ORCID Profile
0000-0002-1016-3802
Current Organisation
Kyushu University
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Publisher: Trans Tech Publications, Ltd.
Date: 04-2018
DOI: 10.4028/WWW.SCIENTIFIC.NET/SSP.273.95
Abstract: Cu 6 Sn 5 is an important intermetallic compound in soldering and electronic packaging. It is formed at the interface between molten solder and substrate during the soldering process, and the evolution of microstructure and properties also occurs in service. Previous studies revealed that Au and Ni are stabilization alloying elements for hexagonal η - Cu 6 Sn 5 intermetallic. For better understanding of stabilization mechanisms at atomic resolution level, in this work, we made an attempt atomic structure analysis on a stoichiometric (Cu, Au, Ni) 6 Sn 5 intermetallic prepared by direct alloying. High-angle annular dark-field (HAADF) imaging and atomic-resolution chemical mapping were taken by the aberration-corrected (Cs-corrected) scanning transmission electron microscopy (STEM). It is found that Au and Ni doped Cu 6 Sn 5 has hexagonal structure. The atom sites of Cu1 and Sn can be distinguished in atomic-resolution images after being observed from orientation [2110], which is also confirmed by atomic-resolution chemical mapping analysis. Importantly, atomic-resolution about distribution of alloying Au atom was directly observed, and Au atoms occupy the Cu1 sites in η - Cu 6 Sn 5 .
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 02-2017
Publisher: Springer Science and Business Media LLC
Date: 13-02-2015
DOI: 10.1038/SREP08450
Abstract: Hydrogen has the potential to power much of the modern world with only water as a by-product, but storing hydrogen safely and efficiently in solid form such as magnesium hydride remains a major obstacle. A significant challenge has been the difficulty of proving the hydriding/dehydriding mechanisms and, therefore, the mechanisms have long been the subject of debate. Here we use in situ ultra-high voltage transmission electron microscopy (TEM) to directly verify the mechanisms of the hydride decomposition of bulk MgH 2 in Mg-Ni alloys. We find that the hydrogen release mechanism from bulk (2 μm) MgH 2 particles is based on the growth of multiple pre-existing Mg crystallites within the MgH 2 matrix, present due to the difficulty of fully transforming all Mg during a hydrogenation cycle whereas, in thin s les analogous to nano-powders, dehydriding occurs by a ‘shrinking core’ mechanism.
Publisher: Wiley
Date: 13-03-2018
Abstract: For the first time, we synthesize solid‐solution alloy nanoparticles of Ir and Cu with a size of ca. 2 nm, despite Ir and Cu being immiscible in the bulk up to their melting over the whole composition range. We performed a systematic characterization on the nature of the Ir x Cu 1− x solid‐solution alloys using powder X‐ray diffraction, scanning transmission electron microscopy coupled with energy‐dispersive X‐ray spectroscopy and X‐ray photoelectron spectroscopy. The results showed that the Ir x Cu 1− x alloys had a face‐centered‐cubic structure charge transfer from Cu to Ir occurred in the alloy nanoparticles, as the core‐level Ir 4f peaks shifted to lower energy region with the increase in Cu content. Furthermore, we observed that the alloying of Ir with Cu enhanced both the electrocatalytic oxygen evolution and oxygen reduction reactions. The enhanced activities could be attributed to the electronic interaction between Ir and Cu arising from the alloying effect at atomic‐level.
Publisher: Elsevier BV
Date: 11-2012
Publisher: Wiley
Date: 10-03-2021
Publisher: American Chemical Society (ACS)
Date: 28-08-2020
Publisher: American Physical Society (APS)
Date: 17-06-2020
Publisher: Springer Science and Business Media LLC
Date: 07-04-2017
DOI: 10.1038/SREP43720
Abstract: In a comment on our Article “Evidence of the hydrogen release mechanism in bulk MgH 2 ”, Surrey et al . assert that the MgH 2 s le we studied was not MgH 2 at any time but rather MgO and that the transformation we observed was the formation of Kirkendall voids due to the outward diffusion of Mg. We address these issues in this reply.
No related grants have been discovered for Tomokazu Yamamoto.