Previous studies of nickel hydroxide (Ni(OH)2) powders have shown that either heating or mechanical grinding can result in complete de-hydroxylation, leading to conversion to nickel oxide (NiO). In both cases, this process appears to occur in one stage, without evidence for any intermediate compounds being formed. During studies of Ni(OH)2 powders for applications in the positive electrodes of Ni metal hydride (NiMH) rechargeable batteries, using transmission electron microscopy (TEM), we have observed significant changes caused by exposure to the highly energetic electron beam used for imaging and analysis. It is shown here, using electron energy-loss spectroscopy (EELS), that de-hydroxylation under electron irradiation occurs in two stages, with nickel oxy-hydroxide (NiOOH) being formed at the intermediate stage.

Betavoltaics (BV) cells (or nuclear batteries) have long-lasting power and high volumetric energy densities that open a broad range of applications that are not currently available, especially in low-power electronics for the internet-of-things, internal medical devices, and harsh environments. The introduction of very low-power electronics has opened up a market for the wide and accepted use of BV cells. As BVs have potentially decades-long useful lifetimes and are anticipated to be used in harsh environments, a method to describe accelerated contact aging has been developed. Monte Carlo radiation simulations show that energy can be deposited in the interface 10-50 times faster than real-world applications. The models can be used to design contact aging experiments for BV cell deployments.

The dynamics of the gas release at thermal oxidation of the two-phase systems of 30% solution of tri-n-butyl phosphate (TBP) in isoparaffinic diluent Isopar M – aqueous solution of 4.3, 8.2 and 12 mol/L of HNO3 has been investigated within the temperature range from 70°C to 110°C. The effect of pre-irradiation of the system TBP–Isopar-M–HNO3 on the kinetics of its thermolysis has been determined. All of the samples were irradiated with an electron accelerator at a dose rate of 10 kGy/h up to integrated doses of 0.5, 1 and 2 MGy. The parameters of heat and gas emission during thermolysis of the tested extraction system in an open apparatus have been determined experimentally. It has been demonstrated, that there are no conditions for extension of autocatalytic oxidation under heat treatment of two-phase extraction systems in open vessels.

New developments in manufacturing and automation, from three-dimensional printing to the “Internet of things,” signify dramatic changes in our society. The push toward quantum materials is driving device fabrication toward atomic precision. Recent results suggest that scanning transmission electron microscopy (STEM) with sub-angstrom scale beams could offer a solution. However, a detailed theoretical understanding of the interaction of the electron beam with solids is needed to form a basis for new technology. This article summarizes the existing literature on electron-beam interactions with solids with a focus on irreversible transformation. We further suggest that the theoretical framework of a two-temperature model developed for fast ion damage in solids could be applicable to predicting the effects of fast electrons. Recent results from STEM-directed epitaxial growth on crystalline–amorphous interfaces are discussed in detail. Finally, perspectives on the development of this field in the near future are offered.

Electron-beam (e-beam) irradiation damage is often regarded as a severe limitation to atomic-scale study of two-dimensional (2D) materials using electron microscopy techniques. However, energy transferred from the e-beam can also provide a way to modify 2D materials via defect engineering when the interaction of the beam with the sample is precisely controlled. In this article, we discuss the atomic geometry, formation mechanism, and properties of several types of structural defects, ranging from zero-dimensional point defects to extended domains, induced by an e-beam in a few representative 2D materials, including graphene, hexagonal boron nitride, transition-metal dichalcogenides, and phosphorene. We show that atomic as well as line defects and even novel nanostructures can be created and manipulated in 2D materials by an e-beam in a controllable manner. Phase transitions can also be induced. The e-beam in a (scanning) transmission electron microscope not only resolves the intrinsic atomic structure of materials with defects, but also provides new opportunities to modify the structure with subnanometer precision.

Pulsed electron beam ablation (PEBA) has proven to be a promising and powerful technique for the growth of high quality thin films. Pulsed electron beam film deposition consists of many physical processes including target material heating, target ablation, plasma plume expansion, and film growth on a substrate. Plasma plume expansion into a vacuum or an ambient gas is a fundamental issue in PEBA as the quality of thin films deposited onto the substrate depends on the composition, energy and density of particles ejected from the target. In the present study, gas-dynamics equations are solved to investigate plasma expansion induced by interaction of a nanosecond electron beam pulse (∼100 ns) with a graphite target in an argon atmosphere at reduced pressure. The spatio-temporal profiles of the temperature, pressure, velocity, and density of the plasma plume are numerically simulated for a beam efficiency of 0.6 and accelerating voltage of 15 kV. The preliminary results show a rich variety of behaviors. The model is validated by comparing some of the obtained simulation results with experimental data available in the literature.

Cubic boron nitride (cBN) is a synthetic wide band gap material that has attracted attention due to its high thermal conductivity, optical transparency and optical emission. In this work, defects in cBN have been investigated using experimental and theoretical X-ray absorption near edge structure (XANES). Vacancy and O substitutional defects were considered, with O substituted at the N site (ON) to be the most energetically favorable. All defects produce unique signatures in either the B or N K-edges and can thus be identified using XANES. The calculations coupled with electron-irradiation / annealing experiments strongly suggest that ON is the dominant defect in irradiated cBN and remains after annealing. This defect is a likely source of optical emission in cBN.

The dynamics of gas evolution during the thermal oxidation of 30% solutions of tri-n-butyl phosphate (TBP) in Isopar-M saturated with 4.3, 8.2 and 12.0 mol/L nitric acid was investigated in open vessels in the temperature range of 70°C to 150°C. The volume of the released gases has been measured. The influence of the pre-irradiation by accelerated electrons has been determined for the thermolysis and accumulation of liquid products of TBP degradation in the system TBP-Isopar-M-HNO3. The temperature borders of oxidation processes transition to autocatalytic regime have been estimated. It has been shown, that the conditions resulting in growth of autocatalytic oxidation do not exist under heating of single-phase systems in open vessels.

The two-phase systems of pure diluent FS-13 – aqueous solution of 14 mol/L nitric acid and 0.02 mol/L solution of CMPO in diluent FS-13 – aqueous solution of 14 mol/L HNO3 were studied at autoclave temperatures 170 °C and 200 °C. The effect of pre-irradiation on the kinetics of thermolysis was determined. All samples were irradiated using an electron accelerator at a dose rate of 10 kGy/h up to absorbed doses of 0.1, 0.5 and 1 MGy. The parameters of heat and gas emissions were determined during thermolysis of the studied extraction system in a closed apparatus. It has been shown that the conditions required for the growth of autocatalytic oxidation are not created during heating of the two-phase systems in closed vessels even for the extraction systems contacted with 14 mol/l HNO3 for two weeks.

Besides the high spatial resolution achieved in aberration-corrected scanning transmission microscopy, beam-induced dynamic effects have to be considered for quantitative chemical characterization on the level of single atomic columns. The present study investigates the influence of imaging conditions in an aberration-corrected scanning transmission electron microscope on the beam-induced atomic migration at a complex Ag-segregated, nanofaceted Cu grain boundary. Three distinct imaging conditions including static single image and serial image acquisition have been utilized. Chemical information on the Ag column occupation of single atomic columns at the grain boundary was extracted by the evolution of peak intensity ratios and compared to idealized scanning transmission electron microscopy image simulations. The atomic column occupation is underestimated when using conventional single frame acquisition due to an averaging of Ag atomic migration events during acquisition. Possible migration paths for the beam-induced atomic motion at a complex Cu grain boundary are presented.

PtCu nanoparticles were synthesized with different pH and support conditionsusing radiochemical process. The nanoparticle structures were characterized bytransmission electron microscopy, inductively coupled plasma atomic emissionspectrometry, X-ray absorption spectroscopy, and X-ray diffraction techniques.The nanoparticle structure was relevant to the pH of the precursor solutions.The lattice parameter of PtCu alloy increased in high pH samples, whichindicates the critical effect of metal ion adsorption in precursor solution onnanoparticle structure.

Controlling the bending properties of ionic polymer-metal composites may immediately affect their implementation in robotics and medicine. In the present work, we propose a direct patterning method for the ionic polymer Nafion using conventional electron-beam writing. In a proof-of-concept study, we show that patterns of arbitrary geometry and sizes between 1 µm and 50 µm can be engraved into the polymer surface without using resists. Pattern depth can be deliberately controlled by adjusting the exposure dose. The patterns were stable even after prolonged immersion in ionic solution. The presented technique therefore opens up the possibility to create unique electrode geometries and to investigate independently the effect of pattern size, density, depth as well as geometry on ionic polymer-metal composite bending.

This article reviews the application of nanomaterials for radiation shielding to protect humans from the hazards of radiation in space. The focus is on protection from space radiation, including galactic cosmic radiation (GCR), solar particle events (SPEs), and neutrons generated from the interactions of the GCR and SPEs with the intervening matter. Although the emphasis is on protecting humans, protection of electronics is also considered. There is a significant amount of work in the literature on materials for radiation shielding in terrestrial applications, such as for neutrons from nuclear reactors; however, the space environment poses additional and greater challenges because the incident particles can have high charges and extremely high energies. For materials to be considered for radiation shielding in space, they should perform more than just the radiation-shielding function; hence the emphasis is on multifunctional materials. In space, there is also the need for materials to be very lightweight and capable of surviving temperature extremes and withstanding mechanical loading. Nanomaterials could play a significant role as multifunctional radiation-shielding materials in space.

In this paper, we discuss the characteristics of the InGaP/GaAs heterojunction phototransistors (HPTs) before and after the electrical stress at room temperature and assess the effectiveness of the emitter-ledge passivation. Although an electrical stress given to the phototransistors by keeping a collector current density of 37 A/cm2 for 1 hour at room temperature was too small to affect the room-temperature common-emitter current gain and photocurrent of both HPTs with and without the emitter-ledge passivation, they showed a significant decrease at 420 K due to the room-temperature electrical stress. Nevertheless, the room-temperature common-emitter current gain and photocurrent of the HPT with the emitter-ledge passivation were still higher than those of the HPT without the emitter-ledge passivation. The effectiveness of the emitter-ledge passivation against the electrical stress was more significant than that on the current gain in the dark. In addition to the electrical stress experiment, for a potential application of the InGaP/GaAs HPTs in space, we will irradiate the HPTs with 1-MeV electrons at the Japan Atomic Energy Agency. Both current gain and photocurrent decreased significantly after the electron irradiation. In contrast to the electrical stress, the damage due to the high-energy electron irradiation is a bulk-related phenomenon, and the emitter-ledge passivation does not seem to suppress the degradation.

CIGS thin films were irradiated with 100 or 250 keV electrons to reveal the radiation defect by analyzing PL measurement. The PL intensity decreased due to non-radiative recombination defects induced by electron irradiation. Furthermore, the intensity 0.8 eV peak of the PL spectrum was observed from CIGS films irradiated with 250 eV electrons and is said to correspond to In-antisite defects in CIGS materials. The defects can usually change into InCu-VCu complex defects combined with VCu, since the formation energy of the complex defect is lower than that of each defect. Cu interstitial defects induced by 250 keV electron irradiation would diffuse to VCu of the complex defect, whereupon the complex defect might become an In-antisite defect due to 250 keV electron irradiation.

We use transmission electron microscopy (TEM) for in situ studies of electron-beam-induced crystallization behavior in thin films of amorphous transition metal silicon carbides based on Zr (group 4 element) and Nb (group 5). Higher silicon content stabilized the amorphous structure while no effects of carbon were detected. Films with Nb start to crystallize at lower electron doses than the Zr-containing ones. During the crystallization, equiaxed MeC grains are formed in all samples with larger grains for ZrC (∼5 nm) compared to NbC (∼2 nm). The phenomenon of self-terminating crystallization at a dimension of 2–5 nm is explained by segregation of Si that is expelled from growing metal carbide grains into the surrounding amorphous phase matrix, which limits diffusion of the metal and carbon.

Results are presented of a study of {113}-defect formation in Si nanowires with diameters ranging from 50 to 500 nm. The Si nanowires, used for the processing of tunnel-FET's, are etched into a moderately doped epitaxial Si layer on a heavily doped n-type Si substrate. {113}- defects are created in situ by 2 MeV e-irradiation at temperatures between room temperature and 375 °C in an ultra high voltage electron microscope. The observations are discussed in the frame of intrinsic point defect out-diffusion and interaction with dopant atoms.

Carbon supported Pt-SnO2 electrocatalysts with different Sn/Pt molar ratios were prepared by an electron beam irradiation method. Dissolved gas conditions in the vials irradiated with electron beam were controlled to air or Ar. The results of the material analyses showed that both Pt and SnO2 were immobilized onto carbon support in all catalysts. Bubbling Ar to the precursor solution led to steady change of metal contents in response to the precursor concentrations. The ethanol oxidation activity plotted against Sn/Pt ratio behaved differently with dissolved gas condition of the vial. This difference is discussed with supposed existing state of SnO2 in connection with the reduction process of Pt and Sn.

A molecular dynamics (MD) simulation was performed to study the interaction volume of electron beam in carbon nanomaterials. The interaction between incident electron and carbon atom in the target materials during electron irradiation is introduced by the relativistic binary collision theory. The motion of each atom in the material under electron irradiation is calculated with the MD simulation. The primary energy dependence of the interaction volume in the carbon nanotube and the multi-layered graphene are studied. The secondary damages caused by the knock-on atoms are also discussed.

Electron microscopes are proving themselves indispensible tools in the world of nanotechnology. In this brief overview, we explore the potential of electrons within in situ transmission electron microscopy (TEM) with the electrons provided either from the imaging electron beam or from electrical currents across contacted specimens to nanoengineered graphene based on work at our labs. The use of electrons is demonstrated to be enormously versatile to pattern, heal, and even fabricate graphene. In essence, electrons provide a useful engineering tool box that with further development will enable device fabrication and modification inside a TEM, thus allowing one to study structure–property relationships of graphene as well as other low dimensional materials in near real time with atomic precision.