A5025115942- Electron and X-Ray Spectroscopy Techniques
- Advanced Electron Microscopy Techniques and Applications
- Electronic and Structural Properties of Oxides
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Advanced Fiber Optic Sensors
- Advancements in Battery Materials
- Photonic and Optical Devices
- Advanced Battery Materials and Technologies
- Integrated Circuits and Semiconductor Failure Analysis
- Advanced Materials Characterization Techniques
- Advanced X-ray Imaging Techniques
- Ferroelectric and Piezoelectric Materials
- Semiconductor materials and devices
- Magnetic and transport properties of perovskites and related materials
- Advanced ceramic materials synthesis
- Catalytic Processes in Materials Science
- Inorganic Fluorides and Related Compounds
- Advanced Fiber Laser Technologies
- Semiconductor Lasers and Optical Devices
- Multiferroics and related materials
- Advanced Battery Technologies Research
- Surface and Thin Film Phenomena
- Force Microscopy Techniques and Applications
- Microstructure and mechanical properties
The University of Tokyo
2015-2024
Saitama University
2015-2024
Bunkyo University
2024
Institute of Engineering
2016-2024
Nagoya University
2023
University of Tokyo Hospital
2023
Japan Science and Technology Agency
2019-2022
Tokyo Institute of Technology
2008-2019
Yamaguchi University
2013-2015
Oak Ridge National Laboratory
2013-2014
About phase: The coexistence of rhombohedral LiTMO2 (TM=Ni, Co, or Mn) and monoclinic Li2MnO3-like structures inside Li1.2Mn0.567Ni0.166Co0.067O2 is revealed directly at atomic resolution. hetero-interface along the [001]rh/[103]mon zone axis direction demonstrated, indicating two-phase nature these lithium-rich cathode materials (green Li, blue Mn, red O, cyan TM).
Li-ion-conducting solid electrolytes are the potential solution to severe safety issues that occur with conventional batteries based on solvent-based electrolytes. The ionic conductivity of is in general too low, however, due a high grain-boundary (GB) resistance. A thorough understanding transport mechanism at GBs these materials critical for revolutionary development next-generation Li batteries. Herein we present first atomic-scale study reveal origin large GB resistance;...
Abstract Owing to their remarkable properties, gold nanoparticles are applied in diverse fields, including catalysis, electronics, energy conversion and sensors. However, for catalytic applications of colloidal nanoparticles, the trade-off between reactivity stability is a significant concern. Here we report universal approach preparing stable reactive small (~3 nm) by using multi-dentate polyoxometalates as protecting agents non-polar solvents. These exhibit exceptional even under...
Abstract In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both positive atomic nuclei and surrounding negative within crystalline materials probed atomic-resolution differential phase contrast STEM. Here we demonstrate real-space imaging (projected) distribution inside Au atoms, sub-Å spatial...
Although the size effect in ferroelectric thin films has been known for long time, underlying mechanism is not yet fully understood and whether or there a critical thickness below which ferroelectricity vanishes still under debate. Here, we directly measure thickness-dependent polarization ultrathin PbZr0.2Ti0.8O3 via quantitative annular bright field imaging. We find that significantly suppressed <10-unit cells thick (∼4 nm). However, approximately never vanishes. The residual ∼16 μCcm-2...
LaTiO2N is an oxynitride photocatalyst that has ability to generate H2 and O2 from water under irradiation of light with wavelengths up 600 nm. However, necessitates sacrificial reagents capture either photoexcited electrons or holes efficiently be active in the photocatalytic reactions because a considerable number defects cause trapping recombination carriers. Therefore, identifying defect structures important. In this study, using atomic-resolution scanning transmission electron...
Noble metal nanoparticles (e.g., gold and platinum) supported on TiO2 surfaces are utilized in many technological applications such as heterogeneous catalysts. To fully understand their enhanced catalytic activity, it is essential to unravel the interfacial interaction between atoms at level of atomic dimensions. However, has been extremely difficult directly characterize atomic-scale structures that result when individual adsorbed surfaces. Here, we show direct atomic-resolution images Pt...
Owing to the broken translational symmetry at dislocations, a strain gradient naturally exists around dislocation cores and can significantly influence electrical mechanical properties. We use aberration corrected scanning transmission electron microscopy directly measure flexoelectric polarization (∼28 μC cm^{-2}) in SrTiO_{3}. The charges interact with nonstoichiometric thus impact activities. Our findings help us understand properties of dislocations perovskite, providing new insights...
We study the second-order Raman process of mono- and few-layer MoTe$_2$, by combining {\em ab initio} density functional perturbation calculations with experimental spectroscopy using 532, 633 785 nm excitation lasers. The calculated electronic band structure states show that electron-photon resonance occurs at high-symmetry M point in Brillouin zone, where a strong optical absorption logarithmic Van-Hove singularity. Double scattering inter-valley electron-phonon coupling connects two three...
Diffusion is one of the fundamental processes that govern structure, processing, and properties materials it plays a crucial role in determining device lifetimes. However, direct observations diffusion have been elusive limited only to surfaces materials. Here we use an aberration-corrected electron microscope locally excite directly image single Ce Mn dopants inside bulk wurtzite-type AlN crystals, identifying correlated vacancy-dopant interstitial-dopant kick-out mechanisms. Using 200 kV...
Materials properties, such as optical and electronic response, can be greatly enhanced by isolated single dopants. Determining the full three-dimensional single-dopant defect structure spatial distribution is therefore critical to understanding adequately tuning functional properties. Combining quantitative Z-contrast scanning transmission electron microscopy images with image simulations, we show direct determination of atomic-scale depth location an optically active, atom Ce dopant...
Encapsulating metal nanoclusters into zeolites combines the superior catalytic activity of with high stability and unique shape selectivity crystalline microporous materials. The preparation such bifunctional catalysts, however, is often restricted by mismatching in time scale between fast formation slow crystallization zeolites. We herein demonstrate a novel strategy to overcome issue, which expedited so as synchronize it rapid nanoclusters. concept was demonstrated confining Pt Sn ZSM-5...
Abstract Material properties are sensitive to atomistic structure defects such as vacancies or impurities, and it is therefore important determine not only the local atomic configuration but also their chemical bonding state. Annular dark-field scanning transmission electron microscopy (STEM) combined with energy-loss spectroscopy has been utilized investigate electronic structures of down level single atoms. However, still challenging two-dimensionally map states, because fine-structure...
The rich functionalities in the ABO3 perovskite oxides originate, at least part, from ability of corner-connected BO6 octahedral network to host a large variety cations through distortions and rotations. Characterizing these rotations, which have significant impact on both fundamental aspects materials behavior possible applications, remains major challenge heterointerfaces. In this work, we developed unique method investigate rotation patterns complex with unit cell resolution...
Abstract One of the difficulties in analyzing atomic resolution electron microscope images is that sample thickness usually unknown or has to be fitted from parameters are not precisely known. An accurate measure thickness, ideally on a column-by-column basis, parameter free, and with single atom accuracy, would great value for many applications, such as matching simulations. Here we propose quantification method annular dark field scanning transmission microscopy by using intensity level...
Abstract At the ferroelectric surface, broken translational symmetry induced bound charge should significantly alter local atomic configurations. Experimentally revealing structure of however, is very challenging due to strong spatial variety between nano-sized domains, and interactions polarization other structural parameters. Here, we study surface structures Pb(Zr 0.2 Ti 0.8 )O 3 thin film by using annular bright-field imaging. We find that six layers with suppressed a charged 180° domain...
Studies on dislocations in prototypic binary and ternary oxides (here TiO2 SrTiO3) using modern TEM scanning probe microscopy (SPM) techniques, combined with classical etch pits methods, are reviewed. Our review focuses the important role of insulator-to-metal transition for redox processes, which can be preferentially induced along chemical electrical gradients. It is surprising that, independently growth density surface layers both prototypical high (109/cm2 epipolished surfaces up to...
Abstract Glasses and single crystals have traditionally been used as optical windows. Recently, there has a high demand for harder tougher windows that are able to endure severe conditions. Transparent polycrystalline ceramics can fulfill this because of their superior mechanical properties. It is known with spinel structure in compositions MgAl 2 O 4 aluminum oxynitride (γ-AlON) show transparency. Here we report the synthesis hardest transparent ceramic, i.e. cubic silicon nitride (c-Si 3 N...
We investigate the hydrostatic pressure dependence of Bragg wavelength a fiber grating (FBG) inscribed in perfluorinated graded-index (PFGI-) polymer optical (POF) at 1550 nm. At 0.5 MPa, increased with time and became almost constant ~150 min later. Such long probably originates from unique structure PFGI-POF, which has thick overcladding around its core cladding. The pressure-dependence coefficient without considering was estimated to be 1.3 nm/MPa; this is over five times values other...
Abstract Lithium-excess layered cathode materials such as Li 2 MnO 3 have attracted much attention owing to their high energy densities. It has been proposed that oxygen-release and cation-mixing might be induced by delithiation. However, it is still unclear how the delithiated-region grows. Here, using atomic-resolution scanning transmission electron microscopy combined with energy-loss spectroscopy, we directly observe atomic structures at interface between pristine delithiated regions in...
Single and multi-atoms supported on oxide substrates ultimately increase the efficiency of noble metal atom use, moreover, catalytic activity selectivity are also improved substantially. However, single unstable under conditions, these atoms spontaneously aggregate grow into nanoparticles. Catalytic performance is strongly related to local atomic configurations, hence, it essential determine three-dimensional (3D) structures substrate their structural dynamics. Here, we show real-time...