abstract was modified to comply with the required maximum number of characters of arXiv abstracts

Tailoring the blue photoluminescence (PL) in Al-doped ZnO (AZO)/TiO2 heterostructures is demonstrated by a controlled induction of shallow defect centers by 50 keV Ar+-ions. This is established by a combination of temperature dependent PL and electron paramagnetic resonance spectroscopy. The dominant blue-violet PL in an as-grown sample comprises a near band-edge emission, along with a peak associated with a radiative recombination of the electrons in shallow donor levels (Zn interstitials) and the holes from the valence band. However, the evolution of an additional yellow-green PL band at a fluence of 1 × 1015 ions/cm2 is governed by deep donor levels, particularly ionized oxygen vacancies. Irradiation at 1 × 1016 ions/cm2 further leads to the formation of Zn vacancies (shallow acceptors) owing to the development of an O-rich surface. The structural modifications of these samples have been investigated by field-emission scanning electron microscopy , transmission electron microscopy, and Rutherford backscattering. While small micro-cracks are found at a fluence of 2 × 1016 ions/cm2, the formation of graded layers is obtained at the highest fluence of 5 × 1016 ions/cm2 owing to ballistic intermixing and diffusion of the constituents. Detailed investigation suggests that a significant amount of Ti atoms is diffused in AZO by a complete deterioration of the AZO/TiO2 matrix at the highest fluence.

Replacement of conventional Zircaloy fuel cladding with silicon carbide (SiC) fuel cladding is expected to significantly decrease the amount of hydrogen generated from fuel claddings by the reaction with steam during severe accidents. One of their critical issues addressed regarding practical application has been hydrothermal corrosion. Thus, the corrosion resistant coating technology using a Ti-Cr multilayer was developed to suppress silica dissolution from SiC fuel cladding into reactor coolant under normal operation. The effect of radiation on adhesion of the coating to SiC substrate and its microstructure characteristics were investigated following Si ion irradiation at 573 K up to 3 dpa for SiC. Measurement of swelling in pure Ti, pure Cr and SiC revealed that the maximum inner stress attributed to the swelling difference was generated between the coating and SiC substrate by irradiation of 1 dpa. No delamination and cracking were observed in cross-sectional specimens of the coated SiC irradiated up to 3 dpa. According to analyses using transmission electron microscopy, large void formation and cascade mixing due to irradiation were not observed in the coating. The swelling in the coating at 573 K was presumed to be caused by another mechanism during radiation such as point defects rather than void formation.

International audience; •The coupled influence of the intense electronic and nuclear energy deposition on the defect production were investigated in UO2.•The evolution of local disorder (evaluated by Raman) and the stress level (determined by XRD) on fluorite-type oxides ceramics under the effect of intense electronic excitation was followed.•A possible synergetic effect between the pre-existing defects and those generated by intense electronic ionizations was revealed. The coupled effects of nuclear and electronic energy losses were investigated in uranium dioxide (UO2). Single and sequential ion irradiations were carried out with 92 MeV Xe ions and 0.9 MeV I ions. Raman spectroscopy and X-ray diffraction analyses were combined with the inelastic thermal spike (iTS) model to investigate the effect of electronic ionizations on the ballistic damage. It appears that the high-energy ions induce a significant change in the defect distribution with an amplitude that depends on the level of pre-existing disorder. This modification essentially results in an acceleration of the transformation from the dislocation loops to the dislocation lines, a process that is accompanied by a stress relaxation. Surprisingly, with the fluence increase of 92 MeV Xe ions, the stress starts to increase again, highlighting a possible synergetic effect between the pre-existing defects and those generated by the 92 MeV Xe ions irradiation.

Severe plastic deformation has proven to be a promising method for the in situ manufacturing of metal-matrix composites with improved properties. Recent investigations have revealed a severe mixing of elements, as well as the formation of non-equilibrium intermetallic phases, which are known to affect physical and mechanical properties. In this work, a multilayered aluminum–magnesium (Al-Mg) nanostructured composite was fabricated using constrained high-pressure torsion (HPT) in a Bridgeman-anvil-type unit. A microstructure investigation and X-ray diffraction analysis allowed us to identify the presence of intermetallic Al3Mg2 and Al12Mg17 phases in the deformed nanostructured composite. The sputtering yield of the Al3Mg2 and Al12Mg17 phases was found to be 2.2 atom/ion and 1.9 at/ion, respectively, which is lower than that of Mg (2.6 at/ion). According to density functional theory (DFT)-based calculations, this is due to the higher surface-binding energy of the intermetallic phases (3.90–4.02 eV with the Al atom removed and 1.53–1.71 eV with the Mg atom removed) compared with pure Al (3.40–3.84 eV) and Mg (1.56–1.57 eV). In addition, DFT calculations were utilized to calculate the work functions (WFs) of pure Al and Mg and the intermetallic Al3Mg2 and Al12Mg17 phases. The WF of the obtained Al-Mg nanostructured composite was found to be 4 eV, which is between the WF value of Al (4.3 eV) and Mg (3.6 eV). The WF of the Al12Mg17 phase was found to be in a range of 3.63–3.75 eV. These results are in close agreement with the experimentally measured WF of the metal matrix composite (MMC). Therefore, an intermetallic alloy based on Al12Mg17 is proposed as a promising cathode material for various gas-discharge devices, while an intermetallic alloy based on Al3Mg2 is suggested as a promising optical- and acoustic-absorbing material.

In this study, the impact of low-energy (1 keV) Ar+ ion-beam irradiation on the morphology of polycrystalline Ti disks was investigated. Targets were prepared by cutting and mechanically polishing commercial rods. The surface topographies before and after irradiation were characterized by scanning electron microscopy (SEM) and mechanical profilometry. Irradiation was performed using a wide range of incident angles (αi) from normal to grazing geometries at a total dose of 1018 ions/cm2. SEM analysis of the irradiated Ti targets revealed clear texturing with various attainable surface morphologies depending on αi. The surface features varied from ripples within patches with fingerprint-like patterns (0 ≤ αi ≤ 60°) to oriented structures parallel to the direction of the ion beam, such as pillar/tip structures (65 ≤ αi ≤ 75°) and shallow ripples (αi ≈ 80°). This morphological selectivity could be attributed to the competitive diffusive and erosive regimes, where the lateral uniformity of the morphology was affected by the limited size of the crystal grains. Finally, the wettability and biocompatibility of the characteristic topographies were evaluated, and the results indicated improved performance of the ion-beam-textured surfaces compared to the untreated ones. This research was financially supported by Dirección General de Asuntos del Personal Académico (DGAPA) from Universidad Nacional Autónoma de México (UNAM) under grant PAPIIT IN-114120, by Ministerio de Ciencia, Innovación y Universidades (Spain), Agencia Estatal de Investigación (AEI, Spain), and Fondo Europeo de Desarrollo Regional (FEDER, EU) through grants PGC2018-094763-B-I00, PID2021-123969NB-I00, and by Comunidad de Madrid (Spain) under the Multiannual Agreement with UC3M for Excellence of University Professors (EPUC3M23), in the context of the “V Plan Regional de Investigación Científica e Innovación Tecnológica” (PRICIT). Additional funding was obtained from Consejo Nacional de Ciencia y Tecnología (CONACyT, Mexico) under “Estancias Posdoctorales en el Extranjero Vinculadas a la Consolidación de Grupos de Investigación y Fortalecimiento del Posgrado Nacional” with scholarship numbers 711146, and 740556. Publicado

Abstract The capability to structure two-dimensional materials (2DMs) at the nanoscale with customizable patterns and over large areas is critical for a number of emerging applications, from nanoelectronics to 2D photonic metasurfaces. However, current technologies, such as photo- and electron-beam lithography, often employing masking layers, can significantly contaminate the materials. Large-area chemical vapour deposition-grown graphene is known to have non-ideal properties already due to surface contamination resulting from the transferring process. Additional contamination through the lithographic process might thus reduce the performance of any device based on the structured graphene. Here, we demonstrate a contactless chemical-free approach for simultaneous patterning and cleaning of self-supporting graphene membranes in a single step. Using energetic ions passing through a suspended mask with pre-defined nanopatterns, we deterministically structure graphene with demonstrated feature size of 15 nm, approaching the performance of small-area focused ion beam techniques and extreme ultraviolet lithography. Our approach, however, requires only a broad beam, no nanoscale beam positioning and enables large area patterning of 2DMs. Simultaneously, in regions surrounding the exposed areas, contaminations commonly observed on as-grown graphene targets, are effectively removed. This cleaning mechanism is attributed to coupling of surface diffusion and sputtering effects of adsorbed surface contaminants. For applications using 2DMs, this simultaneous patterning and cleaning mechanism may become essential for preparing the nanostructured materials with improved cleanliness and hence, quality.

The 316L stainless steels (SS) have become one of the most common structural materials in nuclear system applications due to their excellent physicochemical performance. Selective laser melting (SLM) preparation, mechanical properties, and irradiation resistance of 316L SS reinforced by second-phase particles have aroused extensive attention. Here, the mechanical properties of 316L SS with different LaB6 contents processed by SLM before irradiation and the irradiation-induced swelling after 50 keV He+ irradiation at room temperature were investigated. Results showed that the microstructure was refined with the LaB6 addition, and the size of 316L SS subgrains decreased with the increase of LaB6. LaB6 reinforced 316L SS (316L-LaB6) exhibited higher hardness and yield strength compared with 316L SS without LaB6 addition. After 50 keV He+ irradiation, the irradiation-induced swelling rate of 316L-LaB6 was lower than that of 316L SS without LaB6 addition, indicating that LaB6 improved the irradiation resistance of 316L SS. Consequently, our study indicated the potential of using 316L-LaB6 as irradiation-resistant material.

Carbon exhibits a remarkable range of structural forms, due to the availability of sp3, sp2 and sp1 chemical bonds. Contrarily to other group IV elements such as silicon and germanium, the formation of an amorphous phase based exclusively on sp3 bonds is extremely challenging due to the strongly favored formation of graphitic-like structures at room temperature and pressure. As such, the formation of a fully sp3-bonded carbon phase requires an extremely careful (and largely unexplored) definition of the pressure and temperature across the phase diagram. Here, we report on the possibility of creating full-sp3 amorphous nanostructures within the bulk crystal of diamond with room-temperature ion-beam irradiation, followed by an annealing process that does not involve the application of any external mechanical pressure. As confirmed by numerical simulations, the (previously unreported) radiation-damage-induced formation of an amorphous sp2-free phase in diamond is determined by the buildup of extremely high internal stresses from the surrounding lattice, which (in the case of nanometer-scale regions) fully prevent the graphitization process. Besides the relevance of understanding the formation of exotic carbon phases, the use of focused/collimated ion beams discloses appealing perspectives for the direct fabrication of such nanostructures in complex three-dimensional geometries.

We report 491 new near-infrared spectroscopic measurements of 420 near-Earth objects (NEOs) collected on the NASA InfraRed Telescope Facility (IRTF) as part of the MIT-Hawaii NEO Spectroscopic Survey (MITHNEOS). These measurements were combined with previously published data (Binzel et al. 2019) and bias-corrected to derive the intrinsic compositional distribution of the overall NEO population, as well as of subpopulations coming from various escape routes (ERs) in the asteroid belt and beyond. The resulting distributions reflect well the overall compositional gradient of the asteroid belt, with decreasing fractions of silicate-rich (S- and Q-type) bodies and increasing fractions of carbonaceous (B-, C-, D- and P-type) bodies as a function of increasing ER distance from the Sun. The close compositional match between NEOs and their predicted source populations validates dynamical models used to identify ERs and argues against any strong composition change with size in the asteroid belt between ~5 km down to ~100 m. A notable exception comes from the over-abundance of D-type NEOs from the 5:2J and, to a lesser extend, the 3:1J and nu6 ERs, hinting at the presence of a large population of small D-type asteroids in the main belt. Alternatively, this excess may indicate preferential spectral evolution from D-type surfaces to C- and P-types as a consequence of space weathering, or to the fact that D-type objects fragment more often than other spectral types in the NEO space. No further evidence for the existence of collisional families in the main belt, below the detection limit of current main-belt surveys, was found in this work., 23 pages, 6 figures, accepted for publication in AJ

Using the method of X-ray photoelectron spectroscopy (XPS), a comparative analysis of the structure and chemical state of multi-walled carbon nanotubes doped with nitrogen during their synthesis, as well as by high-dose irradiation with nitrogen ions, is carried out. It is shown that the chemical state of nitrogen in the walls of MWCNTs doped with various methods differs significantly. It was found that the use of ion irradiation allows one to obtain MWСNTs with a higher nitrogen concentration in the structure of the outer walls. However, there is a significant increase in the degree of imperfection of the crystal structure of the walls of carbon nanotubes and the formation of oxygencontaining functional groups. The features of the chemical state of nitrogen in the walls of MWCNTs using various alloying methods are established. The results obtained in this work can be used to develop methods for modifying the electronic structure of carbon nanostructured materials.

In this work, for the first time, fragmentation and joining of tungsten oxide (WO3) nanorods induced by a broad ion beam are reported. Although at low energy (5 keV) and moderate ion fluence, nanorods fragment into smaller pieces along the length, at higher ion energies (50-100 keV), a contrary process occurs, which leads to the joining of the nanorods. A state-of-the-art ion-solid interaction simulation, namely, TRI3DYN, has been invoked to explore the possible mechanisms that reveal subtle contributions of surface defects, ion-beam mixing, and sputtering. High-resolution electron microscopy, photoluminescence study, and X-ray photoelectron spectroscopy support the observed results and proposed mechanisms. Such modifications have interesting effects on the electrical conductivity of the nanorod assembly. The change in sample color upon ion irradiation from initial white to yellow, light blue, deep blue, light green, and cyan shows an excellent and reversible chromatic response of tungsten oxide nanorods to irradiation. Such a property can be exploited to fabricate radiation sensors. The fragmentation and joining at different energy scales have essential implications in nanodevice fabrication through the bottom-up approach as well as for the development of fusion reactors.

The mechanism of the shape elongation of metal nanoparticles (NPs) in silica, which is induced under swift heavy ion irradiation, is discussed with comparing the two candidates: (i) the synergy between the ion hammering and the transient melting of NPs by the inelastic thermal spike and (ii) the thermal pressure and flow model. We show that three experimental results are inconsistent with (i). The latter is supported by two-temperature molecular dynamics simulations, which simulate not only the atomic motions but also the local electron temperatures. A remarkable correlation was observed between the temporal evolution of the silica density around the ion trajectory and that of the aspect ratio of the NP later than similar to 1 ps after the ion impact, while no correlation was observed earlier than similar to 1 ps, even under the assumption of the instantaneous energy deposition.

This article presents the results of gold deposition into pores of SiO $${}_{2}$$ /Si matrices and the modifications of the obtained SiO $${}_{2}$$ (Au)/Si systems by irradiation with argon Ar $${}^{+}$$ ions with an energy of 100 keV with a fluence of $$5\times 10^{14}$$ ion/cm $${}^{2}$$ . The effect of irradiation on changes in the surface topography of SiO $${}_{2}$$ (Au)/Si systems and the signal intensity of surface-enhanced Raman scattering during the detection of the model analyte (methylene blue) have been shown.

Irradiation with swift heavy ions causes the deformation of Ferric nanoparticles in direction of the ion beam. Fe nanoparticles with mean diameter of about 20 nm were prepared by gas flow sputtering and subsequently confined within silica films. Two silica films wherein two different densities of Fe nanoparticles are encapsulated were irradiated with 50 MeV Ag ions with fluences of few 1014 ions.cm−2 at 300 K and normal incidence. Transmission electron microscopy analysis shows that the spherical Fe nanoparticles are deformed into prolate nanorods aligned in direction of the incident ion beam. The depth distribution profiles of irradiated particles reveal the presence of a critical fluence above which the elongation kinetics becomes dependent on the nanoparticles density. Analysis indicates that for the lower density particles, a saturation length is reached under irradiation to fluence between 3–4 × 1014 ions.cm−2. However, for the higher density, collective growth into aligned nanowires is presumed to take place. Hysteresis curves of the saturation magnetization and coercivity indicate an increasing magnetic anisotropy, which can be correlated with the deformation of nanoparticles in the direction of the ion beam.

Mechanical properties of gallium nitride (GaN) single crystals upon carbon ion irradiation are examined using nanoindentation analysis at room temperature. Pop-in events in the load-depth curves are observed for unirradiated and irradiated GaN samples. A statistical linear relationship between the critical indentation load for the occurrence of the pop-in event and the associated displacement jump is exhibited. Both the slope of linear regression and the measured hardness increase monotonically to the ion fluence, which can be described by logistic equations. Moreover, a linear relationship between the regression slope as a micromechanical characterization and the hardness as a macroscopic mechanical property is constructed. It is also found that the maximum resolved shear stress of the irradiated samples is larger than that of the unirradiated samples, as the dislocation loops are pinned by the irradiation-induced defects. Our results indicate that the nanoindentation pop-in phenomenon combined with a statistical analysis can serve as a characterization method for the mechanical properties of ion-irradiated materials.

Nanoindentation of ion-irradiated nuclear structural materials and model alloys has received considerable interest in the published literature. In the reported studies, the materials were typically exposed to irradiations using a single ion energy varying from study to study from below 1 MeV to above 10 MeV. However, systematic investigations into the effect of self-ion energy are still insufficient, meaning that the possibilities to gain insight from systematic energy variations are not yet exhausted. We have exposed pure Fe, ferritic Fe-9Cr, martensitic Fe-9Cr and the ferritic-martensitic reduced-activation steel Eurofer 97 to ion irradiations at 300°C using 1, 2 and 5 MeV Fe2+ ions as well as 8 MeV Fe3+ ions and applied nanoindentation, using a Berkovich diamond indenter, to characterize as-irradiated samples and unirradiated references. The effect of the ion energy on the measured nanoindentation response is discussed for each material. Two versions of a primary-damage-informed model are applied to fit the measured irradiation-induced hardening. The models are critically compared with the experimental results also taking into account reported microstructural evidence. Related ion-neutron transferability issues are addressed.

MAX phases are nano-lamellar composite materials of the form Mn+1AXn, where n is 1, 2 or 3; M an early transition metal; A is an A-group element and X is carbon or nitrogen [1,2]. An interesting combination of metallic and ceramic properties as well as potential applications in spintronics [1,3] led to significant research interest in MAX phases. Literature on the effect of systematic disordering of the nano-laminar structure on the magnetic and transport properties is still limited. In particular, MAX phase systems doped with magnetic ions via ion-irradiation may result in large variations of the magneto-transport properties. Here we observe the magneto-transport properties and attempt to separate the contributions of structural changes due to the irradiation and magnetic effects due to the doping on the magneto-transport. A prototype material is Cr2AlC, formed from a unit cell of Cr2C sandwiched between atomic planes of Al. In this work, we study 50 nm and 500 nm thick thin films of Cr2AlC grown on Si (111) by sputtering and subsequent annealing. Structural characterization using X-ray Diffraction in Bragg-Brentano geometry shows a pronounced MAX phase, confirmed by the occurrence of the 002 superlattice reflection. The films were irradiated with Co+ at 450 (50) keV for the 500 (50) nm thick films. The Co+ fluence varied between 1×10^12 - 1×10^15 ions.cm^-2, in full order steps. The Co+ irradiation led to a gradual suppression of the 0002 superstructure reflection, while preserving the fundamental peaks, implying the intermixing of the nano-laminar MAX phase structure. The magnetic properties are characterized using vibrating sample magnetometry at low temperatures, showing an increasing paramagnetic behavior as the Co+-fluence increases. In comparison, magneto-resistance measurements show that for the 500 nm film thickness, the magnetoresistance reaches up to 3 % (10 T) for 100 K, at an optimized Co+-fluence of 5×10^13 ions.cm^-2. The above results suggest that in the low-fluence regime, the irradiation-induced disorder remains sufficiently low to obtain pronounced magneto-resistance values. Understanding the defect state in the optimized MAX phase films will shed light on the magneto-transport mechanisms in these nano-laminated materials.

Similar to their bulk 3D counterparts, the properties of two-dimensional (2D) materials can be tuned by controllable introduction of impurities and defects using beams of energetic ions, which requires complete microscopic understanding of their response to ion irradiation. The behavior of 2D materials under ion beam is also interesting in the context of their applications in radiation-hostile environments such as cosmic space. While irradiation effects in 3D systems are well understood, a growing body of experimental facts indicate that many concepts of energetic particle-solid interaction developed for 3D materials are not applicable to 2D systems due to their very geometry, or require substantial modifications. In this Chapter, we discuss at length the response of 2D materials to ion irradiation in different regimes with the main focus on the role of reduced dimensionality. We illustrate the differences between the impact of ions on 3D and 2D materials by examples taken from the recent theoretical and experimental studies on the response of 2D materials to ion irradiation and outline general trends in their behavior under irradiation. Finally, we discuss how ion beams can be used to engineer the structure and properties of 2D materials.

Ion irradiation reduces oxidized graphene but causes morphological and structural changes in individual sheets. Graphene oxide (GO) films were irradiated under vacuum with ion beams having different atomic numbers and energies in the range (2–16) MeV. The structural and morphological changes undergone by the individual sheets of reduced graphene oxide (rGO) were analyzed by transmission electron microscopy and Raman spectroscopy. In particular, the electron diffraction highlights the deformations of the sheets through the deformation of the diffraction spots. A quantitative structural evaluation of such features was carried out using a new method based on the analysis of the radial and azimuth profiles extracted from the electron diffraction pattern. The spots deformation involves both the direction normal to the reciprocal lattice vectors and the parallel one. The former deformation is related to the non-planarity of the surface, the latter to the rearrangement of the deformed lattice. Experimental evidence indicates that there are many different orientations present within the electron beam with a diameter of less than one micron and that the surface normal of the sheet must vary in all directions. This is the result of a microscopic roughness inside the sheets. The progressive deformation of the spots depends on the absorbed ion dose. The morphological analysis, carried out at high resolution on rGO sheets, confirms structural results: the rGO sheets take on a static not flat but rippled configuration. Accentuated ripples are dose dependent.

Ion beam induced mixing (IBM) can be used for making protecting coating layers at room temperature. We have studied the production of tungsten-carbide, having high strength and low friction, by IBM since this material is also a candidate for protective coatings. WC rich layers have been produced by irradiating C/W multilayer of various structures (with individual layer thicknesses from 10 to 20 nm) by noble gases using medium energy projectiles. The resulting alterations of the samples have been measured by Auger electron spectroscopy (AES) depth-profiling. TRIDYN simulations, with some parametrization, were applied to determine the elemental in-depth distribution after IBM; the compound formation was calculated by a simple model. The calculated and measured depth profiles were compared and excellent agreement has been found for a rich dataset differing in layer structures, projectiles, ion fluences and energies. The good agreement in a wide parameter range validates our procedure and allows the design of the WC-rich layers and also enables the significant decrease of the experimental work.

We present the Dual-beam ion irradiation facility for FUsion materials (DiFU) developed at Ruđer Bošković Institute in Zagreb, Croatia. It has a versatile setup which allows irradiation of fusion materials samples by one or two ion beams as well as other similar experiments. Two beamlines come to the DiFU chamber at an angle of 170 between them, from 6 MV HVE Tandem VDG and 1 MV HVE Tandetron accelerator. Ion beam handling and scanning systems enable fast electrostatic scanning of the beams over the sample at kHz frequencies, and irradiation of areas up to 30x30 mm2. The sample holder enables XYZ positioning of heated, cooled or room temperature samples. Ion fluxes are measured indirectly by insertion of two large Faraday cups in ion beams and the ion flux is also monitored continuously by two sets of XY slits. Conditions during irradiation are monitored by a set of thermocouples, an IR camera, a high-sensitive video-camera, and a residual gas analyser. The DiFU facility has been developed according to ASTM standard E521-16 [1] with support from EUROfusion, the IAEA and the Croatian Science Foundation. Ion beam irradiation can be used to emulate neutron irradiation effects in reactors [2]. Dual-beam facilities such as this are especially important for applications in fusion materials due to their ability to simultaneously reproduce the effects of radiation damage and helium or hydrogen formation inside a fusion power plant. The Tandetron accelerator can be used for light ion implantation, while the VDG damages the material with heavy ions. Particular care has been dedicated to mitigating carbon contamination during irradiation [3], an issue which has been shown to significantly affect the results of post-irradiation characterizations of materials [4]. Research into this effect is still ongoing. Material irradiation experiments conducted include a novel method of creating a temperature gradient in the material [5], as well as continuous irradiations of more than 24h to achieve a high doses in the range of 10 dpa [6]. The setup is also used in other irradiation or implantation experiments where the precise determination of fluence and a broad beam are needed. [1] ASTM E521-16, “Standard practice for investigating the effects of neutron radiation damage using charged-particle irradiation”, ASTM International, West Conshohocken, PA, 2016 [2] ZINKLE, S. J., SNEAD, L.L., Opportunities and limitations for ion beams in radiation effects studies, bridging critical gaps between charged particle and neutron irradiations. Scr. Mat. 143 (2018): 154-160 [3] DUNATOV, T. “Mitigating carbon contamination in heavy ion irradiation” Poster No. 57, poster presented at International Conference on Fusion Reactor Materials, Granada 2020 (online) [4] GIGAX, J. G., KIM, H., AYDOGAN, E., GARNER, F.A., MALOY, S., SHAO, L. Beam-contamination-induced compositional alteration and its neutron-atypical consequences in ion simulation of neutron-induced void swelling. Mater. Res. Lett., 5(7), (2017). 478-485 [5] HARDIE, C., LONDON, A., LIM, J. J. H., BAMBER R., TADIĆ T., VUKŠIĆ, M., FAZINIĆ, S., Exploitation of thermal gradients for investigation of irradiation temperature effects with charged particles, Sci. Rep. 9, 1 (2019) 1-10. [6] DI FONZO, F. et al., Italian institute of technology, unpublished data

Monoclinic ZrO2 was irradiated by 1.46 GeV Au ions using the UNILAC accelerator at the GSI Helmholtz Centre for Heavy Ion Research (Darmstadt, Germany), and the irradiated material was structurally characterized by high-resolution synchrotron X-ray and neutron total scattering experiments coupled with pair distribution function (PDF) analysis. The monoclinic-to-tetragonal phase transformation of swift heavy ion-irradiated ZrO2 has been widely studied, yet details of how irradiation drives the transformation proceeds at the atomic scale remain unclear. Using PDF analysis, we have probed the local structure of ZrO2 before and after irradiation to a fluence of 5×1012 and 1×1013 ions cm-2 and revealed that the long-range structure is described best using the previously reported tetragonal high-temperature phase; however, the local atomic arrangement cannot be fully described by this structural model alone at the level of because it cannot explain the observed nearest neighbor bonds and coordination polyhedra. A metastable, orthorhombic high-temperature phase, distinct from the monoclinic and tetragonal phases, must be included in the refinement of the local structure after ion irradiation. This phase was predicted but never observed because of its inherent metastable character in the structural transformation pathway between the monoclinic and tetragonal polymorphs but has never been experimentally confirmed. This orthorhombic phase, which quickly loses correlation beyond the nanoscale, is an essential ingredient to explain the structure of zirconia across the relevant range of length scales. This study contributes to an improved understanding of the mechanisms of the ion beam-induced crystalline-to-crystalline transformation polymorphism in ZrO2 and describes how orthorhombic structural building blocks organize across the mesoscale to yield the tetragonal long-range ZrO2 structure. Interestingly, this structural heterogeneity has also been reported in other complex oxides after swift heavy ion irradiation.

Fe-Cr alloys constitute the model systems for the investigation of radiation damage effects in ferritic-martensitic steels which are candidate structural materials for fusion reactors. In the current study Fe-10at%Cr alloy films of 70 nm thickness were irradiated by 490 keV Fe+ ions at 300 °C at doses ranging from 0.5 up to 20 displacements per atom (dpa). The Fe+ ion energy chosen corresponds to the energy of primary Fe(Cr) knock-on atoms from 14 MeV neutrons. The irradiation effects were investigated employing X-ray diffraction and X-ray and polarized neutron reflectivity. The irradiation produced dose dependent: a) lattice constant increase, b) grain size growth and c) Cr depletion in the matrix. These changes occur largely up to 4 dpa and afterwards the system attains a dynamic equilibrium.

The stability of structural materials in extreme nuclear reactor environments—with high temperature, high radiation and corrosive media—directly affects the lifespan of the reactor. In such extreme environments, an oxide layer on the metal surface acts as a passive layer protecting the metal underneath from corrosion. To predict the irradiation effect on the metal layer in these metal/oxide bilayers, nondestructive depth-resolved positron annihilation lifetime spectroscopy (PALS) and complementary transmission electron microscopy (TEM) were used to investigate small-scale defects created by ion irradiation in an epitaxially grown (100) Fe film capped with a 50 nm Fe2O3 oxide layer. In this study, the evolution of induced vacancies was monitored, from individual vacancy formation at low doses—10^-5 dpa—to larger vacancy cluster formation at increasing doses, showing the sensitivity of positron annihilation spectroscopy techniques. Furthermore, PALS measurements reveal how the presence of a metal-oxide interface modifies the distribution of point defects induced by irradiation. TEM measurements show that irradiation induced dislocations at the interface is the mechanism behind the redistribution of point defects causing their accumulation close to the interface. This work demonstrates that the passive oxide layers formed during corrosion impact the distribution and accumulation of radiation induced defects in the metal underneath, and emphasizes that the synergistic impact of radiation and corrosion will differ from their individual impacts.

Advanced materials such as tungsten fibre-reinforced composites allow to overcome severe weaknesses of the baseline materials for plasma-facing components — copper and tungsten. The effect of the fusion environment on the mechanical properties of these materials, e.g. the embrittlement by neutron irradiation, plays a key role for the development of future fusion reactors. To simulate this effect, high-energy ions are used as a substitute for the displacement damage by neutrons. We propose the use of very fine tungsten wire as a possibility of studying the influence of irradiation damage on the mechanical properties. This is possible as they allow full-depth irradiation of almost the entire volume despite the limited penetration depth of ions. Geometrical size effects are mitigated due to the nanoscale microstructure of the wire. In addition, similar wire is used in tungsten fibre-reinforced composites. Thus, the investigation of irradiated wire can directly be used for the prediction of the bulk composite properties. For the proof of this concept tungsten wire with a diameter of 16 μm was electrochemically thinned to 5 μm and irradiated with 20.5 MeV W6+ions. The mechanical properties were subsequently determined by macroscopic tensile testing. Irradiation to 0.3, 1 and 9 dpa did not lead to a change of the mechanical behaviour. Both strength and ductility, the latter indicated by the reduction of area, were similar to the as-fabricated state.

Progress in advanced fuels and waste forms requires unprecedented control of the design and organization of systems at the micro, meso, and nanoscale. In the last years, weberite-type oxides with the general formula A3BO7 (where A is a trivalent rare earth element and B is a pentavalent cation, such as Ta, Nb) have sparked interest in a number of technological applications due to their chemical and structural flexibility, which leads to a broad spectrum of physical properties, such as high ionic conductivity, ferroelectricity, and photocatalytic activity. In addition, weberite-type oxides have recently been linked to pyrochlore oxides (A2B2O7) because they share similar atomic building blocks that form after exposure to swift heavy ions. Here, we present a comprehensive ion irradiation study on weberite-type tantalate oxides (A3TaO7, A = Pr, Tb, Dy, Y, Yb), covering three major structural classes characterized by different long-range symmetries and organizations at the nano and mesoscale. Irradiation experiments were performed using 1.6 GeV Au ions at the X0 beamline of the GSI Helmholtz Center (Darmstadt, Germany). Samples were analyzed using the neutron total scattering technique at the Nanoscale-Ordered Materials (NOMAD) beamline at Oak Ridge National Laboratory and X-ray diffraction at the Advanced Photon Source (APS) at Argonne National Laboratory, respectively. The data analysis establishes a link between the material resistance to amorphization and the A-site cation ionic radius: smaller cations enhance radiation resistance to amorphization. Analyses of the neutron pair distribution function (PDF) establish that the pristine (unirradiated) local organization in these materials is a critical factor: indeed, ion beams are more susceptible to destroying the long-range order in orthorhombic Pr3TaO7 (Cmcm) than in Tb3TaO7 (Ccmm). Cubic Yb3TaO7 (an Fm-3m oxygen-deficient fluorite) does not display any long-range organization of the cations and vacancies though it does at the nanoscale: this system shows the highest radiation resistance and only extremes radiation levels trigger, besides a minor amorphization, the transformation another cubic structure, which was previously reported only during swift heavy ion irradiation of lanthanide sesquioxides (A2O3).

In this work, the radiation responses of Zr/Nb nanostructured metallic multilayers (NMMs) are studied. The nanostructures with different layer thicknesses were deposited on Si (1 0 0) substrate by using magnetron sputtering and are subjected to heavy-ion irradiation at room temperature with different fluences. Nanoindentation, XRD, SIMS, and Variable Energy Positron Annihilation Spectroscopy (VEPAS) techniques were used to study the changes in the hardness of the structures as well as the type and distribution of defects, and strain within the material as a function of damage. Our results suggest that the irradiation hardening is independent of the type of implanted ions, and its magnitude decreases with decreasing individual layer thickness indicating that the number of interfaces has a direct effect on the radiation tolerance enhancement. For thin layers with a periodicity of 27 nm (Zr/Nb27), a transition from hardening to softening occurs at high fluence, and a saturation point is reached in thick layers with a periodicity of 96 nm (Zr/Nb96). The as-deposited multilayer with the smaller periodicity experienced a significantly higher atomic-scale disorder which increases with ion irradiation compared to the multilayer with thicker individual layers. VEPAS reveals the vacancy defects before and after irradiation that contribute to the presented strain. Based on the findings, thin nanostructured Zr/Nb multilayered structures possess excellent radiation resistance due to the high density of interfaces that act as sinks for radiation-induced point defects.

Hardening of Fe-9%Cr alloys exposed to irradiation with Fe²⁺ ions of two different energies, 1 and 5 MeV, is investigated using nanoindentation. The limited penetration depth of the ions causes steep damage gradients in the near-surface volumes of the irradiated samples. This damage gives rise to graded microstructures resulting in depth-dependent irradiation hardening. Nanoindentation integrates the depth-dependent hardness over the indentation plastic zone. Our study combines quantitative analysis of the ion-irradiated microstructures with the determination of the full depth dependence of irradiation hardening. The microstructure-informed model incorporates direct experimental evidence revealed by a former investigation using cross-sectional scanning transmission electron microscopy. For both ion energies, the observed microstructures consist of dislocation loops with band-like distributions and are concluded to be the dominant source of the measured irradiation-induced hardening. The model predictions are found to be in reasonable agreement with the as-measured nanoindentation response. The comparison of hardening predictions with different kinds of superposition rules of hardening contributions suggests linear superposition as the most appropriate selection under the present conditions. The possible transferability of these results to neutron irradiation is also discussed.

MAX phases are nano-lamellar composite materials of the form Mn+1AXn, where n is 1, 2 or 3; M an early transition metal; A is an A-group element and X is carbon or nitrogen[1,2]. An interesting combination of metallic and ceramic properties as well as potential applications in spintronics [1,3] led to significant research interest in MAX phases. Literature on the effect of systematic disordering of the nano-laminar structure on the magnetic and transport properties is still limited. In particular, MAX phase systems doped with magnetic ions via ion-irradiation may result in large variations of the magneto-transport properties.Here we observe the magneto-transport properties and attempt to separate the contributions of structural changes due to the irradiation and magnetic effects due to the doping on the magneto-transport. A prototype material is Cr2AlC, formed from a unit cell of Cr2C sandwiched between atomic planes of Al. In this work, we study 50 nm and 500 nm thick thin films of Cr2AlC grown on Si(111) by sputtering and subsequent annealing.Structural characterization using X-ray Diffraction in Bragg-Brentano geometry shows a pronounced MAX phase, confirmed by the occurrence of the 002 superstructure reflection. The films were irradiated with Co+ at 450 (50) keV for the 500 (50) nm thick films. The Co+ fluence varied between 1E12-1E15 ions.cm-2, in full order steps. The Co+ irradiation led to a gradual suppression of the 002 superstructure reflection, while preserving the fundamental peaks, implying the intermixing of the nano-laminar MAX phase structure. The magnetic properties are characterized using vibrating sample magnetometry at low temperatures (Fig.1a), showing an increasing paramagnetic behavior as the Co+ fluence increases. In comparison, magneto-resistance measurements (Fig.1b-c) show that for the 500 nm film thickness, the magnetoresistance reaches up to 3 % (10 T) for 100 K, at an optimized Co+ fluence of 5E13 ions.cm-2. The above results suggest that in the low-fluence regime, the irradiation induced disorder remains sufficiently low to obtain pronounced magneto-resistance values.Understanding the defect state in the optimized MAX phase films will shed light on the magneto-transport mechanisms in these nano-laminated materials.

FeCrAl is regarded as one of the most promising cladding materials for accident-tolerant fuel at nuclear fission reactors due to its comprehensive properties of inherent corrosion resistance, excellent irradiation resistance, high-temperature oxidation resistance, and stress corrosion cracking resistance. In this work, the irradiation response of FeCrAl irradiated by 2.4 MeV He2+ ions with a fluence of 1.1 × 1016 cm−2 at room temperature was studied using X-ray diffraction, transmission electron microscopy, and nanoindentation. The characterization results of structural and mechanical properties showed that only black-dot defects exist in irradiated FeCrAl samples, and that the hardness of the irradiated samples was 11.5% higher than that of the unirradiated samples. Similar to other types of radiation defects, black-dot defects acted as fixed defect obstacles and hindered the movement of slip dislocations moving under the applied load, resulting in a significant increase in the hardness of FeCrAl. Importantly, this work points out that irradiation-induced black-dot defects can significantly affect the mechanical properties of materials, and that their contribution to radiation hardening cannot be ignored.

High-energy heavy ion irradiation is a very useful tool for the nanostructuring of 2D materials because defects can be introduced in a controlled way. This approach is especially attractive for the mass production of graphene nanomembranes when nanopore size and density can easily be tuned by ion irradiation parameters such as ion energy and applied fluence. Therefore, understanding the basic mechanisms in nanopore formation due to high-energy heavy ion impact is of the highest importance. In the present work, we used Raman spectroscopy to investigate the response of bilayer and trilayer graphene to this type of irradiation. Spectra obtained from graphene samples irradiated with 1.8 MeV I, 23 MeV I, 3 MeV Cu, 18 MeV Cu, and 12 MeV Si beams were analysed using the Lucchese model. It was found that the efficiency of damage production scales strongly with nuclear energy loss. Therefore, even for the most energetic 23 MeV I beam, the electronic energy loss does not contribute much to damage formation and ion tracks are unlikely to be formed.