A5016118802- Solid-state spectroscopy and crystallography
- Advanced Battery Materials and Technologies
- Fuel Cells and Related Materials
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Advancements in Solid Oxide Fuel Cells
- Material Dynamics and Properties
- Advancements in Battery Materials
- Perovskite Materials and Applications
- Advanced NMR Techniques and Applications
- Membrane-based Ion Separation Techniques
- High-pressure geophysics and materials
- Crystallization and Solubility Studies
- Glass properties and applications
- Thermal Expansion and Ionic Conductivity
- Ferroelectric and Piezoelectric Materials
- Protein Structure and Dynamics
- Hydrogen Storage and Materials
- Ionic liquids properties and applications
- X-ray Diffraction in Crystallography
- Crystal Structures and Properties
- Nuclear Materials and Properties
- Spectroscopy and Quantum Chemical Studies
- Nuclear Physics and Applications
- Phase Equilibria and Thermodynamics
Oak Ridge National Laboratory
2016-2025
Forschungszentrum Jülich
2013-2022
Oak Ridge Associated Universities
2017-2021
Louisiana State University
2018
Alfred University
2018
City University of Hong Kong
2018
Stadtwerke Jülich (Germany)
2015
University of Oslo
2009-2013
Spallation Neutron Source
2013
Universidad de Oviedo
2011
The relaxational dynamics in glass-forming glycerol and mixed with LiCl is in-vestigated using different neutron scattering techniques. performed spin-echo experiments, which extend up to relatively long relaxation-time scales of the order 10 ns, should allow for detection contributions from so-called excess wing. This phenomenon, whose microscopic origin controversially discussed, arises a variety glass formers and, until now, was almost exclusively investigated by dielectric spectros-copy...
The emission of white light from a single material is atypical and interest for solid-state lighting applications. Broadband has been observed in some layered perovskite derivatives, A2PbBr4 (A = R-NH3+), correlates with static structural distortions corresponding to out-of-plane tilting the lead bromide octahedra. While materials different organic cations can yield distinct tilts, underlying origin octahedral remains poorly understood. Using high energy resolution (e.g., quasi-elastic)...
Neutron and electron spectroscopy reveal diffusion behavior of individual ions in lithium garnets, paving the way towards high-performance aqueous batteries.
Inorganic Na-ion superionic conductors play a vital role in all-solid-state Na batteries that operate at room temperature. Sodium thioantimonate (Na3SbS4), popular sulfide-based solid electrolyte, has attracted serious attention due to its advantages of high ionic conductivity temperature and impressive chemical stability under ambient conditions. Much research detailing Na3SbS4 focused on synthetic approaches interfacial against metal, yet, there is limited information elucidating...
Aliovalent substitution is a common strategy to improve the ionic conductivity of solid electrolytes for solid-state batteries. The SbS43- by WS42- in Na2.9Sb0.9W0.1S4 leads very high 41 mS cm-1 at room temperature. While pristine Na3SbS4 crystallizes tetragonal structure, substituted cubic phase temperature based on its X-ray diffractogram. Here, we show performing pair distribution function analyses and static single-pulse 121Sb NMR experiments that short-range order remains despite change...
The dynamics of proteins in solution is a complex and hierarchical process, affected by the aqueous environment as well temperature. We present comprehensive study on nanosecond time nanometer length scales below, at, above denaturation temperature Td. Our experimental data evidence dynamical processes protein solutions three distinct scales. suggest consistent physical picture dynamics: (i) self-diffusion entire molecule confirmed to agree with colloid theory for all temperatures where its...
Hybrid organic–inorganic perovskites have gained notoriety in the photovoltaic community for their composition-tunable band gaps and long-lived electronic excited states, which are known to be related crystalline phase. While it is that inorganic organic components coupled through structural phase transitions, remains unclear as what role each plays directing structure of hybrid such methylammonium lead halides (CH3NH3PbX3). Here, we present crystallographic spectroscopic data series...
Polyoligosilsesquioxanes (POSS) are a large family of Si–O cage molecules that have diameters 1–2 nm and can be viewed as perfectly monodisperse silica nanoparticles. POSS synthesized with wide variety functional ligands attached to their surfaces. Here we report the results comprehensive study crystal structure ligand dynamics one simplest nanoparticles, octamethyl-POSS or Si8O12(CH3)8, where central Si8O12 is surrounded by eight methyl ligands. Neutron powder diffraction data highlight...
Molecular motion of hydrocarbons under confinement exhibits several peculiarities and has important implications in industries like gas recovery. A quasielastic neutron scattering (QENS) study the dynamics propane nanoporous silica aerogel was carried out to quantify its molecular mobility. The dynamical properties were studied as a function temperature, pressure presence CO2. effects pressure, i.e., fluid density composition, are found be more pronounced than temperature. At low pressures...
Engineering the composition of perovskite active layers has been critical in increasing efficiency solar cells (PSCs) to more than 25% latest reports. Partial substitutions monovalent cation and halogen have adopted highest-performing devices, but precise role bromine incorporation remains incompletely explained. Here we use quasi-elastic neutron scattering (QENS) study, as a function degree incorporation, dynamics organic cations triple-cation lead mixed-halide perovskites. We find that...
The temperature-dependent diffusivity D(T) of hydrogen solute atoms trapped at dislocations-dislocation pipe diffusion hydrogen-in deformed polycrystalline PdH(x) (x∼10(-3) [H]/[Pd]) has been quantified with quasielastic neutron scattering between 150 and 400 K. We observe coefficients for elevated by one to two orders magnitude above bulk diffusion. Arrhenius behavior observed dislocation regular diffusion, the latter in well-annealed Pd. For Pd we find D(T)=D(0)exp(-E(a)/kT)=0.005exp(-0.23...
We report a comprehensive specific heat and inelastic neutron scattering study to explore the possible origin of multiferroicity in HoCrO3. have performed measurements temperature range 100 mK–290 K were 1.5–200 K. From data we determined hyperfine splitting at 22.5(2) μeV crystal field transitions 1.379(5) meV, 10.37(4) 15.49(9) meV 23.44(9) indicating existence strong interactions Further, an effective is be 600(3) T. The quasielastic observed large linear term mJ mol−1 K−2 attributed...
We report a neutron-scattering investigation on the structure and dynamics of single-component nanocomposite based SiO_{2} particles that were grafted with polyisoprene chains at entanglement limit. By skillful labeling, we access both monomer density in corona as well conformation chains. While profile follows r^{-1} power law, chain is identical to reference melt, implying high mutual penetration coronas from different particles. The brush crowding leads topological confinement dynamics:...
Molecular dynamics plays an important role for the biological function of proteins. For protein ligand interactions, changes conformational entropy and hydration layer are relevant binding process. Quasielastic neutron scattering (QENS) was used to investigate differences in ligand-bound ligand-free streptavidin. Protein were probed both on fast picosecond time scale using time-of-flight spectroscopy slower nanosecond high-resolution backscattering spectroscopy. We found internal equilibrium...
Translation and rotation are the two most fundamental forms of diffusion, yet their coupling mechanism is not clear, especially under confinement. Here, we provided evidence between translation using a substituted benzene molecule as an example. A counterintuitive behavior was observed where movement smaller with asymmetric shape unexpectedly slower than larger one symmetric in confined channels zeolite. We showed that this diffusion caused by presence specific selective interaction guest...
NASICON (sodium superionic conductor) based ceramics are one of the most promising classes solid-state electrolytes for all-solid-state batteries. However, mechanism sodium ion diffusion is not understood in...
Proteins in solution move subject to a complex superposition of global translational and rotational diffusion as well internal relaxations covering wide range time scales. With the advent new high-flux neutron spectrometers combination with enhanced analysis frameworks it has become possible separate these different contributions. We discuss approaches by presenting example spectra fits from data recorded on backscattering IN16, IN16B, BASIS same protein sample. illustrate separation...
Relaxor ferroelectrics exhibit frequency-dispersion of their dielectric permittivity peak as a function temperature, the origin which has been widely debated. Microscopic understanding such behavior for polymeric presented new challenges since unlike traditional ceramic ferroelectrics, relaxation in polymers is consequence short-range molecular dynamics that are difficult to measure directly. Here, through careful analysis atomic-level H-atom determined by Quasi-elastic Neutron Scattering...
The bulk conductivity of polycrystalline 1 mol-% Fe-doped rutile TiO2 has been measured as a function pH2O and temperature under oxidizing reducing conditions. From the pH2O-dependency conductivity, it is concluded that protons are significant positive defects and, furthermore, mixed p-type electronic protonic, n-type conduction dominate conditions, respectively. H2O/D2O isotope exchange confirmed charge carriers wet conditions below approximately 600 °C. Thermodynamic parameters for...