A5047363695- Electron and X-Ray Spectroscopy Techniques
- Advanced Electron Microscopy Techniques and Applications
- Electronic and Structural Properties of Oxides
- Graphene research and applications
- Magnetic and transport properties of perovskites and related materials
- Semiconductor materials and devices
- Advanced Materials Characterization Techniques
- Ferroelectric and Piezoelectric Materials
- Multiferroics and related materials
- Advanced Thermoelectric Materials and Devices
- Quantum Dots Synthesis And Properties
- Nanowire Synthesis and Applications
- Chalcogenide Semiconductor Thin Films
- 2D Materials and Applications
- Machine Learning in Materials Science
- Magnetic properties of thin films
- Electrocatalysts for Energy Conversion
- Aluminum Alloy Microstructure Properties
- Catalytic Processes in Materials Science
- Aluminum Alloys Composites Properties
- Integrated Circuits and Semiconductor Failure Analysis
- Gold and Silver Nanoparticles Synthesis and Applications
- Advanced Condensed Matter Physics
- Force Microscopy Techniques and Applications
- Surface and Thin Film Phenomena
Sci-Tech Daresbury
2016-2025
University of Leeds
2018-2025
SuperSTEM
2015-2024
Daresbury Laboratory
2014-2023
Durham University
2022
University of Glasgow
2022
Natural History Museum
2022
University of York
2022
Centre National de la Recherche Scientifique
2022
Aix-Marseille Université
2022
Few layer black phosphorus is a new two-dimensional material which of great interest for applications, mainly in electronics. However, its lack stability severely limits our ability to synthesise and process this material. Here we demonstrate that high-quality, few-layer nanosheets can be produced large quantities by liquid phase exfoliation the solvent N-cyclohexyl-2-pyrrolidone (CHP). We control nanosheet dimensions have developed metrics estimate both size thickness spectroscopically....
We report the formation of a novel ferromagnetic state in antiferromagnet ${\mathrm{BiFeO}}_{3}$ at interface with ferromagnet ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$. Using x-ray magnetic circular dichroism Mn and Fe ${L}_{2,3}$ edges, we discovered that development this spin structure is strongly associated onset significant exchange bias. Our results demonstrate directly related to an electronic orbital reconstruction interface, which supported by linearly polarized...
Graphitic carbon nitride (g‐C 3 N 4 ) exhibits unique properties as a support for single‐atom heterogeneous catalysts (SAHCs). Understanding how the synthesis method, carrier properties, and metal identity impact isolation of centers is essential to guide their design. This study compares effectiveness direct postsynthetic routes prepare SAHCs by incorporating palladium, silver, iridium, platinum, or gold in g‐C distinct morphology (bulk, mesoporous exfoliated). The speciation (single atoms,...
Formic acid is a valuable chemical derived from biomass, as it has high hydrogen-storage capacity and appears to be an attractive source of hydrogen for various applications. Hydrogen production via formic decomposition often based on using supported catalysts with Pt-group metal nanoparticles. In the present paper, we show that proceeds more rapidly single atoms (by up 1 order magnitude). These can obtained by rather simple means through anchoring metals onto mesoporous N-functionalized...
The ability of electron microscopes to analyze all the atoms in individual nanostructures is limited by lens aberrations. However, recent advances aberration-correcting optics have led greatly enhanced instrument performance and new techniques microscopy. development an ultrastable microscope with a monochromated high-brightness source has significantly improved resolution contrast. In present work, we report information transfer beyond 50 pm show images single gold signal-to-noise ratio as...
Recent dramatic progress in studying various two-dimensional (2D) atomic crystals and their heterostructures calls for better more detailed understanding of crystallography, reconstruction, stacking order, etc. For this, direct imaging identification each every atom is essential. Transmission electron microscopy (TEM) scanning transmission (STEM) are ideal perhaps the only tools such studies. However, beam can some cases induce structure changes, radiation damage becomes an obstacle...
The control of material interfaces at the atomic level has led to novel interfacial properties and functionalities. In particular, study polar discontinuities between complex oxides lies frontier modern condensed matter research. Here we employ a combination experimental measurements theoretical calculations demonstrate bulk property, namely ferroelectric polarization, heteroepitaxial bilayer by precise atomic-scale interface engineering. More specifically, is achieved exploiting valence...
Nanoholes, etched under an electron beam at room temperature in single-layer graphene sheets as a result of their interaction with metal impurities, are shown to heal spontaneously by filling up either nonhexagon, graphene-like, or perfect hexagon 2D structures. Scanning transmission microscopy was employed capture the healing process and study atom-by-atom regrown structure. A combination these nanoscale etching reknitting processes could lead new tailoring approaches.
Atoms on the edge: The atomic edge structure of industrial-style MoS2 nanocatalysts was imaged using single-atom sensitive electron microscopy (see picture). observed terminations match predictions model catalyst studies and thus address so-called "materials gap" in catalysis.
Here, we demonstrate the production of large quantities gallium sulfide (GaS) nanosheets by liquid exfoliation layered GaS powder. The was achieved sonication powder in suitable solvents. variation dispersed concentration with solvent consistent classical solution thermodynamics and showed successful solvents to be those Hildebrand solubility parameters close 21.5 MPa1/2. In this way, could produced at concentrations up ∼0.2 mg/mL lateral sizes thicknesses 50–1000 nm 3–80 layers,...
Atom-thin transition metal dichalcogenides (TMDs) have emerged as fascinating materials and key structures for electrocatalysis. So far, their edges, dopant heteroatoms defects been intensively explored active sites the hydrogen evolution reaction (HER) to split water. However, grain boundaries (GBs), a type of in TMDs, overlooked due low density large structural variations. Here, we demonstrate synthesis wafer-size atom-thin TMD films with an ultra-high-density GBs, up ~1012 cm-2. We...
A combination of scanning transmission electron microscopy, energy loss spectroscopy, and ab initio calculations reveal striking electronic structure differences between two distinct single substitutional Si defect geometries in graphene. Optimised acquisition conditions allow for exceptional signal-to-noise levels the spectroscopic data. The near-edge fine can be compared with great accuracy to simulations either an sp(3)-like configuration a trivalent or more complicated hybridized...
Seeing single silicon atom vibrations Vibrational spectroscopy can achieve high energy resolution, but spatial resolution of unperturbed is more difficult to realize. Hage et al. show that a single-atom impurity in solid (a graphene) give rise distinctive localized vibrational signatures. They used high-resolution electron energy-loss scanning transmission microscope detect this signal. An experimental geometry was chosen reduced the relative elastic scattering contribution, and repeated...
Although Li- and Mn-rich transition metal oxides have been extensively studied as high-capacity cathode materials for Li-ion batteries, the crystal structure of these in their pristine state is not yet fully understood. Here we apply complementary electron microscopy spectroscopy techniques at multi-length scale on well-formed Li1.2(Ni0.13Mn0.54Co0.13)O2 crystals with two different morphologies well commercially available similar compositions, unambiguously describe structural make-up...
Doping of graphene via low energy ion implantation could open possibilities for fabrication nanometer-scale patterned graphene-based devices as well functionalization compatible with large-scale integrated semiconductor technology. Using advanced electron microscopy/spectroscopy methods, we show the first time directly that can be doped B and N retention is in good agreement predictions from calculation-based literature values. Atomic resolution high-angle dark field imaging (HAADF) combined...
Distributions and atomic sites of transition metals gold on suspended graphene were investigated via high-resolution scanning transmission electron microscopy, especially using resolution high angle dark field imaging. All metals, albeit as singular atoms or atom aggregates, reside in the omni-present hydrocarbon surface contamination; they do not form continuous films, but clusters nanocrystals. No interaction was found between Au clean single-layer surfaces, i.e., no are retained such...
We demonstrate that 60-keV electron irradiation drives the diffusion of threefold-coordinated Si dopants in graphene by one lattice site at a time. First principles simulations reveal each step is caused an impact on C atom next to dopant. Although atomic motion happens below our experimental time resolution, stochastic analysis 38 such jumps reveals probability for their occurrence good agreement with simulations. Conversions from three- fourfold coordinated dopant structures and subsequent...
Vibrational modes affect fundamental physical properties such as the conduction of sound and heat can be sensitive to nano- atomic-scale structure. Probing momentum transfer dependence vibrational provides a wealth information about materials system; however, experimental work has been limited essentially bulk averaged surface approaches or small wave vectors. We demonstrate combined theoretical methodology for nanoscale mapping optical acoustic phonons across first Brillouin zone, in...
Abstract The functional properties of transition metal dichalcogenides (TMDs) may be promoted by the inclusion other elements. Here, we studied local stoichiometry single cobalt promoter atoms in an industrial‐style MoS 2 ‐based hydrotreating catalyst. Aberration‐corrected scanning transmission electron microscopy and energy loss spectroscopy show that Co occupy sites at (−100) S edge terminations graphite‐supported nanocrystals Specifically, each atom has four neighboring are arranged a...
Atomic resolution high angle annular dark field imaging of suspended, single-layer graphene, onto which the metals Cr, Ti, Pd, Ni, Al, and Au atoms had been deposited, was carried out in an aberration-corrected scanning transmission electron microscope. In combination with energy loss spectroscopy, employed to identify individual impurity atoms, it shown that nanoscale holes were etched into initiated at sites where single all metal species except for gold come close contact graphene. The...
Advances in source monochromation transmission electron microscopy have opened up new possibilities for investigations of condensed matter using the phonon-loss sector energy-loss spectrum. Here, we explore spatial variations spectrum as an atomic-sized probe is scanned across a thin flake hexagonal boron nitride. We demonstrate that phonon spectral mapping atomic structure possible. These results are consistent with model quantum excitation phonons and confirm Z-contrast imaging based on...
Abstract The structural, chemical, and magnetic properties of magnetite nanoparticles are compared. Aberration corrected scanning transmission electron microscopy reveals the prevalence antiphase boundaries in that have significantly reduced magnetization, relative to bulk. Atomistic modelling with without these defects origin moment. Strong antiferromagnetic interactions across support multiple domains even particles as small 12–14 nm.