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A new wet chemistry approach, based on the hot-injection–thermolytic decomposition of the single-source precursor [Mo2O2S2(S2COEt)2] in oleylamine, is described for the production of nanodimensional 1H-MoS2@oleylamine. High quality freestanding MoS2 nanosheets capped with oleylamine have been prepared and subjected to detailed compositional analyses for the first time. The selection of the appropriate reaction temperatures (200–325 °C) in the simple yet robust procedure allows control of the lateral nanosheet dimensions which range from 4.5 to 11.5 nm, as 1H-MoS2@oleylamine entities which maintain a consistent chemical composition (MoS2·oleylamine0.28–0.33). This work provides the first example of atomic resolution STEM imaging of these fine-scale nanosheet materials, providing new insights into their morphology and demonstrating that those freestanding MoS2 nanosheets are pure, highly crystalline, randomly oriented monolayers. The 1H-MoS2@oleylamine samples were analyzed by attenuated total reflectance F...

The complex, nanometer-scale structural changes resulting from long-term α-particle bombardment of the mineral biotite are revealed for the first time using high-resolution transmission electron microscope (HRTEM) imaging. Radiohaloes are the product of high-energy α-particles emitted from radioactive inclusions penetrating into the surrounding mineral over long (∼1.8 Ga) timescales, resulting in intense discoloration attributed to ionization events and structural damage. HRTEM analysis of these radiohaloes reveals the long-term breakdown of the biotite structure into three distinct domains. Nanometer-scale, neo-phase regions of dilated and contracted mica structure, with periodicities comparable to 1:1 phyllosilicates, are bound by semi-amorphous, high-defect density domains. These are periodically interspersed with areas of near-original biotite structure. Across the halo region, damaged crystallites have become misoriented, revealing changes in the mica layer-to-layer spacing. This nanoscale response of the mica structure has profound implications for understanding the performance of phyllosilicates in barrier systems employed in the safe isolation of nuclear waste, as materials such as these will be relied upon to retard radionuclide migration over the lifetime of a geological disposal facility.

Small additions of rare-earth (RE) elements have been shown to have a powerful effect in modifying the texture of wrought magnesium alloys, giving a highly beneficial effect in improving their formability. Recent work has shown that segregation of RE atoms to grain boundaries is important in producing this texture change. In this work, two Mg-RE systems have been studied Mg-Y and Mg-Nd using high-resolution scanning transmission electron microscopy that permits both imaging and elemental analysis with a spatial resolution of better than 0.1 nm. The Mg-Y alloy, where the solubility and level of addition are relatively high, showed the RE texture change effect. This was accompanied by clustering of Y on the grain boundaries, consistent with previous studies of the Mg-Gd system. The Mg-Nd alloy, where the solubility and level of addition are relatively low, showed no texture change and no segregation. In this case, impurity elements binding the RE into insoluble particles, rendering it ineffective. The results are analyzed by modifying a previous model for the solute drag effect on boundaries expected due to the RE additions. This predicts that both Gd and Y will strongly inhibit boundary motion, with Gd being approximately twice as effective as Y.

Single wall carbon nanotubes (SWCNTs) and liquid-phase exfoliated multilayer graphene (MLG) material thin films were assembled at a polarizable organic/water interface. A simple, spontaneous route to functionalize/decorate the interfacial assembly of MLG and SWCNTs with noble metal nanoparticles, at the interface between two immiscible electrolyte solutions (ITIES), is reported. The formation of MLG- or SWCNT-based metal nanocomposites was confirmed using various microscopic (scanning electron, transmission electron, and atomic force microscopy) and several spectroscopic (energy dispersive x-ray and Raman spectroscopy) techniques. Increasing the interfacial deposition time of the metal nanoparticles on the assembled low-dimensional carbon material increased the amount of the metal particles/structures, resulting in greater coverage of the MLG or SWCNTs with metal nanoparticles. This low-cost and convenient solution chemistry based impregnation method can serve as a means to prepare nanoscale carbonaceous material-based metal nanocomposites for their potential exploitation as electro-active materials, e.g., new generation catalysts or electrode materials.

The early stages of nano-particulate formation in mechanically alloyed and annealed, precursor powders used to manufacture the legacy commercial oxide dispersion strengthened alloy PM2000, formerly produced by Plansee GmbH, have been investigated. Powders were analysed in both the as-mechanically-alloyed condition and after annealing over the temperature range 923–1423 K. The nucleation and growth of coherent nano-particles in the partially recovered, fine grained, ferritic matrix of powders annealed at temperatures as low as 923 K has been confirmed. Powders annealed for 1 h at temperatures of 1123 K and 1223 K were partially recrystallised and contained high number densities ( N V > 10 23 m −3 ) of coherent 2 nm yttrium–aluminium–oxygen rich nano-particles. The identification of particle free zones in recrystallised grains, adjacent to recrystallising interfaces, plus the identical orientation relationships between nano-particles and the matrices in both unrecrystallised and recrystallised grains, indicates that the Y–Al–O nano-particles, first formed in fine grained regions, are dissolved during recrystallisation and re-precipitated subsequently in recrystallised grains.

Many layered materials can be cleaved down to individual atomic planes, similar to graphene, but only a small minority of them are stable under ambient conditions. The rest reacts and decomposes in air, which has severely hindered their investigation and possible uses. Here we introduce a remedial approach based on cleavage, transfer, alignment and encapsulation of air-sensitive crystals, all inside a controlled inert atmosphere. To illustrate the technology, we choose two archetypal two-dimensional crystals unstable in air: black phosphorus and niobium diselenide. Our field-effect devices made from their monolayers are conductive and fully stable under ambient conditions, in contrast to the counterparts processed in air. NbSe2 remains superconducting down to the monolayer thickness. Starting with a trilayer, phosphorene devices reach sufficiently high mobilities to exhibit Landau quantization. The approach offers a venue to significantly expand the range of experimentally accessible two-dimensional crystals and their heterostructures., Comment: 4 figures

The surface oxidation of aluminum is still poorly understood despite its vital role as an insulator in electronics, in aluminum-air batteries, and in protecting the metal against corrosion. Here we use atomic resolution imaging in an environmental transmission electron microscope (TEM) to investigate the mechanism of aluminum oxide formation. Harnessing electron beam sputtering we prepare a pristine, oxide-free metal surface in the TEM. This allows us to study, as a function of crystallographic orientation and oxygen gas pressure, the full oxide growth regime from the first oxide nucleation to a complete saturated, few-nanometers-thick surface film.

Copper nanoparticles (Cu-NPs) have a wide range of applications as heterogeneous catalysts. In this study, a novel green biosynthesis route for producing Cu-NPs using the metal-reducing bacterium, Shewanella oneidensis is demonstrated. Thin section transmission electron microscopy shows that the Cu-NPs are predominantly intracellular and present in a typical size range of 20-40 nm. Serial block-face scanning electron microscopy demonstrates the Cu-NPs are well-dispersed across the 3D structure of the cells. X-ray absorption near-edge spectroscopy and extended X-ray absorption fine-structure spectroscopy analysis show the nanoparticles are Cu(0), however, atomic resolution images and electron energy loss spectroscopy suggest partial oxidation of the surface layer to Cu

Transformation products of two-line ferrihydrite associated with Lu(III) were studied after 12 years of aging using aberration-corrected high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), high-efficiency energy-dispersive X-ray spectroscopy (EDXS), and density functional theory (DFT). The transformation products consisted of hematite nanoparticles with overgrown goethite needles. High-efficiency STEM-EDXS revealed that Lu is only associated with goethite needles, and atomic-resolution HAADF-STEM reveals structural incorporation of Lu within goethite, partially replacing structural Fe sites. This finding corroborates those recently obtained by AsFlFFF and EXAFS spectroscopy on the same sample (Finck et al. 2018). DFT calculations indicate that Lu incorporation within goethite or hematite are almost equally likely, suggesting that experimental parameters such as temperature and reaction time which affect reaction kinetics, play important roles in determining the Lu uptake. It seems likely that these results may be transferable to predict the behavior of chemically homologous trivalent actinides.

Precipitation hardening is one of the dominant strengthening mechanisms for Mg alloys, especially for Mg alloys containing rare earth elements. However, precipitation hardening of conventional Mg alloys (such as AZ91D, ZK60 or even WE54/43) is relatively weaker than in high performance Al alloys [such as Al–Cu–Mg based alloys (2024) and Al–Zn–Mg–Cu based alloys (7075, 7050)]. Further avenues for improving precipitation hardening of Mg alloy are therefore being actively explored. In this paper, co-precipitation on the basal and prismatic planes of the α-Mg matrix in a Mg–2.4Gd–0.4Ag–0.1Zr alloy after over-ageing at 200 °C for 2048 h was investigated using high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) imaging and electron energy loss spectroscopy (EELS). Ag was observed within precipitates on the basal plane, while Gd was observed within precipitates on both the basal and prismatic planes. Furthermore, Ag, Gd-rich clusters were also observed in the vicinity of these precipitates, which were proposed to form during solution treatment and to coarsen during subsequent ageing treatment.

A novel, solution-based route to biocompatible, cysteine-capped gold-zinc telluride (Au-ZnTe) core-shell nanoparticles with potential in biomedical applications is described. The optical properties of the core-shell nanoparticles show combined beneficial features of the individual parent components. The tunable emission properties of the semiconductor shell render the system useful for imaging and biological labeling applications. Powder X-ray diffraction analysis reveals the particles contain crystalline Au and ZnTe. Transmission electron microscope (TEM) imaging of the particles indicates they are largely spherical with sizes in the order of 2-10 nm. Elemental mapping using X-ray energy dispersive spectroscopy (XEDS) in the scanning transmission electron microscope (STEM) mode supports a core-shell morphology. The biocompatibility and cytotoxicity of the core-shells was investigated on a human pancreas adenocarcinoma (PL45) cell line using the WST-1 cell viability assay. The results showed that the core-shells had no adverse effects on the PL45 cellular proliferation or morphology. TEM imaging of PL45 cell cross sections confirmed the cellular uptake and isolation of the core-shell nanoparticles within the cytoplasm via membrane interactions. The fluorescence properties of the Au-ZnTe core-shell structures within the PL45 cell lines results confirmed their bio-imaging potential. The importance and novelty of this research lies in the combination of gold and zinc telluride used to produce a water soluble, biocompatible nanomaterial which may be exploited for drug delivery applications within the domain of oncology.

Gas permeation through nanoscale pores is ubiquitous in nature and has an important role in many technologies 1,2. Because the pore size is typically smaller than the mean free path of gas molecules, the flow of the gas molecules is conventionally described by Knudsen theory, which assumes diffuse reflection (random-angle scattering) at confining walls 3,4,5,6,7. This assumption holds surprisingly well in experiments, with only a few cases of partially specular (mirror-like) reflection known 5,8,9,10,11. Here we report gas transport through ångström-scale channels with atomically flat walls 12,13 and show that surface scattering can be either diffuse or specular, depending on the fine details of the atomic landscape of the surface, and that quantum effects contribute to the specularity at room temperature. The channels, made from graphene or boron nitride, allow helium gas flow that is orders of magnitude faster than expected from theory. This is explained by specular surface scattering, which leads to ballistic transport and frictionless gas flow. Similar channels, but with molybdenum disulfide walls, exhibit much slower permeation that remains well described by Knudsen diffusion. We attribute the difference to the larger atomic corrugations at molybdenum disulfide surfaces, which are similar in height to the size of the atoms being transported and their de Broglie wavelength. The importance of this matter-wave contribution is corroborated by the observation of a reversed isotope effect, whereby the mass flow of hydrogen is notably higher than that of deuterium, in contrast to the relation expected for classical flows. Our results provide insights into the atomistic details of molecular permeation, which previously could be accessed only in simulations 10,14, and demonstrate the possibility of studying gas transport under controlled confinement comparable in size to the quantum-mechanical size of atoms.

Remote plasma sputtering (RPS) offers a high degree of control over the sputtering parameters used to deposit thin metallic films and has demonstrated a capability to control the media grain size distribution. Narrow grain size distributions remain a key requirement for future magnetic media. Here we report a comprehensive magnetometry, X-ray diffraction and transmission electron microscopy study of how RPS affects the grain size distribution of continuous, non-segregated L1 0 FePt thin films. These provide a model medium for heat-assisted magnetic recording and more generally for spintronic devices such as magnetoresistive random access memory and spin torque oscillators, where very high perpendicular magnetocrystalline anisotropy is required. Varying the target DC bias voltage, which in RPS can be tuned independently of the plasma generation, produces no meaningful, statistical change in average grain size, 6.5 ± 0.1 nm, for as-deposited, disordered FePt. Annealing at 800 °C creates the well-ordered L1 0 phase but results in an increased average grain size of 8.3–13.6 nm, and a significantly wider grain size distribution of 6.4–8.5 nm. These results show that whilst RPS is capable of producing well-ordered L1 0 FePt thin films, it does not offer an advantage in controlling the grain size of FePt, as reported in other thin film systems.

Two novel automated methods for the determination of surface roughness and chemical distribution in individual nanoparticles are presented and applied to nanoparticles synthesised by the galvanic replacement reaction. The two methodologies apply the determination of circumferential and radial line profiles to determine surface roughness and elemental distribution respectively. The surface roughness analysis provides details on localised changes in roughness in comparison to single measures of circularity. The X-ray spectroscopic concentric ring scan outperforms conventional line scans when elemental distribution approximately possesses a spherical symmetry.

Laminar membranes of two-dimensional materials are excellent candidates for applications in water filtration due to the formation of nanocapillaries between individual crystals that can exhibit a molecular and ionic sieving effect, while allowing high water flux. This approach has been exemplified previously with graphene oxide, however these membranes suffer from swelling when exposed to liquid water, leading to low salt rejection and reducing their applicability for desalination applications. Here, we demonstrate that by producing thin (∼5 μm) laminar membranes of exfoliated molybdenum disulfide (MoS

The molecular precursors [Mo(S2CNEt2)4] (1), [Re(S2CC6H5)(S3CC6H5)2] (2), and [Re2(μ-S)2(S2CNEt2)4] (3) were used to deposit thin films of Re-doped MoS2 at 550 °C by aerosol assisted chemical vapour Deposition (AACVD). ICP-OES was used to quantify the amount of Re dopant in each film which range from ca. 2-17 at% Re, with greater incorporation of Re from films using precursor (3). In general, lightly doped films show evidence of elemental homogeneity and retention of structure from EDX spectroscopy mapping and p-XRD measurements. However, Raman spectroscopy suggests that the MoS2 structure is lost upon heavy doping (ca. >4-7 at% Re) by the disappearance of the E2g and A1g optical phonons of MoS2, which we attribute to the introduction of intralayer Re-Re bonding caused by the larger 5d orbitals of Re. Electron microscopy shows that inclusion of Re dopant atoms also dramatically influences the morphology of the films produced, ranging from lamellar structures to clusters and florets, though at similar doping level the morphologies are similar for films made from both Re precursors.

Light emitting semiconducting quantum dots show great promise as solar cells, optoelectronic devices and multimodal imaging probes. Here we demonstrate successful grafting of a thiol-functionalised GdIII MRI contrast agent onto the surface of core-multishell CdSe/CdS/ZnS quantum dots. The resulting nanoprobe exhibits intense photoluminescence and unprecedentedly large T1 relaxivity of 6800 mM−1 s−1 per nanoparticle due to secure implanting of ca. 620 magnetic centers per quantum dot unit.

Solid phase crystallization offers an attractive route to synthesize Ni nanoparticles on a La2O3 support. These materials have shown great promise as catalysts for methane oxidation and similar reactions. Synthesis is achieved by the reduction of a LaNiO3 (LNO) precursor at high temperatures, but the reduction pathway can follow a variety of routes. Optimization of catalytic properties such as the long-term stability has been held back by a lack of understanding of the factors impacting the reduction pathway, and its strong influence on the structure of the resulting Ni/La2O3 catalyst. Here we show the first evidence of the importance of extended structural defects in the LNO precursor material (2D stacking faults and 3D inclusions) for determining the reaction pathway and therefore the properties of the final catalyst. Here we compare the crystallization of LNO nanoparticles via two different pathways using in-situ STEM, in-situ synchrotron XRD, and DFT electronic structure calculations. Control of extended defects is shown to be a key microstructure component for improving catalyst lifetimes.

Vertically stacked van der Waals heterostructures are a lucrative platform for exploring the rich electronic and optoelectronic phenomena in two-dimensional materials. Their performance will be strongly affected by impurities and defects at the interfaces. Here we present the first systematic study of interfaces in van der Waals heterostructure using cross sectional scanning transmission electron microscope (STEM) imaging. By measuring interlayer separations and comparing these to density functional theory (DFT) calculations we find that pristine interfaces exist between hBN and MoS2 or WS2 for stacks prepared by mechanical exfoliation in air. However, for two technologically important transition metal dichalcogenide (TMDC) systems, MoSe2 and WSe2, our measurement of interlayer separations provide the first evidence for impurity species being trapped at buried interfaces with hBN: interfaces which are flat at the nanometer length scale. While decreasing the thickness of encapsulated WSe2 from bulk to monolayer we see a systematic increase in the interlayer separation. We attribute these differences to the thinnest TMDC flakes being flexible and hence able to deform mechanically around a sparse population of protruding interfacial impurities. We show that the air sensitive two dimensional (2D) crystal NbSe2 can be fabricated into heterostructures with pristine interfaces by processing in an inert-gas environment. Finally we find that adopting glove-box transfer significantly improves the quality of interfaces for WSe2 compared to processing in air.

High angle annular dark field scanning transmission electron microscope imaging and electron energy loss spectroscopy was used to elucidate the elemental distribution (Gd, Zn, Mn) within the long-period stacking ordered (LPSO) structure in a Mg-15Gd-0.8Zn-0.8Mn (wt%) alloy. While Gd and Zn enrichment was observed within the LPSO structure, no significant enrichment in Mn was observed. After averaging over a large region, a very weak Mn signal was resolved but no significant variations in Mn signal were observed over this region, suggesting that Mn is indeed present. These results provide useful information to support the future development of high performance Mg alloys.

High angle annular dark field scanning transmission electron microscope (HAADF-STEM) imaging and quantitative energy-dispersive X-ray spectroscopy (EDX) analysis was used to elucidate the Cu segregation on the interface between Al2O3 substrate and Al-1.4Cu alloy. A significant Cu segregation (about 2 at%) was observed, which can be mainly attributed to the enhanced diffusion caused by the high strain between Al2O3 substrate and Al-1.4Cu alloy. This investigation highlights the importance of Cu segregation and subsequent eutectic reaction on the heterogeneous nucleation of Al on Al2O3 substrate.

We have investigated the structure of atomic defects within monolayer NbSe

The constant-voltage electrical stress and 10-keV x-ray irradiation responses of encapsulated graphene-hBN devices are evaluated. Both constant-voltage stress and x-ray exposure induce only modest shifts in the current and the Dirac point of the graphene. Charge trapping at or near the graphene/BN interface is observed after x-ray irradiation. The experimental results suggest that net hole trapping occurs in the BN at low doses and that net electron trapping occurs at higher doses. First-principles calculations also demonstrate that hydrogenated substitutional carbon impurities at B/N sites at or near the graphene/BN interface can play an additional role in the radiation response of these structures.

Barrier-type, nanocrystalline anodic films have been formed on a ZE41 magnesium alloy under a constant current density of 5 mA cm-2 in a glycerol/fluoride electrolyte, containing 5 vol.% of added water, at 293 K. The films contain magnesium, fluorine and oxygen as the major species, and lower amounts of alloying element species. The films grow at an efficiency of ∼0.8 to 0.9, with a formation ratio in the range of ∼1.2 to 1.4 nm V -1 at the matrix regions and with a ratio of ∼1.8 nm V -1 at Mg-Zn-RE second phase. At the former regions, rare earth species are enriched at the film surface and zinc is enriched in the alloy. A carbon- and oxygen-rich band within the film suggests that the films grow at the metal/film and film/electrolyte interfaces. © 2014 The Authors. Published by Elsevier Ltd.

Coccolithophores create an intricate exoskeleton from nanoscale calcite platelets. Shape, size, and crystal orientation are controlled to a remarkable degree. In this study, the structure of Rhabdosphaera clavigera is described in detail for the first time through a combination of electron microscopy techniques, including three-dimensional electron tomography. The coccolithophore exhibits several micrometer long 5-fold symmetric spines with diameters of approximately 0.5 μm. The nanorystals constituting the spine are arranged radially along the longitudinal axis, protruding from the almost flat disks that form the coccosphere. The stem of the spine is shown to consist of {104} calcite rhombohedra single crystalline platelets, arranged in five separate spiral “staircases”. The spine tip shows 15 structural elements: five large “panels” protruding outward along the lateral plane and five leaf-shaped smaller units which form the topmost steps of the staircases. The outer tip consists of five long thin platel...

Graphitic materials and graphite composites experience dimensional change when exposed to\ud radiation-induced atomic displacements. This has major implications for current and future\ud technological ranging from nuclear fission reactors to the processing of graphene-silicon\ud hybrid devices. Dimensional change in nuclear graphites is a complex problem involving the\ud filler, binder, porosity, cracks and atomic-level effects all interacting within the polygranular\ud structure. An improved understanding of the atomistic mechanisms which drive dimensional\ud change within individual graphitic crystals is required to feed into the multiscale modelling of\ud this system.\ud In this study, micromechanically exfoliated samples of highly oriented pyrolytic graphite\ud have been ion irradiated and studied in situ using transmission electron microscopy (TEM) in\ud order to gain insights into the response of single graphitic crystals to displacing radiation.\ud Under continuous ion bombardment, a complex dynamic sequence of deformation evolves\ud featuring several distinct stages from the inducement of strain, the creation of dislocations\ud leading to dislocation arrays, the formation of kink band networks and localised doming of the sample. Observing these ion irradiation-induced processes using in situ TEM reveals\ud previously unknown details of the sequence of microstructural developments and physics\ud driving these phenomena. A mechanistic model consistent with the microstructural changes\ud observed is presented.

The use of analytical spectroscopies during scanning/transmission electron microscope (S/TEM) investigations of micro- and nano-scale structures has become a routine technique in the arsenal of tools available to today’s materials researchers. Essential to implementation and successful application of spectroscopy to characterization is the integration of numerous technologies, which include electron optics, specimen holders, and associated detectors. While this combination has been achieved in many instrument configurations, the integration of X-ray energy-dispersive spectroscopy and in situ liquid environmental cells in the S/TEM has to date been elusive. In this work we present the successful incorporation/modifications to a system that achieves this functionality for analytical electron microscopy.

The effects of displacing radiation in graphitic materials are important for technologies including nuclear power, graphitic-based nanocomposites and hybrid graphene–silicon high-speed integrated electronics. These applications expose graphitic materials to displacing irradiation either during manufacture and/or involve the deployment of these materials into irradiating environments. One of the most interesting phenomena in the response of graphite to irradiation is the formation of kink bands on the surface of the material. Here we apply the technique of transmission electron microscopy with in situ ion irradiation to observe the dynamic formation of these features. Kink bands were created at both 100 and 298 K with doming of the samples also observed due to radiation induced dimensional change leading to mechanical deformation. Probably at 298 K, but certainly at 100 K, there should be no point defect mobility in graphite according to the latest theoretical calculations. However, some of the theories of dimensional change in graphite require point defect motion and agglomeration in order to operate. The implications of the experimental results for existing theories and the possibility of thermal effects due to the ion irradiation are discussed.

A new design of in situ liquid cells is demonstrated, providing the first nanometer resolution elemental mapping of nanostructures in solution. The technique has been applied to investigate dynamic liquid-phase synthesis of core-shell nanostructures and to simultaneously image the compositional distribution for multiple elements within the resulting materials.

Organophilic mixed matrix membranes (MMMs) have been fabricated with the polymer of intrinsic microporosity PIM-1 and graphene oxide (GO) derivatives for the recovery of 1-butanol and ethanol from aqueous solutions via pervaporation (PV). Graphene oxide (GO) has been synthesized in solution through a modified Hummers’ method, functionalized with alkylamines, and further reduced. The use of two alkylamines with chains of different lengths, octylamine (OA) and octadecylamine (ODA) −8 and 18 carbons, respectively - has been evaluated and the functionalized GO materials have been used as fillers in MMMs. The membranes have been prepared by casting-solvent evaporation of PIM-1/GO derivative solutions at room temperature, and a range of characterization techniques have been used to interpret their structure and relate it to their separation performance. Electron microscopy has been carried out to determine the morphology of the membranes and the dispersion of the functionalized GO flakes in the polymer matrix. Moreover, the membranes have been characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and contact angle. Separation of alcohol from two binary mixtures composed of ethanol (EtOH)/water and butanol (BtOH)/water, containing 5 wt% of alcohol, have been performed. Under these conditions, the incorporation of graphene-like fillers at relatively low concentrations shows an increase in average separation factor for butanol (βBtOH/H2O) from 13.5 for pure PIM-1 membranes to, in some cases, more than double for the MMMs; with the addition of 0.1 wt% of reduced amine-functionalized GO βBtOH/H2O reaches 32.9 and 26.9 for the short-chain (OA) and the long-chain (ODA) alkylamines, respectively.

Plasmon-induced phenomena have recently attracted considerable attention. At the same time, relatively little research has been conducted on electrochemistry mediated by plasmon excitations. Here we report plasmon-induced formation of nanoscale quantized conductance filaments within metal-insulator-metal heterostructures. Plasmon-enhanced electromagnetic fields in an array of gold nanodots provide a straightforward means of forming conductive CrOx bridges across a thin native chromium oxide barrier between the nanodots and an underlying metallic Cr layer. The existence of these nanoscale conducting filaments is verified by transmission electron microscopy and contact resistance measurements. Their conductance was interrogated optically, revealing quantised relative transmission of light through the heterostructures across a wavelength range of 1–12 μm. Such plasmon-induced electrochemical processes open up new possibilities for the development of scalable devices governed by light.

Ion permeation and selectivity of graphene oxide membranes with sub-nm channels dramatically alters with the change in interlayer distance due to dehydration effects whereas permeation of water molecules remains largely unaffected. Graphene oxide membranes show exceptional molecular permeation properties, with promise for many applications1,2,3,4,5. However, their use in ion sieving and desalination technologies is limited by a permeation cutoff of ∼9 A (ref. 4), which is larger than the diameters of hydrated ions of common salts4,6. The cutoff is determined by the interlayer spacing (d) of ∼13.5 A, typical for graphene oxide laminates that swell in water2,4. Achieving smaller d for the laminates immersed in water has proved to be a challenge. Here, we describe how to control d by physical confinement and achieve accurate and tunable ion sieving. Membranes with d from ∼9.8 A to 6.4 A are demonstrated, providing a sieve size smaller than the diameters of hydrated ions. In this regime, ion permeation is found to be thermally activated with energy barriers of ∼10–100 kJ mol–1 depending on d. Importantly, permeation rates decrease exponentially with decreasing sieve size but water transport is weakly affected (by a factor of

Understanding how two-dimensional (2D) nanomaterials interact with the biological milieu is fundamental for their development toward biomedical applications. When thin, individualized graphene oxide (GO) sheets were administered intravenously in mice, extensive urinary excretion was observed, indicating rapid transit across the glomerular filtration barrier (GFB). A detailed analysis of kidney function, histopathology, and ultrastructure was performed, along with the in vitro responses of two highly specialized GFB cells (glomerular endothelial cells and podocytes) following exposure to GO. We investigated whether these cells preserved their unique barrier function at doses 100 times greater than the dose expected to reach the GFB in vivo. Both serum and urine analyses revealed that there was no impairment of kidney function up to 1 month after injection of GO at escalating doses. Histological examination suggested no damage to the glomerular and tubular regions of the kidneys. Ultrastructural analysis by transmission electron microscopy showed absence of damage, with no change in the size of podocyte slits, endothelial cell fenestra, or the glomerular basement membrane width. The endothelial and podocyte cell cultures regained their full barrier function after >48 h of GO exposure, and cellular uptake was significant in both cell types after 24 h. This study provided a previously unreported understanding of the interaction between thin GO sheets with different components of the GFB in vitro and in vivo to highlight that the glomerular excretion of significant amounts of GO did not induce any signs of acute nephrotoxicity or glomerular barrier dysfunction. journal article 2016 Dec 27 2016 12 12 imported

Tilted illumination exit-wave restoration is compared for two aberration-corrected instruments at different accelerating voltages. The experimental progress of this technique is also reviewed and the significance of off-axial aberrations examined. Finally, the importance of higher order aberration compensation combined with careful correction of the lower order aberrations is highlighted.

Magnesium diboride superconducting wires and bulk samples synthesized at high pressure have been produced with a variety of reactive metal additions. All these samples showed high critical current densities, but here we are most interested in the striking result that reactive metal additions such as titanium substantially improved the critical current values, but had little detrimental effect on Tc values. For instance, the critical current values in the wires could be increased by more than a factor of 3.5 at 4 K and 10 T by the inclusion of up to 10 wt% of Ti. In bulk materials the J c values can be increased by even larger values, and the irreversibility field at 20 K increased to above 7 T. In a detailed study of the microstructure of these materials we have shown that PIT ex situ wires with 10 wt% titanium additions have a complicated layered microstructure around the Ti-rich particles, possibly forming titanium-boron phases, but also incorporating impurity elements including hydrogen. X-ray diffraction data, TEM and elemental mapping in the NanoSIMS confirmed the surprising suggestion that samples synthesized at high pressure from Mg and B with Ti additions contain a titanium hydride. These new compositional data support the idea that reactive metal additions are extremely beneficial in MgB2 wires and bulk materials because they preferentially adsorb deleterious impurities from the superconducting matrix. © 2005 IOP Publishing Ltd.

Transmission electron microscopy is an extremely powerful technique for direct characterization of local structure at the atomic scale. However, the resolution of this technique is fundamentally limited by the partial coherence of the electron beam. In this Letter we demonstrate a method that extends the ultimate resolution of the latest generation of aberration corrected transmission electron microscopes by 41% relative to that achievable using conventional axial imaging. Experimental results verify that a real space resolution of 78 pm has been achieved at 200 kV.

A wide variety of powders, including Nb, Ti, Zr, Hf and W, metal oxides like Nb2O5, Ti2O5, V2O5 and other compounds like SiC, SrCO3 and boron nitride, have all been used at the 10 wt% level as additions into commercial MgB2 powder for the fabrication of single-core, ex situ wires using groove and two-axial rolling deformation and final heat treatment at 950 °C /0.5 h in Ar. Transport current measurements have shown that metal particle addition leads to an especially significant improvement in current carrying capacity. The presence of normal particles influences both the resistivity and also the thermal conductivity of the MgB2 core, and the improved internal stability may be responsible for the increased critical current values. This observation may be very important for future development of practical MgB2 composite superconducting wires.

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Transmission electron microscope (TEM) images recorded under tilted illumination conditions transfer higher spatial frequencies than axial images. This super resolution information transfer is highly directional in a single image, but can be extended in all directions through the use of complementary beam tilts during exit wave function reconstruction. We have determined the optimal experimental tilt magnitude for aperture synthesis in an aberration-corrected TEM. It is shown that electron-optical aberration correction allows the use of larger tilt angles and reduces the constraints that are imposed on experimental data acquisition in an uncorrected microscope. We demonstrate that, in many cases, the resolution improvement achievable is now limited by the sample and not by instrumental parameters. An exit wave function is presented that has been successfully reconstructed from a dataset of aberration-corrected images, including images acquired at a beam tilt of 18 mrad, which clearly demonstrates a resolution improvement from 0.11 nm to better than 0.08 nm at 200 kV.

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Bottom-up (aerosol-assisted chemical vapor deposition, AACVD) and top-down (liquid phase exfoliation, LPE) processing methodologies are used in tandem to produce colloids of few-layer thick rhenium disulfide (ReS2) in N-methyl pyrrolidone. The processing route we use is a potentially robust and scalable pathway to manufacture useful 2D materials.

A new method to perform X-ray absorption correction for spherical particles in quantitative energy-dispersive X-ray spectroscopy in the scanning transmission electron microscope is presented. An absorption correction factor is derived and simulated data is presented encompassing a range of X-ray absorption conditions. Theoretical calculations are compared with experimental data of X-ray counts from Au nanoparticles to verify the derived methodology. The effect of detector elevation angle is considered and a comparison with thin-film absorption correction is included.

Scientific Reports 6: Article number: 20480; 10.1038/srep20480 published online: February092016; updated: March042016. The Acknowledgements section in this Article is incomplete. “S.J.H. and E.A.L. acknowledge funding from the Engineering and Physical Sciences Research Council (EPSRC) UK Grants EP/G035954/1 and EP/J021172/1 and from the Defence Threat Reduction Agency Grant HDTRA1-12-1-0013. E.A.L. would like to thank the North West Nanoscience Doctoral Training Centre (NOWNano DTC) for supporting his studentship. The authors wish to acknowledge the support from H.M. Government (UK) for the provision of the funds for the FEI Titan G2 80-200 S/TEM associated with research capability of the Nuclear Advanced Manufacturing Research Centre.” should read: “S.J.H. and E.A.L. acknowledge funding from the Engineering and Physical Sciences Research Council (EPSRC) UK Grants EP/G035954/1 and EP/J021172/1 and from the Defence Threat Reduction Agency Grant HDTRA1-12-1-0013. E.A.L. would like to thank the North West Nanoscience Doctoral Training Centre (NOWNano DTC) for supporting his studentship. The authors wish to acknowledge the support from H.M. Government (UK) for the provision of the funds for the FEI Titan G2 80-200 S/TEM associated with research capability of the Nuclear Advanced Manufacturing Research Centre. Open access for this article was funded by King’s College London.”

High-resolution 2D and 3D electron microscopy have been employed to investigate the dealloying of S phase (Al 2 CuMg) particles in an AA 2024-T3 aluminium alloy. Preferential dissolution of magnesium and aluminium produced a sponge-like remnant with nanosize porosity and a copper-rich remnant network. The dealloyed S phase remnant retains a tetragonal structure with a smaller lattice parameter than the S phase. Metallic copper nanoparticles, constituting 4–8% of the dealloyed remnant, are present at the intersections of remnant branches. At the surface of the remnant, a copper layer of ∼2 nm thickness is formed, which terminates further dissolution of the less noble elements.