ORCID Profile
0000-0003-3712-7307
Current Organisation
University of Tokyo
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Publisher: AIP Publishing
Date: 13-02-2012
DOI: 10.1063/1.3682310
Abstract: The atomic structure of a Σ3 [110]/(111) grain boundary in CeO2 was studied by scanning transmission electron microscopy, electron energy loss spectroscopy, and the first-principles calculations. It was revealed that this grain boundary does not promote the formation of oxygen vacancies and keeps oxygen stoichiometry, which is different from that of Σ5 CeO2 grain boundary studied previously [H. Hojo, T. Mizoguchi, H. Ohta, S. D. Findlay, N. Shibata, T. Yamamoto, and Y. Ikuhara, Nano Lett. 10, 4668 (2010)]. It was found that the difference in grain boundary oxygen stoichiometry is correlated with the grain boundary atomic structure.
Publisher: Elsevier BV
Date: 07-2011
DOI: 10.1016/J.ULTRAMIC.2011.02.009
Abstract: Motivated by the desire to minimize specimen damage in beam sensitive specimens, there has been a recent push toward using relatively low accelerating voltages (<100 kV) in scanning transmission electron microscopy. To complement experimental efforts on this front, this paper seeks to explore the variations with accelerating voltage of the imaging dynamics, both of the channelling of the fast electron and of the inelastic interactions. High-angle annular-dark field, electron energy loss spectroscopic imaging and annular bright field imaging are all considered.
Publisher: Author(s)
Date: 2016
DOI: 10.1063/1.4961356
Publisher: Wiley
Date: 23-02-2011
Publisher: Informa UK Limited
Date: 04-2013
Publisher: Oxford University Press (OUP)
Date: 08-2008
DOI: 10.1017/S1431927608084080
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008
Publisher: American Physical Society (APS)
Date: 03-04-2009
Publisher: American Chemical Society (ACS)
Date: 28-05-2013
DOI: 10.1021/NN400605Z
Abstract: Various dopants are added in commercially available optical glass fibers. The specific atomic species and charge state of lanthanide dopants are known to significantly influence the fiber's optical properties. For understanding the role of dopants on the optical properties, atomic-scale identification of the lanthanide dopants in the optical fiber is crucial. Aberration-corrected scanning transmission electron microscopy (STEM) is especially powerful for visualizing in idual atoms of heavy elements buried in a matrix composed of light elements. Here, we apply aberration-corrected high-angle annular dark field (HAADF)-STEM to directly visualize in idual erbium (Er) dopants buried in the optical glass fiber. Molecular dynamics and image simulations are used to interpret the experimental images and draw quantitative conclusions. The visibility of the buried Er atoms in the amorphous glass is strongly dependent on the defocus and specimen thickness, and only Er atoms in very thin regions can be reliably identified.
Publisher: Springer Science and Business Media LLC
Date: 21-06-2009
DOI: 10.1038/NMAT2486
Abstract: Determining the atomic structure of internal interfaces in materials and devices is critical to understanding their functional properties. Interfacial doping is one promising technique for controlling interfacial properties at the atomic scale, but it is still a major challenge to directly characterize in idual dopant atoms within buried crystalline interfaces. Here, we demonstrate atomic-scale plan-view observation of a buried crystalline interface (an yttrium-doped alumina high-angle grain boundary) using aberration-corrected Z-contrast scanning transmission electron microscopy. The focused electron beam transmitted through the off-axis crystals clearly highlights the in idual yttrium atoms located on the monoatomic layer interface plane. Not only is their unique two-dimensional ordered positioning directly revealed with atomic precision, but local disordering at the single-atom level, which has never been detected by the conventional approaches, is also uncovered. The ability to directly probe in idual atoms within buried interface structures adds new dimensions to the atomic-scale characterization of internal interfaces and other defect structures in many advanced materials and devices.
Publisher: American Physical Society (APS)
Date: 24-12-2008
Publisher: Informa UK Limited
Date: 08-2010
Publisher: American Association for the Advancement of Science (AAAS)
Date: 24-10-2008
Abstract: Determining the atomic structures of oxide surfaces is critical for understanding their physical and chemical properties but also challenging because the breaking of atomic bonds in the formation of the surface termination can involve complex reconstructions. We used advanced transmission electron microscopy to directly observe the atomic structure of reduced titania (TiO 2 ) (110) surfaces from directions parallel to the surface. In our direct atomic-resolution images, reconstructed titanium atoms at the top surface layer are clearly imaged and are found to occupy the interstitial sites of the TiO 2 structure. Combining observations from two orthogonal directions, the three-dimensional positioning of the Ti interstitials is identified at atomic dimensions and allows a resolution of two previous models that differ in their oxygen stoichiometries.
Publisher: Oxford University Press (OUP)
Date: 08-2008
DOI: 10.1017/S1431927608086376
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008
Publisher: American Chemical Society (ACS)
Date: 26-10-2010
DOI: 10.1021/NL1029336
Abstract: Determining both cation and oxygen sublattices of grain boundaries is essential to understand the properties of oxides. Here, with scanning transmission electron microscopy, electron energy-loss spectroscopy, and first-principles calculations, both the Ce and oxygen sublattices of a (210)Σ5 CeO(2) grain boundary were determined. Oxygen vacancies are shown to play a crucial role in the stable grain boundary structure. This finding paves the way for a comprehensive understanding of grain boundaries through the atomic scale determination of atom and defect locations.
Publisher: Oxford University Press (OUP)
Date: 07-2009
DOI: 10.1017/S1431927609093775
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009
Publisher: AIP Publishing
Date: 07-05-2012
DOI: 10.1063/1.4714920
Abstract: The defect structures around oxygen vacancies in perovskite-type oxides play very important roles in determining material properties through the change of the electronic state. Therefore, from the viewpoint of developing condensed matter physics and technological applications, it is crucial to obtain direct images of these structures. We report the simultaneous visualization of oxygen vacancies and the cation shifts around them in perovskite-type manganite by scanning transmission electron microscopy. The defective structure of the material makes it amenable to using Fourier analysis to obtain important structural information like the oxygen vacancy locations and the shift of nearby cation columns.
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.ULTRAMIC.2011.08.013
Abstract: The analysis of grain boundary structure in high resolution electron microscopy is often hindered by contrast variation within the grain boundary region which is not explained by simple models of the grain boundary structure. Recent work suggests that structural disorder along the beam direction and the presence of vacancies contribute significantly to this effect. One might expect a significant reduction in contrast in a Z-contrast image of a grain boundary would imply that vacancies present must result from the absence of heavier elements. Using a [001](210) Σ5 grain boundary in SrTiO(3) as a test case and first principles structure relaxation to calculate stable defect structures, we show that the reduction in the intensity from fully occupied Sr columns due to the structural distortion resulting from a nearby O vacancy can be as great as that due to introducing a Sr vacancy in the column itself. The effect on energy dispersive X-ray spectroscopy signals is also considered, but found to be smaller than that on Z-contrast images.
No related grants have been discovered for Teruyasu Mizoguchi.