A5033023422- Electron and X-Ray Spectroscopy Techniques
- Semiconductor materials and devices
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced X-ray Imaging Techniques
- Surface and Thin Film Phenomena
- Photocathodes and Microchannel Plates
- Advanced Electron Microscopy Techniques and Applications
- Electronic and Structural Properties of Oxides
- Semiconductor materials and interfaces
- Advancements in Battery Materials
- Advanced Chemical Physics Studies
- Advancements in Photolithography Techniques
- Advanced Battery Technologies Research
- Integrated Circuits and Semiconductor Failure Analysis
- Diamond and Carbon-based Materials Research
- Silicon and Solar Cell Technologies
- Nuclear Physics and Applications
- Semiconductor Quantum Structures and Devices
- Silicon Nanostructures and Photoluminescence
- Advancements in Semiconductor Devices and Circuit Design
- Particle Accelerators and Free-Electron Lasers
- Advanced Battery Materials and Technologies
- Advanced X-ray and CT Imaging
- Ion-surface interactions and analysis
- Ga2O3 and related materials
SLAC National Accelerator Laboratory
2016-2025
Stanford Synchrotron Radiation Lightsource
2016-2025
Stanford University
2010-2023
Argonne National Laboratory
1993-2023
Central South University
2023
The University of Texas at Austin
2023
Center for Research and Advanced Studies of the National Polytechnic Institute
1999-2023
Virginia Tech
2023
Purdue University West Lafayette
2023
Walker (United States)
2023
Abstract Nickel‐rich layered materials LiNi 1‐x‐y Mn x Co y O 2 are promising candidates for high‐energy‐density lithium‐ion battery cathodes. Unfortunately, they suffer from capacity fading upon cycling, especially with high‐voltage charging. It is critical to have a mechanistic understanding of such fade. Herein, synchrotron‐based techniques (including scattering, spectroscopy, and microcopy) finite element analysis utilized understand the 0.6 0.2 material structural, chemical,...
The ability to probe morphology and phase distribution in complex systems at multiple length scales unravels the interplay of nano- micrometer-scale factors origin macroscopic behavior. While different electron- X-ray-based imaging techniques can be combined with spectroscopy high resolutions, owing experimental time limitations resulting fields view are too small representative a composite sample. Here new X-ray set-up is proposed, combining full-field transmission microscopy (TXM)...
Transmission X-ray microscopy (TXM) has been well recognized as a powerful tool for non-destructive investigation of the three-dimensional inner structure sample with spatial resolution down to few tens nanometers, especially when combined synchrotron radiation sources. Recent developments this technique have presented need new tools both system control and data analysis. Here software package developed in MATLAB script command generation analysis TXM is presented. The first toolkit,...
Abstract The multiscale chemomechanical interplay in lithium‐ion batteries builds up mechanical stress, provokes morphological breakdown, and leads to state of charge heterogeneity. Quantifying the complex composite electrodes with resolution constitutes a frontier challenge precisely diagnosing fading mechanism batteries. In this study, hard X‐ray phase contrast tomography, capable nanoprobing thousands active particles at once, enables an unprecedented statistical analysis transformation...
Abstract The microstructure of a composite electrode determines how individual battery particles are charged and discharged in lithium-ion battery. It is frontier challenge to experimentally visualize and, subsequently, understand the electrochemical consequences particles’ evolving (de)attachment with conductive matrix. Herein, we tackle this issue unique combination multiscale experimental approaches, machine-learning-assisted statistical analysis, experiment-informed mathematical...
For designing new battery systems with higher energy density and longer cycle life, it is important to understand the degradation mechanism of electrode material, especially at individual particle level. Using in situ transmission X-ray microscopy (TXM) coupled a pouch cell setup, inhomogeneous Li distribution as well formation, population, evolution inactive domains single LiCoO2 were visualized was cycled for many times. It found that percentage fully recovered pristine state strongly...
Improving composite battery electrodes requires a delicate control of active materials and electrode formulation. The electrochemically particles fulfill their role as energy exchange reservoirs through interacting with the surrounding conductive network. We formulate network evolution model to interpret regulation equilibration between electrochemical activity mechanical damage these particles. Through statistical analysis thousands using x-ray phase contrast holotomography in...
The bonding of alkyl monolayers to Si(111) surfaces has been studied by conventional x-ray photoelectron spectroscopy (XPS) and chemical-shift, scanned-energy diffraction (PED) using synchrotron radiation. Two very different wet-chemical methods have used prepare the monolayers: (i) olefin insertion into H–Si bond on H–Si(111) surface, (ii) replacement Cl Cl–Si(111) surface an group from alkyllithium reagent. In both cases, XPS revealed a C 1s signal chemically shifted lower binding energy,...
We measured the elemental compositions of material from 23 particles in aerogel and residue seven craters aluminum foil that was collected during passage Stardust spacecraft through coma comet 81P/Wild 2. These are chemically heterogeneous at largest size scale analyzed (â¼180 ng). The mean composition this Wild 2 is consistent with CI meteorite composition, which thought to represent bulk solar system, for elements Mg, Si, Mn, Fe, Ni 35%, Ca Ti 60%. Cu, Zn, Ga appear enriched material,...
The surface chemistry of cleaved GaAs(110) (and, to a lesser extent, InP and GaSb) is studied as function oxygen exposure (both unexcited excited) with soft-x-ray photoemission spectroscopy. When the GaAs (110) exposed molecular in ground state, chemisorption only arsenics takes place. No back bonds are broken even for large exposures. Room-temperature oxidation can be induced by exciting oxygen, e.g., an ionization gauge. adsorption excited initially same unexcited, except 500 times faster....
Passivation of Ge has been a critical issue for MOS applications in future technology nodes. In this letter, we introduce ozone oxidation to engineer Ge/insulator interface. Density interface states (D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">it</sub> ) across the bandgap and close conduction band edge was extracted using conductance technique at low temperatures. D dependence on growth conditions studied. Minimum 3 times 10 <sup...
Understanding the evolution of chemical composition and morphology battery materials during electrochemical cycling is fundamental to extending cycle life ensuring safety. This particularly true for much debated high energy density (high voltage) lithium-manganese rich cathode material Li(1 + x)M(1 - x)O2 (M = Mn, Co, Ni). In this study we combine full-field transmission X-ray microscopy (TXM) with absorption near edge structure (XANES) spatially resolve changes in phase, oxidation state,...
Bone is a dynamically remodeled tissue that requires gravity-mediated mechanical stimulation for maintenance of mineral content and structure. Homeostasis in bone occurs through balance the activities signaling osteoclasts, osteoblasts, osteocytes, as well proliferation differentiation their stem cell progenitors. Microgravity unloading are known to cause osteoclast-mediated resorption; however, we hypothesize osteocytic osteolysis, cycle arrest during osteogenesis may also contribute loss...
Photoemission spectroscopy, constant-final-state and ion-depth profiling techniques were applied to the study of formation Au Schottky barrier on cleaved GaSb, GaAs, InP. It is found that deposited interacts strongly with semiconductors, causing decomposition their surfaces. Further, Fermi-level pinning nearly complete at 0.2-monolayer coverage, when still "atomiclike." suggested defect states interface are responsible for Schottky-barrier pinning, a mechanism creation proposed. appears many...
Photoelectron spectroscopy (PES) and Auger electron have been used to study the early stages of oxidation cleaved silicon (111) surface. The Si-$2p$ core level as well valence emission were studied with PES, using monochromatized synchrotron radiation at a photon energy which allows maximum surface sensitivity. In initial adsorption stage (i.e., when states are removed from band gap), oxygen can be adsorbed either molecularly or atomically. chemisorbed was characterized by zero shift level,...
The oxidation properties of GaAs(110), GaSb(110), and InP(110) have been studied with the photoemission technique using synchrotron radiation. One part work consisted an investigation chemical shifts in core levels upon adsorption oxygen submonolayer quantities. For GaAs InP, removed electrons preferentially from surface column V elements (As P), leaving III (Ga In) unaffected; whereas, for GaSb, both constitutents were involved suggesting a breaking bonds between atoms rest crystal. second...
Abstract Surface lattice reconstruction is commonly observed in nickel-rich layered oxide battery cathode materials, causing unsatisfactory high-voltage cycling performance. However, the interplay of surface chemistry and bulk microstructure remains largely unexplored due to intrinsic structural complexity lack integrated diagnostic tools for a thorough investigation at complementary length scales. Herein, by combining nano-resolution X-ray probes both soft hard regimes, we demonstrate...
Low work function materials are critical for energy conversion and electron emission applications. Here, we demonstrate the first time that an ultralow graphene is achieved by combining electrostatic gating with a Cs/O surface coating. A simple device built from large-area monolayer grown chemical vapor deposition, transferred onto 20 nm HfO2 on Si, enabling high electric fields capacitive charge accumulation in graphene. We observed over 0.7 eV change due to as measured scanning Kelvin...