A5054268741- Advancements in Battery Materials
- X-ray Diffraction in Crystallography
- Metal and Thin Film Mechanics
- Advanced Battery Materials and Technologies
- Diamond and Carbon-based Materials Research
- High-pressure geophysics and materials
- Graphene research and applications
- Extraction and Separation Processes
- MXene and MAX Phase Materials
- Ferroelectric and Piezoelectric Materials
- Semiconductor materials and devices
- Inorganic Chemistry and Materials
- Semiconductor materials and interfaces
- Ion-surface interactions and analysis
- Advanced ceramic materials synthesis
- Carbon Nanotubes in Composites
- Magnetic Properties and Synthesis of Ferrites
- ZnO doping and properties
- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Nuclear materials and radiation effects
- Magnetic and transport properties of perovskites and related materials
- Transition Metal Oxide Nanomaterials
- Boron and Carbon Nanomaterials Research
- Intermetallics and Advanced Alloy Properties
Helmholtz-Zentrum Dresden-Rossendorf
2014-2025
European X-Ray Free-Electron Laser
2023-2024
European Synchrotron Radiation Facility
2012-2014
University of Cambridge
2011-2014
Institute of Radiation Physics
2012
Universidad San Pablo CEU
2012
Université Joseph Fourier
2011
Centre National de la Recherche Scientifique
2011
Institut Néel
2011
European Science Foundation
2011
Low-temperature (∼450 °C), scalable chemical vapor deposition of predominantly monolayer (74%) graphene films with an average D/G peak ratio 0.24 and domain sizes in excess 220 μm2 is demonstrated via the design alloy catalysts. The admixture Au to polycrystalline Ni allows a controlled decrease nucleation density, highlighting role step edges. In situ, time-, depth-resolved X-ray photoelectron spectroscopy diffraction reveal subsurface C species allow coherent model for formation be devised.
Complementary in situ X-ray photoelectron spectroscopy (XPS), diffractometry, and environmental scanning electron microscopy are used to fingerprint the entire graphene chemical vapor deposition process on technologically important polycrystalline Cu catalysts address current lack of understanding underlying fundamental growth mechanisms catalyst interactions. Graphene forms directly metallic during high-temperature hydrocarbon exposure, whereby an upshift binding energies corresponding C1s...
Using a combination of complementary in situ X-ray photoelectron spectroscopy and diffraction, we study the fundamental mechanisms underlying chemical vapor deposition (CVD) hexagonal boron nitride (h-BN) on polycrystalline Cu. The nucleation growth h-BN layers is found to occur isothermally, i.e., at constant elevated temperature, Cu surface during exposure borazine. A lattice expansion borazine B precipitation from upon cooling highlight that incorporated into bulk, not just...
In situ synchrotron diffraction revealed a stepwise appearance of two new phases upon electrochemical lithium extraction from LiCoPO4. These were demonstrated to have the same olivine-like structure as pristine compound. The lithium-deficient proposed be Li0.7CoPO4 and CoPO4. completely delithiated phase appears unstable in air undergoes amorphization. transitions are reversible, but slow kinetics initial delithiation was identified by potentiostatic intermittent titration technique. We that...
We study the Fe-catalyzed chemical vapor deposition of carbon nanotubes by complementary in situ grazing-incidence X-ray diffraction, reflectivity, and environmental transmission electron microscopy. find that typical oxide supported Fe catalyst films form widely varying mixtures bcc fcc phased nanoparticles upon reduction, which we ascribe to variations minor commonly present contamination levels. Depending on as-formed phase composition, different growth modes occur hydrocarbon exposure:...
A quantitative analysis of in situ and operando X-ray diffraction studies allows for deeper insight into the mechanism Li2S formation consumption. two-step reaction process is proposed both discharge charge. Changing selectivity estimated, with solely being formed during earliest step, followed by possible concurrent Li2S2 intermediate further step discharge.
The scalable chemical vapor deposition of monolayer hexagonal boron nitride (h-BN) single crystals, with lateral dimensions ∼0.3 mm, and continuous h-BN films large domain sizes (>25 μm) is demonstrated via an admixture Si to Fe catalyst films. A simple thin-film Fe/SiO2/Si system used show that controlled diffusion into the allows exclusive nucleation very low densities upon exposure undiluted borazine. Our systematic in situ ex characterization this establishes a basis for further rational...
Highly controlled Fe-catalyzed growth of monolayer hexagonal boron nitride (h-BN) films is demonstrated by the dissolution nitrogen into catalyst bulk via NH3 exposure prior to actual step. This “pre-filling” reservoir allows us control and limit uptake B N species during borazine thereby incubation time h-BN kinetics while also limiting contribution uncontrolled precipitation-driven cooling. Using in situ X-ray diffraction photoelectron spectroscopy combined with systematic calibrations, we...
Carbon diffusion barriers are introduced as a general and simple method to prevent premature carbon dissolution thereby significantly improve graphene formation from the catalytic transformation of solid sources. A thin Al2O3 barrier inserted into an amorphous-C/Ni bilayer stack is demonstrated enable growth uniform monolayer at 600 °C with domain sizes exceeding 50 μm, average Raman D/G ratio <0.07. detailed rationale established via in situ measurements, relevant solid-state wide range...
Nanocomposite thin films comprised of metastable metal carbides in a carbon matrix have wide variety applications ranging from hard coatings to magnetics and energy storage conversion. While their deposition using nonequilibrium techniques is established, the understanding dynamic evolution such nanocomposites under thermal equilibrium conditions at elevated temperatures during processing device operation remains limited. Here, we investigate sputter-deposited nickel carbide (Ni3C)...
The European XFEL delivers up to 27000 intense (>10 12 photons) pulses per second, of ultrashort (≤50 fs) and transversely coherent X-ray radiation, at a maximum repetition rate 4.5 MHz. Its unique beam parameters enable groundbreaking experiments in matter extreme conditions the High Energy Density (HED) scientific instrument. performance HED instrument during its first two years operation, remit, as well ongoing installations towards full operation are presented. Scientific goals...
The synchrotron powder diffraction beamline B2 at HASYLAB/DESY is described. capable of high-resolution as well time-resolved studies and offers several sophisticated ancillary equipments for special applications. A newly developed image-plate system allows kinetic with good resolution in the minutes range. Numerous sample environments allow various standard applications including structure solution, situ observations under flexible defined conditions. Representative examples are shown these...
The morphology of micrometer-sized β-hematin crystals (synthetic malaria pigment) was determined by TEM images and diffraction, grazing incidence synchrotron X-ray diffraction at the air−water interface. needle-like are bounded sharp {100} {010} side faces, capped {011} and, to a lesser extent, {001} end in agreement with hemozoin (malaria crystals. grown presence 10% chloroquine or quinine took appreciably longer precipitate tended be symmetrically tapered toward both ends needle, due...
Abstract The literature states different compositions (M/B = 1:2 vs. 2:5) and structures for diborides of molybdenum tungsten. Using X‐ray neutron powder diffraction as well energy wavelength dispersive electron microprobe analysis, the Mo/B W/B systems were now reinvestigated. Molybdenum diboride crystallizes a stoichiometric compound Mo 2 B 4 (formerly described 5 ) in space group $R{\bar 3}m$ (No. 166, , b 3.01375(2) Å, c 20.9541(3) Å), non‐stoichiometric MoB 2−x P 6 /mmm 191, 3.043(2)...
How does your graphene grow? In situ X-ray photoelectron spectroscopy and diffraction measurements during chemical vapor deposition on Ni catalyst films show that forms both isothermally by precipitation cooling (see picture). A coherent growth model is devised sub-surface dissolved carbon shown to play an important role.
The electrochemical properties of TiO2 with the hollandite structure (TiO2(H)) as a negative electrode material for sodium-ion batteries are reported. TiO2(H) was obtained from K0.21TiO2 by an oxidation–ion extraction process. Na/TiO2(H) cells exhibit large first discharge capacity 280 mA h g−1 down to 0.2 V. After develop reversible charge–discharge 85 at C/8 rate in 2.5–0.2 V voltage range; this corresponds insertion 0.25 Na per formula unit. Chronoamperometry and potentiostatic...
A Li-rich layered oxide with the formula Li[Li0.2Mn0.61Ni0.18Mg0.01]O2 was successfully synthesised and characterised using several in situ characterisation techniques. The electronic state structural evolution of material upon cycling were investigated XRD, EXAFS XANES measurements. SQUID magnetic measurements showed that initial contains a certain amount Mn3+ low spin configuration (average Mn oxidation state: +3.75). In first part charge (up to 4.4 V vs. Li+/Li) corresponds fraction,...
Using an ultrahigh resolution (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mi mathvariant="normal">Δ</a:mi><a:mi>E</a:mi><a:mo>∼</a:mo><a:mn>0.1</a:mn><a:mspace width="0.16em"/><a:mi>eV</a:mi></a:mrow></a:math>) setup to measure electronic features in x-ray Thomson scattering (XRTS) experiments at the European XFEL Germany, we have studied collective plasmon excitation aluminium ambient conditions, which can very accurately even low momentum transfers. As a result,...
Controlling the formation and stoichiometric content of desired phases materials has become central interest for a variety fields. The possibility accessing metastable states by initiating reactions X-ray-triggered mechanisms over ultrashort time scales been enabled development X-ray free electron lasers (XFELs). Utilizing exceptionally high-brilliance pulses from EuXFEL, we report synthesis previously unobserved yttrium hydride under high pressure, along with nonstoichiometric changes in...
We present a detailed study of processes and interactions occurring during the Fe-catalyzed chemical vapor deposition carbon nanotubes on metallic Ta supports. In situ X-ray photoemission spectroscopy diffraction show that Fe catalyst increases reactivity toward oxidation carbide formation, whereas promotes reduction Fe. This causes an unusual temperature dependence nanotube growth, where at low temperatures (∼550 °C) vertically aligned forests with ohmic contacts grow readily Ta, high (>600...