Nanowires can be manipulated using an ion beam via a phenomenon known as ion-induced bending (IIB). While the mechanisms behind IIB are still the subject of debate, accumulation of point defects or amorphisation are often cited as possible driving mechanisms. Previous results in the literature on IIB of Ge and Si nanowires have shown that after irradiation the aligned nanowires are fully amorphous. Experiments were recently reported in which crystalline seeds were preserved in otherwise-amorphous ion-beam-bent Si nanowires which then facilitated solid-phase epitaxial growth (SPEG) during subsequent annealing. However, the ion-induced alignment of the nanowires was lost during the SPEG. In this work, in situ ion irradiations in a transmission electron microscope at 400°C and 500°C were performed on Ge and Si nanowires, respectively, to supress amorphisation and the build-up of point defects.Both the Ge and Si nanowires were found to bend during irradiation thus drawing into question the role of mechanisms based on damage accumulation under such conditions. These experiments demonstrate for the first time a simple way of realigning single-crystal Ge and Si nanowires via IIB whilst preserving their crystal structure.

Coating nuclear fuel cladding alloys with hard thin films has been considered as an innovative solution to increase the safety of nuclear reactors, in particular during a of loss-of-coolant accident (LOCA). In this context, and due to its suitable mechanical properties and high corrosion resistance, titanium nitride thin films have been proposed as candidate coatings for zirconium alloys in new accident tolerant fuels for light water reactors. Although the properties of TiN hard coatings are known to be adequate for such applications, the understanding of how the exposure to energetic particle irradiation changes the microstructure and properties of these thin films is still not fully understood. Herein, we report on heavy ion irradiation in situ within a Transmission Electron Microscopy of magnetronsputtered TiN thin films. The coatings were irradiated with 134 keV Xe + ions at 473K to a fluence of 6.7×10 15 ions•cm −2 corresponding to 6.2 displacements-per-atom where significative microstructural alterations have been observed. Post-irradiation analytic characterisation with Energy Filtered TEM and Energy Dispersive X-ray spectroscopy carried out in a Scanning Transmission Electron Microscope indicates that TiN thin films are subjected to Radiation Induced Segregation. Additionally, the nucleation and growth of Xe bubbles appears to play a major role in the dissociation of the TiN thin film.

The miniaturisation of technology increasingly requires the development of both new structures as well as novel techniques for their manufacture and modification. Semiconductor nanowires (NWs) are a prime example of this and as such have been the subject of intense scientific research for applications ranging from microelectronics to nano-electromechanical devices. Ion irradiation has long been a key processing step for semiconductors and the natural extension of this technique to the modification of semiconductor NWs has led to the discovery of ion beam-induced deformation effects. In this work, transmission electron microscopy with in situ ion bombardment has been used to directly observe the evolution of individual silicon and germanium NWs under irradiation. Silicon NWs were irradiated with either 6 keV neon ions or xenon ions at 5, 7 or 9.5 keV with a flux of 3 × 10 ions cm s. Germanium NWs were irradiated with 30 or 70 keV xenon ions with a flux of 10 ions cm s. These new results are combined with those reported in the literature in a systematic analysis using a custom implementation of the transport of ions in matter Monte Carlo computer code to facilitate a direct comparison with experimental results taking into account the wide range of experimental conditions. Across the various studies this has revealed underlying trends and forms the basis of a critical review of the various mechanisms which have been proposed to explain the deformation of semiconductor NWs under ion irradiation.

During ion irradiation which is often used for the purposes of band gap engineering, nanostructures can experience a phenomenon known as ion-induced bending (IIB). The mechanisms behind this permanent deformation are the subject of debate. In this work, germanium nanowires are irradiated with 30 or 70 keV xenon ions to induce bending either away from or towards the ion beam. By comparing experimental results with Monte-Carlo calculations, the direction of the bending is found to depend on the damage profile over the cross-section of the nanowire. After irradiation, the nanowires are annealed at temperatures up to 440°C triggering solid-phase epitaxial growth (SPEG) causing further modification to the deformed nanowires. After IIB, it is observed that nanowires which had bent away from the ion beam then straighten during SPEG whilst those which had bent towards the ion beam bend even more. This is attributed to differences in the mechanisms responsible for the ion-beam-induced bending in opposite directions. Thus, the results reported here give insights into the mechanisms causing the IIB of nanowires and demonstrate how to predict the evolution of nanowires under irradiation and annealing. Finally, they show that, under certain conditions, the bending can even be removed via SPEG.

A high performance and stable Li-ion conductive solid electrolyte is one of the key components for the future all-solid-state batteries with metallic lithium anodes. Phosphate, oxide and phosphosulfide-based inorganic solid electrolytes are currently under development. High ambient temperature Li-ion conductivities amounting up to [Formula: see text] S cm[Formula: see text] for the best performing electrolytes distinguish the phosphosulfides from the other material systems. Part I of the review starts with the motivation and background for the development of Li-phosphosulfide electrolytes followed by an overview of four different types of phosphosulfide electrolytes; the Li–P–S, thio-LiSICon, LGPS and the Argyrodite-type electrolytes. The core of part I is concerned with a detailed discussion of the phosphosulfide electrolyte types that have been under investigation already for a long time, the Li–P–S and the LiSICon. There is a multiplicity of different compositions within each of these types. The idea behind the outline of these sections is to point out the relations and differences between the different materials with respect to their chemistry related to the phase diagrams. Patterns for the relations among the materials identified in the phase diagrams are the base for a discussion of structure, processing and Li-ion conductivity within separate sections for each type and resulting in intra-type comparisons. The follow up part II will continue with a treatment of the more recently developed LGPS and Argyrodite-type electrolytes tracking the same concept, before addressing an inter-type comparison of ambient temperature Li-ion conductivities and the electrochemical stability of the electrolytes vs. metallic lithium. A final section in part II summarizes conclusions and provides perspectives for future research on Li-ion conductive phosphosulfide electrolytes.

Polyacrylonitrile-based carbon nanofibers (PAN-based CNFs) have great potential to be used for carbon dioxide (CO2) capture due to their excellent CO2 adsorption properties. The porous structure of PAN-based CNFs originates from their turbostratic structure, which is composed of numerous disordered stacks of graphitic layers. During the carbonization process, the internal structure is arranged toward the ordered graphitic structure, which significantly influences the gas adsorption properties of PAN-based CNFs. However, the relation between structural transformation and CO2 capture is still not clear enough to tune the PAN-based CNFs. In this paper, we show that, with increasing carbonization temperature, the arrangement of the PAN-based CNF’s structure along the stack and lateral directions takes place independently: gradually aligning and merging along the stack direction and enlarging along the lateral direction. Further, we correlate the structural arrangement and the CO2 adsorption properties of the PAN-based CNFs to propose a comprehensive structural mechanism. This mechanism provides the knowledge to understand and tailor the gas adsorption properties of PAN-based CNFs.

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SnO2 nanoparticles have frequently been reported as effective electrocatalysts for CO2 electroreduction to formate. However, in the literature, there is little knowledge of SnO2 nanoparticles that guarantee superior electrocatalytic performance. Hence, in this study, several SnO2 nanoparticles are compared with respect to their material properties, and correlations to the electrocatalytic performance are established. For comparison, three custom-made SnO2-electrocatalysts were prepared, reproducing frequently cited procedures in literature. Based on the comparison, it is found that hydrothermal, sol-gel, and solid-state synthesis provide quite different electrocatalysts, particularly in terms of the particle size and crystal lattice defect structure. Desirably small nanoparticles with a comparatively high number of lattice defects are found for the nanoparticles prepared by hydrothermal synthesis, which also provide the best electrocatalytic performance in terms of Faradaic efficiency for the electroreduction of CO2 to formate. However, despite the considerably smaller surface area, the commercial reference also provides significant electrocatalytic performance, e.g., in terms of the overall produced amount of formate, which suggests a surprisingly high surface area-specific activity for this material that is low on defects. Thus, defects do not appear to be the preferred reaction site for the CO2 electroreduction to formate on SnO2 in this case.