Updated on 2024/12/27

Information

 

写真a

 
SAITO HIKARU
 
Organization
Institute for Materials Chemistry and Engineering Department of Integrated Materials Associate Professor
Interdisciplinary Graduate School of Engineering Sciences Department of Interdisciplinary Engineering Sciences(Concurrent)
Title
Associate Professor
Contact information
メールアドレス
Tel
0925837621
Homepage

Degree

  • PhD (Science)

Research History

  • 2014.04 - 2015.03 東京工業大学量子ナノエレクロニクス研究センター・研究員

Research Interests・Research Keywords

  • Research theme:Rapid electron tomography assisted by machine learning

    Keyword:electron tomography, machine learning

    Research period: 2020.7

  • Research theme:3D observation of ferromagnetic material by magnetic-field-free STEM

    Keyword:Tomography, Lorentz-STEM, Iron and steel, magnetic material

    Research period: 2015.10

  • Research theme:Interactions between metals and oxides characterized by electron energy-loss spectroscopy

    Keyword:catalysis, perovskite, EELS, electron microscopy

    Research period: 2015.4

  • Research theme:Plasmonic crystals characterized by scanning transmission electron microscopy-cathodoluminescence

    Keyword:surface plasmon polariton, topological edge mode, valleytronics, plasmonic crystal, waveguide, luminescence enhancement, electron microscopy

    Research period: 2014.4

  • Research theme:Optical property of nanostructural material characterized by angle-resolved electron energy-loss spectroscopy

    Keyword:EELS, electron microscopy, photonics, plasmonics

    Research period: 2011.4

Awards

  • 日本顕微鏡学会奨励賞

    2022.5   日本顕微鏡学会   電子線顕微分光によるプラズモニクス材料の研究

  • 日本物理学会若手奨励賞

    2021.3   日本物理学会   電子線分光によるプラズモニック結晶の研究

  • 日本顕微鏡学会論文賞

    2017.6   日本顕微鏡学会  

  • 風戸研究奨励賞

    2015.2   風戸研究奨励会  

Papers

  • Diffusion-Dominated Luminescence Dynamics of CsPbBr3 Studied Using Cathodoluminescence and Microphotoluminescence Spectroscopy Reviewed International journal

    Sho Nekita, Sotatsu Yanagimoto, Takumi Sannomiya, Keiichirou Akiba, Masato Takiguchi, Hisashi Sumikura, Itsuki Takagi, Kazutaka G Nakamura, SenPo Yip, You Meng, Johnny C Ho, Tetsuya Okuyama, Mitsuhiro Murayama, Hikaru Saito

    Nano Letters   24 ( 13 )   3971 - 3977   2024.3

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    Language:English   Publishing type:Research paper (scientific journal)  

  • Five-second STEM dislocation tomography for 300 nm thick specimen assisted by deep-learning-based noise filtering Reviewed International journal

    Yifang Zhao, Suguru Koike, Rikuto Nakama, Shiro Ihara, Masatoshi Mitsuhara, Mitsuhiro Murayama, Satoshi Hata, Hikaru Saito

    Scientific reports   11 ( 1 )   1 - 12   2021.10

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    Language:English   Publishing type:Research paper (scientific journal)  

    Other Link: https://www.nature.com/articles/s41598-021-99914-5

  • Valley-polarized plasmonic edge mode visualized in the near-infrared spectral range Reviewed International journal

    Hikaru Saito, Daichi Yoshimoto, Yuto Moritake, Taeko Matsukata, Naoki Yamamoto, Takumi Sannomiya

    Nano Letters   21 ( 15 )   6556 - 6562   2021.7

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    Language:English   Publishing type:Research paper (scientific journal)  

    Other Link: https://pubs.acs.org/doi/full/10.1021/acs.nanolett.1c01841

  • Emergence of point defect states in a plasmonic crystal Reviewed

    Physical Review B   100 ( 24 )   2019.12

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1103/PhysRevB.100.245402

  • Hybridization of Gap Modes and Lattice Modes in a Plasmonic Resonator Array with a Metal-Insulator-Metal Structure Reviewed

    Hikaru Saito, Daichi Yoshimoto, Hugo Lourenco-Martins, Naoki Yamamoto, Takumi Sannomiya

    ACS Photonics   2019.1

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acsphotonics.9b00977

  • Characterization of Nonradiative Bloch Modes in a Plasmonic Triangular Lattice by Electron Energy-Loss Spectroscopy Reviewed

    Daichi Yoshimoto, Hikaru Saito, Satoshi Hata, Yoshifumi Fujiyoshi, Hiroki Kurata

    ACS Photonics   5 ( 11 )   4476 - 4483   2018.11

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acsphotonics.8b00936

  • Three-dimensional visualization of dislocations in a ferromagnetic material by magnetic-field-free electron tomography Reviewed

    Kana L. Hasezaki, Hikaru Saito, Takumi Sannomiya, Hiroya Miyazaki, Takashi Gondo, Shinsuke Miyazaki, Satoshi Hata

    Ultramicroscopy   182   249 - 257   2017.11

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.ultramic.2017.07.016

  • Waveguide Bandgap in Crystalline Bandgap Slows Down Surface Plasmon Polariton Reviewed

    Hikaru Saito, Naoki Yamamoto, Takumi Sannomiya

    ACS Photonics   4 ( 6 )   1361 - 1370   2017.6

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acsphotonics.6b00943

  • Confinement of Surface Plasmon Polaritons by Heterostructures of Plasmonic Crystals Reviewed

    Hikaru Saito, Shohei Mizuma, Naoki Yamamoto

    Nano Letters   15 ( 10 )   6789 - 6793   2015.10

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acs.nanolett.5b02623

  • Control of Light Emission by a Plasmonic Crystal Cavity Reviewed

    Hikaru Saito, Naoki Yamamoto

    Nano Letters   15 ( 9 )   5764 - 5769   2015.9

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acs.nanolett.5b01719

  • Size dependence of bandgaps in a two-dimensional plasmonic crystal with a hexagonal lattice Reviewed

    Hikaru Saito, Naoki Yamamoto

    Optics Express   23 ( 3 )   2524 - 2540   2015.2

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1364/OE.23.002524

  • Dispersion relations for coupled surface plasmon-polariton modes excited in multilayer structures Reviewed

    Hikaru Saito, Kyoko Namura, Motofumi Suzuki, Hiroki Kurata

    Microscopy   63 ( 1 )   85 - 93   2014.1

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1093/jmicro/dft047

  • Optical guided modes coupled with Čerenkov radiation excited in Si slab using angular-resolved electron energy-loss spectrum Reviewed

    113 ( 11 )   2013.3

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    Language:English   Publishing type:Research paper (scientific journal)  

    Retardation effects in the valence electron energy-loss spectrum (EELS) of a Si slab are analyzed by angular-resolved EELS. The dispersion curves of the valence spectra excited in a slab are directly observed from a specimen area with several different thicknesses and are interpreted by performing a calculation of the dispersion relation using Krögers formula. The dispersion curves observed below about 3 eV are attributed to guided modes coupled with Čerenkov radiation (ČR). The coupling between guided modes and ČR is found to be dependent on the sample thickness (t). For the sample with t > 150 nm, the intensity of the guided modes increased linearly with thickness, revealing the coupling with ČR. For t 150 nm, however, the intensity of the guided modes rapidly decreased due to a diminished coupling with ČR, resulting from the thickness-dependent dispersion curves of the guided modes.

    DOI: 10.1063/1.4796140

  • Molecular-Templated ALD on Mixed SAM to Achieve Unimolecular Dispersion and In-Process Fluorescent Monitoring of Template Molecules

    Ono, T; Hosomi, T; Saito, H; Masai, H; Ikeuchi, M; Liu, JY; Tanaka, W; Takahashi, T; Kanai, M; Terao, J; Yanagida, T

    ADVANCED MATERIALS TECHNOLOGIES   2024.12   ISSN:2365-709X

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    Publisher:Advanced Materials Technologies  

    Atomic layer deposition (ALD) in the presence of organic template molecules on substrates (molecular-templated ALD) is a promising technique for designing a molecular selectivity with thermal robustness onto the surfaces of metal oxides, which are required for heterogeneous catalysts and molecular sensing. However, self-aggregations of template molecules significantly impair the selectivity of the resulting molecules, which is difficult to prevent or observe. Here, a rational method is presented for uni-molecularly dispersing template molecules and revealing their state in the molecular-templated ALD process. The environment-sensitive fluorescence of pyrene is utilized as a probe to visualize the microenvironments around template molecules. The dispersion of pyrene moieties in OH-terminated SAMs allowed the pyrene molecules to be 1) covalently immobilized, 2) isolated from other pyrene molecules, and 3) surrounded by OH groups that act as ALD initiation sites. Systematic spectroscopic measurements of pyrene probes revealed the successful ALD of metal oxides surrounding template molecules without their undesired aggregations. Furthermore, emission enhancements are observed when Al2O3 is used as the surrounding metal oxide. The amplification of pyrene fluorescence intensity, lifetime, and quantum yield is attributed to the suppression of non-radiative decay, indicating that the Al2O3 layer has grown closely around a single organic molecule.

    DOI: 10.1002/admt.202401639

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  • All-<i>in Situ</i> Molecular-Templated Atomic Layer Deposition for Volatile Organic Compound Sensors

    Matsuo, H; Hosomi, T; Liu, JY; Saito, H; Tanaka, W; Takahashi, T; Yanagida, T

    ACS APPLIED NANO MATERIALS   7 ( 21 )   24498 - 24507   2024.10   eISSN:2574-0970

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    Publisher:ACS Applied Nano Materials  

    Molecular-templated atomic layer deposition (ALD) is defined as a deposition process in the presence of target molecules on surfaces. The resulting nanocavities after removal of the template molecules have unique molecular recognition abilities and are promising for various applications, including volatile organic compound sensors. However, few studies have investigated the nanocavity formation process, mainly due to its complexity. In particular, the complicated reconstructions of metal oxide surfaces in solution-phase processes have hindered facile control of the molecular template formation process. Here, we developed a molecular-templated ALD system performed entirely in the gas phase. The key to this system is a QCM chip covered by a metal oxide (ZnO) nanowire array, which amplifies the QCM signals to enable minute amounts of molecular monitoring. The suppression of metal oxide (TiO2) deposition in the ALD low cycle region (less than 20 cycles) was confirmed by QCM, indicating that the molecule significantly affects the formation of metal oxide nanosurfaces. The effect of the template molecule on the nanosurface formation in this region was also suggested by scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). Furthermore, the molecular capture ability after removing the template molecule was investigated by exposure to hexanal vapor. The amount of molecular adsorption was dependent on the ALD cycle number, with the highest value obtained near the cycle number, where the template molecule influenced the ALD growth mode. These results suggest that TiO2 grew around the template molecule to form a nanostructure influenced by the presence of the molecule, enhancing its ability to capture molecules of similar size as the template molecules. The technology developed in this study is expected to pave the way for the development of molecular sensors that can selectively adsorb and detect specific substances in gas mixtures.

    DOI: 10.1021/acsanm.4c03810

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  • High-fidelity phase-field simulation of solid-state sintering enabled by Bayesian data assimilation using in situ electron tomography data

    Ishii, A; Yamanaka, A; Yoshinaga, M; Sato, S; Ikeuchi, M; Saito, H; Hata, S; Yamamoto, A

    ACTA MATERIALIA   278   2024.10   ISSN:1359-6454 eISSN:1873-2453

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    Publisher:Acta Materialia  

    Experimental observation methods for understanding industrially important solid-state sintering are essential for the development of new materials and devices. To experimentally characterize solid-state sintering, the limitations posed by the complexity of target materials, experimental equipment, and observation conditions must be overcome. Therefore, hybrid techniques for predicting sintering behavior based on experimental datasets and physics-based simulation models are highly sought after. Herein, we propose a new technique for combining a physics-based model and experimental observation results from solid-state sintering using a nonsequential Bayesian data assimilation (DA) method. The proposed technique assimilates experimental data—obtained using in situ electron tomography/scanning transmission electron microscopy—into the corresponding phase-field (PF) model to enable high-fidelity PF simulations by estimating multiple material parameters included in the PF model. This study demonstrates the inverse estimation of seven parameters, including temperature-dependent diffusion coefficients, from the time-series information on the morphology of sintered nanoparticles observed in situ. The estimated parameters provide the high-fidelity PF simulation to capture the observed solid-state sintering of copper nanoparticles. Thus, this study contributes to the construction of digital twins for solid-state sintering based on DA-integrated PF simulations and in situ observation datasets and deepens our understanding of the sintering process.

    DOI: 10.1016/j.actamat.2024.120251

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  • Microscopic slickenside as a record of weak shock metamorphism in the surface layer of asteroid Ryugu

    Miyahara, M; Noguchi, T; Matsumoto, T; Tomioka, N; Miyake, A; Igami, Y; Seto, Y; Haruta, M; Saito, H; Hata, S; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Leroux, H; Le Guillou, C; Jacob, D; de la Peña, F; Laforet, S; Mouloud, BE; Marinova, M; Langenhorst, F; Harries, D; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, SI; Tsuda, Y

    METEORITICS & PLANETARY SCIENCE   59 ( 12 )   3181 - 3192   2024.9   ISSN:1086-9379 eISSN:1945-5100

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    Publisher:Meteoritics and Planetary Science  

    The surface morphology of regolith grains from the C-type asteroid Ryugu was studied in search of evidence of impact events on the asteroid. Scanning electron microscopy revealed that ~8% of C0105-042 Ryugu grains have a smooth surface on one side of the grains. One of these grains has striated linear grooves (striations) on its smooth surface. Transmission electron microscopy of the grain showed that a porous fine-grained Mg-Fe phyllosilicate assemblage, which is the main component of Ryugu grains, is compacted near the smooth surface. The smooth surface with striations closely resembles a slickenside, a characteristic texture found in terrestrial fault rocks formed by shear deformation. There is no evidence of melting/decomposition in the Mg-Fe phyllosilicates near the smooth surface, indicating that the shear heating temperature is less than ~1100 K. Assuming that the average length of the striations corresponds to the minimum displacement of the micro-fault, the shock pressure recorded in the C0105-042 Ryugu grain is estimated to be <~4.5 GPa by a fault mechanics calculation. The shock pressures of C0105-042, together with those of C0014 (~2 GPa) and C0055 (>~3.9 GPa) in previous studies suggest that the impact velocities recorded in these grains are < ~0.89–1.63 km s−1. Based on the impact velocities, these grains may record an impact event that occurred when asteroid Ryugu was in the orbit in Main Belt.

    DOI: 10.1111/maps.14271

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  • Deep-Learning-Assisted Rapid STEM and Its Application to Tomography Observation

    Saito Hikaru, Ihara Shiro, Hata Satoshi, Murayama Mitsuhiro

    KENBIKYO   59 ( 2 )   52 - 56   2024.8   ISSN:13490958 eISSN:24342386

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    Language:Japanese   Publisher:The Japanese Society of Microscopy  

    <p>Scanning transmission electron microscopy (STEM) is more suitable for visualizing the internal structure of thick samples compared to conventional transmission electron microscopy whose resolution is limited by the chromatic aberration of the imaging lens system, and it is often used for three-dimensional structural analysis using electron tomography. However, STEM image quality is seriously degraded by noise and artifacts, especially when pursuing rapid imaging on the order of milliseconds per frame or faster. In this paper, we report that deep learning-based denoising is effective for rapid STEM imaging, and can be applicable to rapid STEM tomography. By acquiring tilt-series images in just 5 seconds, the three-dimensional dislocation arrangement in a thick (300 nm) steel sample can be determined with sufficient accuracy. This method has enormous potential on improving in-situ or operando observation of samples in relatively thick media including liquid cells.</p>

    DOI: 10.11410/kenbikyo.59.2_52

    CiNii Research

  • High tolerance of the superconducting current to large grain boundary angles in potassium-doped BaFe<sub>2</sub>As<sub>2</sub>

    Hatano, T; Qin, DY; Iida, K; Gao, HY; Guo, ZM; Saito, H; Hata, S; Shimada, Y; Naito, M; Yamamoto, A

    NPG ASIA MATERIALS   16 ( 1 )   2024.8   ISSN:1884-4049 eISSN:1884-4057

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    Publisher:NPG Asia Materials  

    Superconducting magnets based on high-temperature superconductors (HTSs) have become critical components in cutting-edge technologies such as advanced medical applications. In HTSs, weak links of superconductivity are inevitable at high-angle grain boundaries (GBs). Thus, two adjacent grains should be crystallographically aligned within the critical angle (θc), for which the intergrain critical current density (Jc) starts to decrease exponentially. The θc of several iron-based superconductors (IBSs) is larger than that of cuprates. However, the decreases in both θc and intergrain Jc under magnetic fields for IBSs are still substantial, hampering their applications in polycrystalline forms. Here, we report that potassium-doped BaFe2As2 (Ba122:K) exhibits superior GB performance to that of previously reported IBSs. A transport Jc of over 0.1 MA/cm2 across [001]-tilt GBs with misorientation angles up to θGB = 24° was recorded even at 28 K, which is a required level for practical applications. Additionally, even in an applied magnetic field, θc was unaltered, and the decay of the intergrain Jc was small. Our results highlight the exceptional potential of Ba122:K for polycrystalline applications and pave the way for next-generation superconducting magnets.

    DOI: 10.1038/s41427-024-00561-9

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  • Electron microscopy observations of the diversity of Ryugu organic matter and its relationship to minerals at the micro- to nano-scale

    Stroud R.M., Barosch J., Bonal L., Burgess K., Cody G.D., De Gregorio B.T., Daly L., Dartois E., Dobrică E., Duprat J., Engrand C., Harries D., Hashiguchi M., Ishii H., Kebukawa Y., Kilcoyne A.D., Langenhorst F., Lee M.R., Nittler L.R., Quirico E., Okumura T., Remusat L., Sandford S., Yabuta H., Abe M., Abreu N.M., Bagot P.A.J., Beck P., Bejach L., Bland P.A., Bridges J.C., Cymes B.A., Dazzi A., de la Peña F., Deniset-Besseau A., Enju S., Enokido Y., Frank D.R., Gray J., Haruta M., Hata S., Hicks L., Igami Y., Jacob D., Kamide K., Komatsu M., Laforet S., Leroux H., Le Guillou C., Martins Z., Marinova M., Martinez J., Mathurin J., Matsumoto M., Matsumoto T., Matsuno J., McFadzean S., Michikami T., Mitsukawa I., Miyake A., Miyahara M., Miyazaki A., Montagnac G., Mostefaoui S., Nakamura T., Nakato A., Naraoka H., Nakauchi Y., Nakazawa S., Nishimura M., Noguchi T., Ohtaki K., Ohigashi T., Okada T., Okumura S., Okazaki R., Phan T.H.V., Rebois R., Sakamoto K., Saiki T., Saito H., Seto Y., Shigenaka M., Smith W., Suga H., Sun M., Tachibana S., Takahashi Y., Takeichi Y., Takeuchi A., Takigawa A., Tamenori Y., Tanaka S., Terui F., Thompson M.S., Tomioka N., Tsuchiyama A., Tsuda Y., Uesugi K., Uesugi M.

    Meteoritics and Planetary Science   59 ( 8 )   2023 - 2043   2024.8   ISSN:10869379

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    Publisher:Meteoritics and Planetary Science  

    Transmission electron microscopy analyses of Hayabusa2 samples show that Ryugu organic matter exhibits a range of morphologies, elemental compositions, and carbon functional chemistries consistent with those of carbonaceous chondrites that have experienced low-temperature aqueous alteration. Both nanoglobules and diffuse organic matter are abundant. Non-globular organic particles are also present, and including some that contain nanodiamond clusters. Diffuse organic matter is finely distributed in and around phyllosilicates, forms coatings on other minerals, and is also preserved in vesicles in secondary minerals such as carbonate and pyrrhotite. The average elemental compositions determined by energy-dispersive spectroscopy of extracted, demineralized insoluble organic matter samples A0107 and C0106 are C100N3O9S1 and C100N3O7S1, respectively, with the difference in O/C slightly outside the difference in the standard error of the mean. The functional chemistry of the nanoglobules varies from mostly aromatic C=C to mixtures of aromatic C=C, ketone C=O, aliphatic (CHn), and carboxyl (COOH) groups. Diffuse organic matter associated with phyllosilicates has variable aromatic C, ketone and carboxyl groups, and some localized aliphatics, but is dominated by molecular carbonate (CO3) absorption, comparable to prior observations of clay-bound organic matter in CI meteorites.

    DOI: 10.1111/maps.14128

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  • Phyllosilicates with embedded Fe-based nanophases in Ryugu and Orgueil

    Leroux, H; Le Guillou, C; Marinova, M; Laforet, S; Viennet, JC; Mouloud, BE; Teurtrie, A; de la Peña, F; Jacob, D; Hallatt, D; Fernandez, MP; Troadec, D; Noguchi, T; Matsumoto, T; Miyake, A; Igami, Y; Haruta, M; Saito, H; Hata, S; Seto, Y; Miyahara, M; Tomioka, N; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Langenhorst, F; Harries, D; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, SI; Tsuda, Y

    METEORITICS & PLANETARY SCIENCE   59 ( 8 )   1947 - 1965   2024.8   ISSN:1086-9379 eISSN:1945-5100

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    Publisher:Meteoritics and Planetary Science  

    Samples were recently collected from the carbonaceous asteroid (162173) Ryugu, by the Japan Aerospace Exploration Agency (JAXA) Hayabusa2 mission. They resemble CI chondrites material, thus showing clear evidence of extensive aqueous alteration attested by the widespread presence of a mixture of serpentine and saponite. We present here a scanning transmission electron microscopy study of the Ryugu dominant lithology of the phyllosilicate matrix at the nanometer scale, which we compare with that of the Orgueil CI chondrite. In both objects, the phyllosilicates are of comparable nature and texture, consisting of a mixture of small-sized crystallites of serpentine and saponite. At the micrometer scale or less, the texture is an alternation of fine and coarse domains. The fine-grained regions are dominated by saponite. In Ryugu, they enclose numerous Fe,Ni nanosulfides, whereas in Orgueil, S- and Ni-rich ferrihydrite is abundant. The coarse-grained regions contain more serpentine and no or little Fe,Ni sulfides or ferrihydrite. Scanning transmission x-ray microscopy at the Fe-L3 edge also reveals that iron valency of phyllosilicates is higher and more homogeneous in Orgueil (~70% Fe3+) than in Ryugu (<50% Fe3+). We interpret the observed textures as being mostly a consequence of aqueous alteration, likely resulting from the replacement by phyllosilicates of submicrometric components, initially agglomerated by a primary accretion. The fine-grained domains may result from the replacement of GEMS (GEMS—glass with embedded metal and sulfides) objects or from other types of nanometric assemblages of silicate and Fe-based nanophases. On the other hand, the coarse-grained regions may correspond to the replacement of anhydrous crystalline silicates of the olivine and pyroxene type. The major difference is the presence of Fe,Ni sulfides in Ryugu and of ferrihydrite and higher iron valency of phyllosilicates in Orgueil. This might be due to long-term terrestrial weathering that would have destabilized the nanosulfides. We also explore an alternative scenario involving more oxidizing hydrothermal conditions on the Orgueil parent body.

    DOI: 10.1111/maps.14101

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  • Incipient space weathering on asteroid 162173 Ryugu recorded by pyrrhotite

    Harries, D; Matsumoto, T; Langenhorst, F; Noguchi, T; Miyake, A; Igami, Y; Haruta, M; Seto, Y; Miyahara, M; Tomioka, N; Saito, H; Hata, S; Takigawa, A; Nakauchi, Y; Tachibana, S; Nakamura, T; Matsumoto, M; Ishii, HA; Bradley, JP; Ohtaki, K; Dobrica, E; Leroux, H; Le Guillou, C; Jacob, D; de la Pena, F; Laforet, S; Mouloud, BE; Marinova, M; Beck, P; Phan, VH; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Michikami, T; Yurimoto, H; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, SI; Tsuda, Y

    METEORITICS & PLANETARY SCIENCE   59 ( 8 )   2134 - 2148   2024.5   ISSN:1086-9379 eISSN:1945-5100

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    Publisher:Meteoritics and Planetary Science  

    Regolith samples returned from asteroid 162173 Ryugu by the Hayabusa2 mission provide direct means to study how space weathering operates on the surfaces of hydrous asteroids. The mechanisms of space weathering, its effects on mineral surfaces, and the characteristic time scales on which alteration occurs are central to understanding the spectroscopic properties and the taxonomy of asteroids in the solar system. Here, we investigate the behavior of the iron monosulfides mineral pyrrhotite (Fe1−xS) at the earliest stages of space weathering. Using electron microscopy methods, we identified a partially exposed pyrrhotite crystal that morphologically shows evidence for mass loss due to exposure to solar wind ion irradiation. We find that crystallographic changes to the pyrrhotite can be related to sulfur loss from its space-exposed surface and the diffusive redistribution of resulting excess iron into the interior of the crystal. Diffusion profiles allow us to estimate an order of magnitude of the exposure time of a few thousand years consistent with previous estimates of space exposure. During this interval, the adjacent phyllosilicates did not acquire discernable damage, suggesting that they are less susceptible to alteration by ion irradiation than pyrrhotite.

    DOI: 10.1111/maps.14176

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  • <i>In-situ</i> heating-and-electron tomography for materials research: from 3D (<i>in-situ</i> 2D) to 4D (<i>in-situ</i> 3D)

    Satoshi Hata, Shiro Ihara, Hikaru Saito, Mitsuhiro Murayama

    Microscopy   73 ( 2 )   133 - 144   2024.4   ISSN:2050-5698 eISSN:2050-5701

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    Abstract

    In-situ observation has expanded the application of transmission electron microscopy (TEM) and has made a significant contribution to materials research and development for energy, biomedical, quantum, etc. Recent technological developments related to in-situ TEM have empowered the incorporation of three-dimensional observation, which was previously considered incompatible. In this review article, we take up heating as the most commonly used external stimulus for in-situ TEM observation and overview recent in-situ TEM studies. Then, we focus on the electron tomography (ET) and in-situ heating combined observation by introducing the authors’ recent research as an example. Assuming that in-situ heating observation is expanded from two dimensions to three dimensions using a conventional TEM apparatus and a commercially available in-situ heating specimen holder, the following in-situ heating-and-ET observation procedure is proposed: (i) use a rapid heating-and-cooling function of a micro-electro-mechanical system holder; (ii) heat and cool the specimen intermittently and (iii) acquire a tilt-series dataset when the specimen heating is stopped. This procedure is not too technically challenging and can have a wide range of applications. Essential technical points for a successful 4D (space and time) observation will be discussed through reviewing the authors’ example application.

    DOI: 10.1093/jmicro/dfae008

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  • Diffusion-Dominated Luminescence Dynamics of CsPbBr<sub>3</sub> Studied Using Cathodoluminescence and Microphotoluminescence Spectroscopy

    Sho Nekita, Sotatsu Yanagimoto, Takumi Sannomiya, Keiichirou Akiba, Masato Takiguchi, Hisashi Sumikura, Itsuki Takagi, Kazutaka G. Nakamura, SenPo Yip, You Meng, Johnny C. Ho, Tetsuya Okuyama, Mitsuhiro Murayama, Hikaru Saito

    Nano Letters   24 ( 13 )   3971 - 3977   2024.3   ISSN:1530-6984 eISSN:1530-6992

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    DOI: 10.1021/acs.nanolett.4c00483

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  • A thiomolybdate cluster for visible-light-driven hydrogen evolution: comparison of homogeneous and heterogeneous approaches

    Batool, S; Schubert, JS; Ayala, P; Saito, H; Sampaio, MJ; Da Silva, ES; Silva, CG; Faria, JL; Eder, D; Cherevan, A

    SUSTAINABLE ENERGY & FUELS   8 ( 6 )   1225 - 1235   2024.3   ISSN:2398-4902

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    This study investigates the hydrogen evolution reaction (HER) efficiency of two photosystems incorporating an all-inorganic molecular thiomolybdate [Mo3S13]2− cluster as a HER catalyst. First, we delve into the performance of a homogeneous [Mo3S13]2−/[Ru(bpy)3]2+ (Mo3/Ru) dyad which demonstrates high turnover frequencies (TOFs) and apparent quantum yields (AQYs) at 445 nm approaching the level of 0.5%, yet its performance is marked by pronounced deactivation. In contrast, a heterogeneous approach involves anchoring [Mo3S13]2− onto graphitic carbon nitride (GCN) nanosheets through weak electrostatic association with its triazine/heptazine scaffold. [Mo3S13]2−/GCN (Mo3/GCN) displays effective H2 generation under visible light, with TOF metrics on par with those of its homogeneous analog. Although substantial leaching of [Mo3S13]2− species from the Mo3/GCN surface occurs, the remaining {Mo3}-based centers demonstrate impressive stability, leading to enduring HER performance, starkly distinguishing it from the homogeneous Mo3/Ru photosystem. Photoluminescence (PL) quenching experiments confirm that the performance of Mo3/GCN is not limited by the quality of the inorganic interface, but could be optimized by using higher surface area supports or a higher concentration of [Mo3S13]2− sites. Our findings showcase complexities underlying the evaluation and comparison of photosystems comprising well-defined catalytic centers and pave the way for developing analogous surface-supported (photo)catalysts with broad use in energy applications.

    DOI: 10.1039/d3se01658g

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  • Influx of nitrogen-rich material from the outer Solar System indicated by iron nitride in Ryugu samples Reviewed International journal

    Nature Astronomy   8 ( 2 )   207 - 215   2024.2

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  • In-situ heating-and-electron tomography for materials research: from 3D (in-situ 2D) to 4D (in-situ 3D) Invited Reviewed International journal

    Satoshi Hata, Shiro Ihara, Hikaru Saito, Mitsuhiro Murayama

    Microscopy   dfae008   2024.2

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  • A thiomolybdate cluster for visible-light-driven hydrogen evolution: comparison of homogeneous and heterogeneous approaches Invited Reviewed International journal

    Sustainable Energy & Fuels   8 ( 6 )   1225 - 1235   2024.2

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  • Influx of nitrogen-rich material from the outer Solar System indicated by iron nitride in Ryugu samples

    Matsumoto Toru, Noguchi Takaaki, Miyake Akira, Igami Yohei, Haruta Mitsutaka, Seto Yusuke, Miyahara Masaaki, Tomioka Naotaka, Saito Hikaru, Hata Satoshi, Harries Dennis, Takigawa Aki, Nakauchi Yusuke, Tachibana Shogo, Nakamura Tomoki, Matsumoto Megumi, Ishii Hope A., Bradley John P., Ohtaki Kenta, Dobrică Elena, Leroux Hugues, Le Guillou Corentin, Jacob Damien, de la Peña Francisco, Laforet Sylvain, Marinova Maya, Langenhorst Falko, Beck Pierre, Phan Thi H. V., Rebois Rolando, Abreu Neyda M., Gray Jennifer, Zega Thomas, Zanetta Pierre-M., Thompson Michelle S., Stroud Rhonda, Burgess Kate, Cymes Brittany A., Bridges John C., Hicks Leon, Lee Martin R., Daly Luke, Bland Phil A., Zolensky Michael E., Frank David R., Martinez James, Tsuchiyama Akira, Yasutake Masahiro, Matsuno Junya, Okumura Shota, Mitsukawa Itaru, Uesugi Kentaro, Uesugi Masayuki, Takeuchi Akihisa, Sun Mingqi, Enju Satomi, Michikami Tatsuhiro, Yurimoto Hisayoshi, Okazaki Ryuji, Yabuta Hikaru, Naraoka Hiroshi, Sakamoto Kanako, Yada Toru, Nishimura Masahiro, Nakato Aiko, Miyazaki Akiko, Yogata Kasumi, Abe Masanao, Okada Tatsuaki, Usui Tomohiro, Yoshikawa Makoto, Saiki Takanao, Tanaka Satoshi, Terui Fuyuto, Nakazawa Satoru, Watanabe Sei-ichiro, Tsuda Yuichi

    Nature Astronomy   8 ( 2 )   207 - 215   2024.2   eISSN:23973366

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    Large amounts of nitrogen compounds, such as ammonium salts, may be stored in icy bodies and comets, but the transport of these nitrogen-bearing solids into the near-Earth region is not well understood. Here, we report the discovery of iron nitride on magnetite grains from the surface of the near-Earth C-type carbonaceous asteroid Ryugu, suggesting inorganic nitrogen fixation. Micrometeoroid impacts and solar wind irradiation may have caused the selective loss of volatile species from major iron-bearing minerals to form the metallic iron. Iron nitride is a product of nitridation of the iron metal by impacts of micrometeoroids that have higher nitrogen contents than the CI chondrites. The impactors are probably primitive materials with origins in the nitrogen-rich reservoirs in the outer Solar System. Our observation implies that the amount of nitrogen available for planetary formation and prebiotic reactions in the inner Solar System is greater than previously recognized.

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  • Influx of nitrogen-rich material from the outer Solar System indicated by iron nitride in Ryugu samples

    Matsumoto, T; Noguchi, T; Miyake, A; Igami, Y; Haruta, M; Seto, Y; Miyahara, M; Tomioka, N; Saito, H; Hata, S; Harries, D; Takigawa, A; Nakauchi, Y; Tachibana, S; Nakamura, T; Matsumoto, M; Ishii, HA; Bradley, JP; Ohtaki, K; Dobrica, E; Leroux, H; Le Guillou, C; Jacob, D; de la Peña, F; Laforet, S; Marinova, M; Langenhorst, F; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Michikami, T; Yurimoto, H; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, S; Tsuda, Y

    NATURE ASTRONOMY   8 ( 2 )   207 - 215   2024.2   ISSN:2397-3366

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    Large amounts of nitrogen compounds, such as ammonium salts, may be stored in icy bodies and comets, but the transport of these nitrogen-bearing solids into the near-Earth region is not well understood. Here, we report the discovery of iron nitride on magnetite grains from the surface of the near-Earth C-type carbonaceous asteroid Ryugu, suggesting inorganic nitrogen fixation. Micrometeoroid impacts and solar wind irradiation may have caused the selective loss of volatile species from major iron-bearing minerals to form the metallic iron. Iron nitride is a product of nitridation of the iron metal by impacts of micrometeoroids that have higher nitrogen contents than the CI chondrites. The impactors are probably primitive materials with origins in the nitrogen-rich reservoirs in the outer Solar System. Our observation implies that the amount of nitrogen available for planetary formation and prebiotic reactions in the inner Solar System is greater than previously recognized.

    DOI: 10.1038/s41550-023-02137-z

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  • In situ investigation of an organic micro-globule and its mineralogical context within a Ryugu "sand" grain

    Phan, VH; Beck, P; Rebois, R; Quirico, E; Noguchi, T; Matsumoto, T; Miyake, A; Igami, Y; Haruta, M; Saito, H; Hata, S; Seto, Y; Miyahara, M; Tomioka, N; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Leroux, H; Le Guillou, C; Jacob, D; de la Pena, F; Laforet, S; Marinova, M; Langenhorst, F; Harries, D; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Mathurin, J; Dazzi, A; Dartois, E; Engrand, C; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Hoppe, P; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, SI; Tsuda, Y

    METEORITICS & PLANETARY SCIENCE   59 ( 8 )   1983 - 2001   2024.1   ISSN:1086-9379 eISSN:1945-5100

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    The Hayabusa2 mission from the Japan Aerospace Exploration Agency (JAXA) returned to the Earth samples of carbonaceous asteroid (162173) Ryugu. This mission offers a unique opportunity to investigate in the laboratory samples from a C-type asteroid, without physical or chemical alteration by the terrestrial atmosphere. Here, we report on an investigation of the mineralogy and the organo-chemistry of Hayabusa2 samples using a combination of micro- and nano-infrared spectroscopy. Particles investigated with conventional FTIR spectroscopy have spectra dominated by phyllosilicate-related absorption, as observed for samples of CI-chondrites, selected ungrouped carbonaceous chondrites, and selected hydrated micrometeorites. Ryugu samples show smaller sulfate-related absorption than CI-chondrites. Our samples that were only briefly exposed to the Earth atmosphere show absorptions related to molecular water, revealing fast terrestrial contamination of the spectral signature at 3 μm. Overall, our FTIR data are in agreement with other work done on Ryugu samples, revealing a low degree of mineralogical variability across Ryugu samples. AFM-IR mapping of the grains shows the presence of a micrometer-sized organic globule in one of our analyzed grains. The AFM-IR spectra obtained on this globule are similar to IR spectra obtained on IOM suggesting that it is constituted of refractory organic matter. This globule may host silicate in its interior, with a different mineralogy than bulk Ryugu phyllosilicate. The shape, presence of peculiar silicate, and the nature of organic constituting the globule point toward a pre-accretionary origin of this globule and that at least part of Ryugu organics were inherited from the protosolar nebulae or the interstellar media. Altogether, our results show the similarities between Ryugu samples and CI chondrites.

    DOI: 10.1111/maps.14122

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  • Four-dimensional-STEM analysis of the phyllosilicate-rich matrix of Ryugu samples

    Mouloud, BE; Jacob, D; de la Peña, F; Marinova, M; Le Guillou, C; Viennet, JC; Laforet, S; Leroux, H; Teurtrie, A; Noguchi, T; Matsumoto, T; Miyake, A; Igami, Y; Haruta, M; Saito, H; Hata, S; Seto, Y; Miyahara, M; Tomioka, N; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Langenhorst, F; Harries, D; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, S; Tsuda, Y

    METEORITICS & PLANETARY SCIENCE   59 ( 8 )   2002 - 2022   2024.1   ISSN:1086-9379 eISSN:1945-5100

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    Ryugu asteroid grains brought back to the Earth by the Hayabusa2 space mission are pristine samples containing hydrated minerals and organic compounds. Here, we investigate the mineralogy of their phyllosilicate-rich matrix with four-dimensional scanning transmission electron microscopy (4D-STEM). We have identified and mapped the mineral phases at the nanometer scale (serpentine, smectite, pyrrhotite), observed the presence of Ni-bearing pyrrhotite, and identified the serpentine polymorph as lizardite, in agreement with the reported aqueous alteration history of Ryugu. Furthermore, we have mapped the d-spacings of smectite and observed a broad distribution of values, ranging from 1 to 2 nm, with an average d-spacing of 1.24 nm, indicating significant heterogeneity within the sample. Such d-spacing variability could be the result of either the presence of organic matter trapped in the interlayers or the influence of various geochemical conditions at the submicrometer scale, suggestive of a range of organic compounds and/or changes in smectite crystal chemistry.

    DOI: 10.1111/maps.14124

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  • Cathodoluminescence spectral and lifetime mapping of Cs<sub>4</sub>PbBr<sub>6</sub>: fast lifetime and its scintillator application

    Kubota, T; Yanagimoto, S; Saito, H; Akiba, K; Ishii, A; Sannomiya, T

    APPLIED PHYSICS EXPRESS   17 ( 1 )   2024.1   ISSN:1882-0778 eISSN:1882-0786

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    Highly efficient green emission of Cs4PbBr6 has been attributed to intermediate states formed by embedded CsPbBr3 nanocrystals or defects. However, direct experimental confirmation of the presence of such nano-emitters is not straightforward and the emission mechanism remains elusive. By using cathodoluminescence (CL) imaging with a high spatial resolution, we demonstrate that CsPbBr3 nanocrystals within the Cs4PbBr6 matrix contribute to the green emission, exhibiting optical behavior distinct from the matrix. Additionally, we explore its potential as an electron beam scintillator, given its high CL intensity and exceptionally short lifetime.

    DOI: 10.35848/1882-0786/ad1bc4

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  • Cathodoluminescence spectral and lifetime mapping of Cs4PbBr6: fast lifetime and its scintillator application Reviewed International journal

    Tetsuya Kubota, Sotatsu Yanagimoto, Hikaru Saito, Keiichirou Akiba, Ayumi Ishii, Takumi Sannomiya

    Applied Physics Express   17 ( 1 )   015005   2024.1

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  • Four‐dimensional‐STEM analysis of the phyllosilicate‐rich matrix of Ryugu samples Reviewed International journal

    Bahae‐eddine Mouloud, Damien Jacob, Francisco de la Peña, Maya Marinova, Corentin Le Guillou, Jean‐christophe Viennet, Sylvain Laforet, Hugues Leroux, Adrien Teurtrie, Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A Ishii, John P Bradley, Kenta K Ohtaki, Elena Dobrica, Falko Langenhorst, Dennis Harries, Pierre Beck, Thi HV Phan, Rolando Rebois, Neyda M Abreu, Jennifer Gray, Thomas Zega, Pierre‐M Zanetta, Michelle S Thompson, Rhonda Stroud, Kate Burgess, Brittany A Cymes, John C Bridges, Leon Hicks, Martin R Lee, Luke Daly, Phil A Bland, Michael E Zolensky, David R Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tomohiro Usui, Toru Yada, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamotoa, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei‐ichiro Watanabe, Yuichi Tsuda

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  • In situ investigation of an organic micro‐globule and its mineralogical context within a Ryugu “sand” grain Reviewed International journal

    Van TH Phan, Pierre Beck, Rolando Rebois, Eric Quirico, Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A Ishii, John P Bradley, Kenta K Ohtaki, Elena Dobrică, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Maya Marinova, Falko Langenhorst, Dennis Harries, Neyda M Abreu, Jennifer Gray, Thomas Zega, Pierre‐M Zanetta, Michelle S Thompson, Rhonda Stroud, Jérémie Mathurin, Alexandre Dazzi, Emmanuel Dartois, Cécile Engrand, Kate Burgess, Brittany A Cymes, John C Bridges, Leon Hicks, Martin R Lee, Luke Daly, Phil A Bland, Michael E Zolensky, David R Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tomohiro Usui, Toru Yada, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamotoa, Peter Hoppe, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei‐ichiro Watanabe, Yuichi Tsuda

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  • Electron microscopy observations of the diversity of Ryugu organic matter and its relationship to minerals at the micro‐to nano‐scale Reviewed International journal

    Rhonda M Stroud, Jens Barosch, Lydie Bonal, Katherine Burgess, George D Cody, Bradley T De Gregorio, Luke Daly, Emmanuel Dartois, Elena Dobrică, Jean Duprat, Cecile Engrand, Dennis Harries, Minako Hashiguchi, Hope Ishii, Yoko Kebukawa, A David Kilcoyne, Falko Langenhorst, Martin R Lee, Larry R Nittler, Eric Quirico, Taiga Okumura, Laurent Remusat, Scott Sandford, Hikaru Yabuta, Masanao Abe, Neyda M Abreu, Paul AJ Bagot, Pierre Beck, Laure Bejach, Phil A Bland, John C Bridges, Brittany A Cymes, Alexandre Dazzi, Francisco de la Peña, Ariane Deniset‐Besseau, Satomi Enju, Yuma Enokido, David R Frank, Jennifer Gray, Mitsutaka Haruta, Satoshi Hata, Leon Hicks, Yohei Igami, Damien Jacob, Kanami Kamide, Mutsumi Komatsu, Sylvain Laforet, Hugues Leroux, Corentin Le Guillou, Zita Martins, Maya Marinova, James Martinez, Jérémie Mathurin, Megumi Matsumoto, Toru Matsumoto, Junya Matsuno, Samuel McFadzean, Tatsuhiro Michikami, Itaru Mitsukawa, Akira Miyake, Masaaki Miyahara, Akiko Miyazaki, Gilles Montagnac, Smail Mostefaoui, Tomoki Nakamura, Aiko Nakato, Hiroshi Naraoka, Yusuke Nakauchi, Satoru Nakazawa, Masahiro Nishimura, Takaaki Noguchi, Kenta Ohtaki, Takuji Ohigashi, Tatsuaki Okada, Shota Okumura, Ryuji Okazaki, Thi HV Phan, Rolando Rebois, Kanako Sakamoto, Takanao Saiki, Hikaru Saito, Yusuke Seto, Miho Shigenaka, William Smith, Hiroki Suga, Mingqi Sun, Shogo Tachibana, Yoshio Takahashi, Yasuo Takeichi, Akihisa Takeuchi, Aki Takigawa, Yusuke Tamenori, Satoshi Tanaka, Fuyuto Terui, Michelle S Thompson, Naotaka Tomioka, Akira Tsuchiyama, Yuichi Tsuda, Kentaro Uesugi, Masayuki Uesugi, Tomohiro Usui, Maximilien Verdier‐Paoletti, Daisuke Wakabayashi, Sei‐ichiro Watanabe, Toru Yada, Shohei Yamashita, Masahiro Yasutake, Kasumi Yogata, Makoto Yoshikawa, Hisayoshi Yurimoto, Pierre‐M Zanetta, Thomas Zega, Michael E Zolensky

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  • Effect of ZrSnO4 solid solution on the crystallization behavior of Li2O–Al2O3–SiO2 glasses Reviewed International journal

    15 ( 1 )   31 - 43   2024.1

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  • Effect of ZrSnO<sub>4</sub> solid solution on the crystallization behavior of Li<sub>2</sub>O-Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> glasses

    Kajihara, T; Hijiya, H; Yoshida, S; Ninomiya, K; Nishibori, M; Saito, H; Fujino, S; Hata, S

    INTERNATIONAL JOURNAL OF APPLIED GLASS SCIENCE   15 ( 1 )   31 - 43   2024.1   ISSN:2041-1286 eISSN:2041-1294

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    Herein, the crystallization behavior of a Li2O–Al2O3–SiO2 (LAS) glass system with the addition of ZrO2 and SnO2 as nucleating agents was investigated using X-ray diffraction, differential scanning calorimetry, four-dimensional scanning transmission electron microscopy, and X-ray absorption fine-structure measurements. At lower heat-treatment temperatures, the addition of ZrO2 and SnO2 afforded a ZrSnO4 solid solution (SS), whereas at higher heat-treatment temperatures, the ZrSnO4 SS decomposed, affording tetragonal ZrO2 and tetragonal SnO2. LAS-based crystalline phases, such as β-quartz and β-spodumene phases SS, were formed after the formation of the ZrSnO4 SS. ZrSnO4 SS particles a few nanometers in size were present in contact with the β-quartz SS particles a few dozen nanometers in size. This suggests that the ZrSnO4 SS served as a crystal nucleus for the β-quartz SS, promoting its growth.

    DOI: 10.1111/ijag.16644

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  • Three-dimensional in-situ observation of metal nanoparticle sintering by using transmission electron microscopy

    Ihara Shiro, Saito Hikaru, Hata Satoshi, Murayama Mitsuhiro

    Journal of the Japanese Association for Crystal Growth   51 ( 1 )   n/a   2024   ISSN:03856275 eISSN:21878366

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    Language:Japanese   Publisher:The Japanese Association for Crystal Growth  

    <p>  Metal nanoparticles undertake sintering at a lower temperature compared to their bulk counterparts, attracting great attention in industrial applications such as printed electronics. Since nanoparticles are easy to aggregate, the three-dimensional (3D) visualization of their sintering process plays a vital role in quantifying the morphological changes during heating. However, the nanoparticles are sensitive to surface contamination, resulting in poor affinity to the 3D visualization with conventional electron beam intensity because the visualization technique requires a long beam exposure time, potentially making beam induced contamination significant. In this paper, we demonstrate our developed 3D observation scheme, including advanced image processing techniques. A sample transfer system, which enables to prevent nanoparticles from being exposed to air, and an ultra-low-electron dose observation protocol prevents surface contamination during the observation. The low-signal-to-noise ratio of acquired images is compensated by the advanced image processing techniques. The obtained 3D images of nanoparticles enable to measure the neck growth and variation of particle distance in 3D during the sintering in a quantitative way.</p>

    DOI: 10.19009/jjacg.51-1-03

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  • Mineralogy and petrology of fine-grained samples recovered from the asteroid (162173) Ryugu

    Noguchi, T; Matsumoto, T; Miyake, A; Igami, Y; Haruta, M; Saito, H; Hata, S; Seto, Y; Miyahara, M; Tomioka, N; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Leroux, H; Le Guillou, C; Jacob, D; de la Peña, F; Laforet, S; Mouloud, BE; Marinova, M; Langenhorst, F; Harries, D; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Smith, WA; Mcfadzean, S; Martin, PE; Bagot, PAJ; Fougerouse, D; Saxey, DW; Reddy, S; Rickard, WDA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Hoppe, P; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, S; Tsuda, Y

    METEORITICS & PLANETARY SCIENCE   59 ( 8 )   1877 - 1906   2023.11   ISSN:1086-9379 eISSN:1945-5100

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    Samples returned from the carbonaceous asteroid (162173) Ryugu by the Hayabusa2 mission revealed that Ryugu is composed of materials consistent with CI chondrites and some types of space weathering. We report detailed mineralogy of the fine-grained Ryugu samples allocated to our “Sand” team and report additional space weathering features found on the grains. The dominant mineralogy is composed of a fine-grained mixture of Mg-rich saponite and serpentine, magnetite, pyrrhotite, pentlandite, dolomite, and Fe-bearing magnesite. These grains have mineralogy comparable to that of CI chondrites, showing severe aqueous alteration but lacking ferrihydrite and sulfate. These results are similar to previous works on large Ryugu grains. In addition to the major minerals, we also find many minerals that are rare or have not been reported among CI chondrites. Accessory minerals identified are hydroxyapatite, Mg-Na phosphate, olivine, low-Ca pyroxene, Mg-Al spinel, chromite, manganochromite, eskolaite, ilmenite, cubanite, polydymite, transjordanite, schreibersite, calcite, moissanite, and poorly crystalline phyllosilicate. We also show scanning transmission electron microscope and scanning electron microscope compositional maps and images of some space-weathered grains and severely heated and melted grains. Although our mineralogical results are consistent with that of millimeter-sized grains, the fine-grained fraction is best suited to investigate impact-induced space weathering.

    DOI: 10.1111/maps.14093

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  • Mineralogy and petrology of fine‐grained samples recovered from the asteroid (162173) Ryugu Reviewed International journal

    Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A Ishii, John P Bradley, Kenta K Ohtaki, Elena Dobrică, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Bahae‐Eddine Mouloud, Maya Marinova, Falko Langenhorst, Dennis Harries, Pierre Beck, Thi HV Phan, Rolando Rebois, Neyda M Abreu, Jennifer Gray, Thomas Zega, Pierre‐M Zanetta, Michelle S Thompson, Rhonda Stroud, Kate Burgess, Brittany A Cymes, John C Bridges, Leon Hicks, Martin R Lee, Luke Daly, Phil A Bland, William A Smith, Sam McFadzean, Pierre‐Etienne Martin, Paul AJ Bagot, Dennis Fougerouse, David W Saxey, Steven Reddy, William DA Rickard, Michael E Zolensky, David R Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tomohiro Usui, Toru Yada, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamotoa, Peter Hoppe, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei‐ichiro Watanabe, Yuichi Tsuda

    2023.11

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  • Phyllosilicates with embedded Fe‐based nanophases in Ryugu and Orgueil Invited Reviewed International journal

    Hugues Leroux, Corentin Le Guillou, Maya Marinova, Sylvain Laforet, Jean‐Christophe Viennet, Bahae‐eddine Mouloud, Adrien Teurtrie, Francisco de la Peña, Damien Jacob, Daniel Hallatt, Mario Pelaez Fernandez, David Troadec, Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A Ishii, John P Bradley, Kenta K Ohtaki, Elena Dobrică, Falko Langenhorst, Dennis Harries, Pierre Beck, Thi HV Phan, Rolando Rebois, Neyda M Abreu, Jennifer Gray, Thomas Zega, Pierre‐M Zanetta, Michelle S Thompson, Rhonda Stroud, Kate Burgess, Brittany A Cymes, John C Bridges, Leon Hicks, Martin R Lee, Luke Daly, Phil A Bland, Michael E Zolensky, David R Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tomohiro Usui, Toru Yada, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamotoa, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei‐Ichiro Watanabe, Yuichi Tsuda

    2023.11

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  • Time-correlated electron and photon counting microscopy

    Sotatsu Yanagimoto, Naoki Yamamoto, Tatsuro Yuge, Hikaru Saito, Keiichirou Akiba, Takumi Sannomiya

    Communications Physics   6 ( 1 )   2023.9   ISSN:2399-3650 eISSN:2399-3650

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    Abstract

    Electron microscopy based on high-energy electrons allows nanoscopic analytical imaging taking advantage of secondarily generated particles. Especially for cathodoluminescence, the correlation between primary incident electrons and emitted photons includes information on the entire interaction process. However, electron-photon time correlation tracking the relaxation dynamics of luminescent materials has so far not been achieved. In this work, we propose time-correlated electron and photon counting microscopy, where coincidence events of primary electrons and generated photons are counted after interaction. The electron-photon time correlation enables extracting a unique lifetime of the emitter independent of the photon state, accounting for coherent and incoherent photon generation processes. We also introduce a correlation factor and discuss the correlation between electrons and generated coherent photons. Through momentum selection, we observe correlation changes indicating the presence of pair correlation originated from the electron-photon entanglement. The present work lays the foundation for developing next-generation electron microscopy based on quantum correlation.

    DOI: 10.1038/s42005-023-01371-1

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  • Deep Learning Enabled High-Speed Scanning Transmission Electron Microscopy for In Situ and Three-Dimensional Observation

    IHARA Shiro, Saito Hikaru, MURAYAMA Mitsuhiro

    Journal of the Society of Materials Science, Japan   72 ( 9 )   631 - 637   2023.9   ISSN:05145163 eISSN:18807488

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    DOI: 10.2472/jsms.72.631

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  • Pseudobinary Approach to the Discovery and Design of Copper-Based Sulfides

    Takashi Hagiwara, Koichiro Suekuni, Pierric Lemoine, Carmelo Prestipino, Erik Elkaim, Andrew R. Supka, Rabih Al Rahal Al Orabi, Marco Fornari, Emmanuel Guilmeau, Bernard Raveau, Hikaru Saito, Philipp Sauerschnig, Michihiro Ohta, Yui Kanemori, Michitaka Ohtaki

    Chemistry of Materials   35 ( 18 )   7554 - 7563   2023.9   ISSN:0897-4756 eISSN:1520-5002

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    DOI: 10.1021/acs.chemmater.3c01135

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  • Time-correlated electron and photon counting microscopy Reviewed International journal

    Sotatsu Yanagimoto, Naoki Yamamoto, Tatsuro Yuge, Hikaru Saito, Keiichirou Akiba, Takumi Sannomiya

    Communications Physics   6 ( 1 )   260   2023.9

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  • Pseudobinary Approach to the Discovery and Design of Copper-Based Sulfides Reviewed International journal

    Takashi Hagiwara, Koichiro Suekuni, Pierric Lemoine, Carmelo Prestipino, Erik Elkaim, Andrew R Supka, Rabih Al Rahal Al Orabi, Marco Fornari, Emmanuel Guilmeau, Bernard Raveau, Hikaru Saito, Philipp Sauerschnig, Michihiro Ohta, Yui Kanemori, Michitaka Ohtaki

    Chemistry of Materials   35 ( 18 )   7554 - 7563   2023.9

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  • The Emergence of 2D Building Units in Metal‐Organic Frameworks for Photocatalytic Hydrogen Evolution: A Case Study with COK‐47 Reviewed International journal

    13 ( 31 )   2300961   2023.8

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  • Microstructure and Its Heat Treatment Process of Thin Films Fabricated by Alternate Sputtering of (Bi,Pb)<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>x</sub> and Pb-Ca-Cu-O Targets on SrTiO<sub>3</sub> Substrates

    Hata, S; Fukuda, D; Saito, H; Shimada, Y; Guo, ZM; Matsumoto, A; Nakashima, H; Kitaguchi, H

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   33 ( 5 )   2023.8   ISSN:1051-8223 eISSN:1558-2515

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    For obtaining microscopic knowledge toward a fabrication process of (Bi,Pb)2Sr2Ca2Cu3Ox (Bi,Pb-2223) single-phase material, we fabricated a multilayered film on a SrTiO3(001) substrate by a sputtering method using (Bi,Pb)2Sr2CaCu2Oy (Bi,Pb-2212) and Pb-Ca-Cu-O targets alternately at 650 °C. The as-grown film was an epitaxially grown multilayered film consisting of Bi,Pb-2212 and Pb-Ca-Cu-O layers. Coarse grains of impurity phases were also formed within the multilayered film, and these impurity phases were difficult to eliminate even after heat treatments. After 10 h heat treatment at 840 °C with Bi,Pb-2223 pellets, the phase transition from Bi,Pb-2212 to Bi,Pb-2223 occurred in the multilayered film. The phase transition to Bi,Pb-2223 proceeded preferentially at the interface with the impurity phases and the Pb-Ca-Cu-O layers. These observation results suggest that the impurity phases promote three-dimensional atomic diffusion in the multilayered film to accelerate the phase transition to Bi,Pb-2223, as well as consume constituent elements, Ca, Cu and O. Even after the 100 h heat treatment at 840 °C with Bi,Pb-2223 pellets, the phase transition from Bi,Pb-2212 to Bi,Pb-2223 did not proceed completely, and the fraction of the Bi,Pb-2223 phase in the whole superconducting phases was ∼50%. It is suggested that controlling the formation and microstructure of the impurity phases is a key to further increasing the fraction of the Bi,Pb-2223 phase.

    DOI: 10.1109/TASC.2023.3259920

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  • The Emergence of 2D Building Units in Metal-Organic Frameworks for Photocatalytic Hydrogen Evolution: A Case Study with COK-47

    Ayala, P; Naghdi, S; Nandan, SP; Myakala, SN; Rath, J; Saito, H; Guggenberger, P; Lakhanlal, L; Kleitz, F; Toroker, MC; Cherevan, A; Eder, D

    ADVANCED ENERGY MATERIALS   13 ( 31 )   2023.8   ISSN:1614-6832 eISSN:1614-6840

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    Metal-organic frameworks (MOFs) are promising materials for photocatalytic water splitting reactions, but examples of visible light-responsive, catalytically active, and stable MOFs are still rare. A detailed investigation is conducted for COK-47 – a recently described MOF comprising 2D Ti-O6 secondary building units (SBUs) – toward a photocatalytic hydrogen evolution reaction (HER), showing how overall particle morphology, surface area, and missing ligand defects are central parameters governing the material's ultimate performance. The newly synthesized COK-47ISO is among the most active MOFs to date, yielding HER-rates of 8.6 µmol h−1, and an apparent quantum yield (AQY) of 0.5% under visible light illumination. Optoelectronic and photoluminescence investigations, supported by theoretical calculations, enable the unraveling of its electronic structure along with charge transfer and recombination kinetics. A wavelength-dependent reaction mechanism is proposed involving ligand to metal charge transfer (LMCT) and the main challenges for visible or UV photoexcitation are identified, demonstrating that the unique 2D layered structure aids charge separation and is key to the high performance. This work introduces COK-47 as a promising alternative to the well-known MIL-125 family and offers directions for future studies.

    DOI: 10.1002/aenm.202300961

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  • In situ electron tomography for the thermally activated solid reaction of anaerobic nanoparticles Reviewed

    Shiro Ihara, Mizumo Yoshinaga, Hiroya Miyazaki, Kota Wada, Satoshi Hata, Hikaru Saito, Mitsuhiro Murayama

    Nanoscale   15 ( 23 )   10133 - 10140   2023.6   ISSN:2040-3364 eISSN:2040-3372

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  • Yield and flow properties of ultra-fine, fine, and coarse grain microstructures of FeCoNi equiatomic alloy at ambient and cryogenic temperatures Reviewed International journal

    Avala Lavakumar, Shuhei Yoshida, Jesada Punyafu, Shiro Ihara, Yan Chong, Hikaru Saito, Nobuhiro Tsuji, Mitsuhiro Murayama

    Scripta Materialia   2023.6

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  • In situ electron tomography for the thermally activated solid reaction of anaerobic nanoparticles Reviewed International journal

    Shiro Ihara, Mizumo Yoshinaga, Hiroya Miyazaki, Kota Wada, Satoshi Hata, Hikaru Saito, Mitsuhiro Murayama

    Nanoscale   15   10133 - 10140   2023.6

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  • Yield and flow properties of ultra-fine, fine, and coarse grain microstructures of FeCoNi equiatomic alloy at ambient and cryogenic temperatures

    Avala Lavakumar, Shuhei Yoshida, Jesada Punyafu, Shiro Ihara, Yan Chong, Hikaru Saito, Nobuhiro Tsuji, Mitsuhiro Murayama

    Scripta Materialia   230   115392 - 115392   2023.6   ISSN:1359-6462 eISSN:1872-8456

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    DOI: 10.1016/j.scriptamat.2023.115392

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  • Interfacial Molecular Compatibility for Programming Organic-Metal Oxide Superlattices

    Ono, T; Mitamura, S; Hosomi, T; Saito, H; Ikeuchi, M; Liu, JY; Nagashima, K; Takahashi, T; Tanaka, W; Kanai, M; Yanagida, T

    ACS APPLIED MATERIALS & INTERFACES   15 ( 22 )   27099 - 27109   2023.5   ISSN:1944-8244 eISSN:1944-8252

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    Artificially programming a sequence of organic-metal oxide multilayers (superlattices) by using atomic layer deposition (ALD) is a fascinating and challenging issue in material chemistry. However, the complex chemical reactions between ALD precursors and organic layer surfaces have limited their applications for various material combinations. Here, we demonstrate the impact of interfacial molecular compatibility on the formation of organic-metal oxide superlattices using ALD. The effects of both organic and inorganic compositions on the metal oxide layer formation processes onto self-assembled monolayers (SAM) were examined by using scanning transmission electron microscopy, in situ quartz crystal microbalance measurements, and Fourier-transformed infrared spectroscopy. These series of experiments reveal that the terminal group of organic SAM molecules must satisfy two conflicting requirements, the first of which is to promptly react with ALD precursors and the second is not to bind strongly to the bottom metal oxide layers to avoid undesired SAM conformations. OH-terminated phosphate aliphatic molecules, which we have synthesized, were identified as one of the best candidates for such a purpose. Molecular compatibility between metal oxide precursors and the −OHs must be properly considered to form superlattices. In addition, it is also important to form densely packed and all-trans-like SAMs to maximize the surface density of reactive −OHs on the SAMs. Based on these design strategies for organic-metal oxide superlattices, we have successfully fabricated various superlattices composed of metal oxides (Al-, Hf-, Mg-, Sn-, Ti-, and Zr oxides) and their multilayered structures.

    DOI: 10.1021/acsami.3c04470

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  • Three-dimensional electron tomography and recent expansion of its applications in materials science

    Norio Baba, Satoshi Hata, Hikaru Saito, Kenji Kaneko

    Microscopy   72 ( 2 )   111 - 134   2023.4   ISSN:2050-5698 eISSN:2050-5701

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    Electron tomography (ET) is a powerful tool for elucidating the properties and functionalities of materials. The innovative development of aberration-corrected electron microscopy in the early 21st century and the remarkable progress in the development of detectors, equipment and devices related to ET have resulted in substantial improvements in resolution. However, not only advances in hardware but also remarkable developments in reconstruction algorithms and related three-dimensional (3D) analysis methods have contributed to the resolution improvements. ET has its own problems, including the missing-wedge problem due to the limited tilt-angle range and the need to acquire numerous specimen-tilt images, the latter of which is time-consuming and can potentially damage the specimen. This review paper aims to (i) describe the established basic theories and definitions regarding 3D resolution of ET and practical 3D resolution measurement methods, (ii) discuss various reconstruction algorithms that effectively overcome the aforementioned problems and (iii) describe recent progress in the core of ET applications in materials science with respect to atomic ET, analytical ET and in-situ ET. The aforementioned ET problems have been addressed with each method developed in each field of application. Notably, in terms of aim (ii), recently developed reconstruction algorithms can reduce the number of projection images (specimen-tilt images) needed to attain a certain resolution without violating the Nyquist criterion. This approach is interpreted as a novel non-linear sampling theorem.

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  • Nonequilibrium spherulitic magnetite in the Ryugu samples

    Dobrica, E; Ishii, HA; Bradley, JP; Ohtaki, K; Brearley, AJ; Noguchi, T; Matsumoto, T; Miyake, A; Igami, Y; Haruta, M; Saito, H; Hata, S; Seto, Y; Miyahara, M; Tomioka, N; Leroux, H; Le Guillou, C; Jacob, D; Pena, FD; Laforet, S; Marinova, M; Langenhorst, F; Harries, D; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Yurimoto, H; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, S; Tsuda, Y

    GEOCHIMICA ET COSMOCHIMICA ACTA   346   65 - 75   2023.4   ISSN:0016-7037 eISSN:1872-9533

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    We have investigated several particles collected during each of two touchdowns of the Hayabusa2 spacecraft at the surface of the C-type asteroid 162173 Ryugu using various electron microscope techniques. Our detailed transmission electron microscopy study shows the presence of magnetite with various morphologies coexisting in close proximity. This is characteristic of CI chondrite-like materials and consistent with the mineral assemblages and compositions in the Ryugu parent body. We describe the microstructural characteristics of magnetite with different morphologies, which could have resulted from the chemical conditions (growth vs. diffusion rate) during their formation. Furthermore, we describe the presence of magnetites with a spherulitic structure composed of individual radiating fibers that are characterized by pervasive, homogeneously distributed euhedral to subhedral pores that have not been described in previous chondrite studies. This particular spherulitic structure is consistent with crystallization under nonequilibrium conditions. Additionally, the presence of a high density of defects within the magnetite fibers, the high surface/volume ratio of this morphology, and the presence of amorphous materials in several pores and at the edges of the acicular fibers further support their formation under nonequilibrium conditions. We suggest that the growth processes that lead to this structure result from the solution reaching a supersaturated state, resulting in an adjustment to a lower free energy condition via nucleation and rapid growth.

    DOI: 10.1016/j.gca.2023.02.003

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  • Nonequilibrium spherulitic magnetite in the Ryugu samples Reviewed International journal

    Geochimica et Cosmochimica Acta   346 ( 65-75 )   2023.4

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  • Three-dimensional electron tomography and recent expansion of its applications in materials science Reviewed International journal

    Norio Baba, Satoshi Hata, Hikaru Saito, Kenji Kaneko

    Microscopy   72 ( 2 )   111 - 134   2023.4

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  • Microstructure and Its Heat Treatment Process of Thin Films Fabricated by Alternate Sputtering of (Bi, Pb) 2 Sr 2 CaCu 2 O x and Pb–Ca–Cu–O Targets on SrTiO 3 Substrates Reviewed International journal

    33 ( 5 )   1 - 5   2023.3

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  • Interfacial Molecular Compatibility for Programming Organic–Metal Oxide Superlattices Reviewed International journal

    15 ( 22 )   27099 - 27109   2023.3

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  • A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu Invited Reviewed International journal

    Nature Astronomy   7 ( 2 )   170 - 181   2023.2

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  • A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu

    Noguchi Takaaki, Matsumoto Toru, Miyake Akira, Igami Yohei, Haruta Mitsutaka, Saito Hikaru, Hata Satoshi, Seto Yusuke, Miyahara Masaaki, Tomioka Naotaka, Ishii Hope A., Bradley John P., Ohtaki Kenta K., Dobrică Elena, Leroux Hugues, Le Guillou Corentin, Jacob Damien, de la Peña Francisco, Laforet Sylvain, Marinova Maya, Langenhorst Falko, Harries Dennis, Beck Pierre, Phan Thi H. V., Rebois Rolando, Abreu Neyda M., Gray Jennifer, Zega Thomas, Zanetta Pierre-M., Thompson Michelle S., Stroud Rhonda, Burgess Kate, Cymes Brittany A., Bridges John C., Hicks Leon, Lee Martin R., Daly Luke, Bland Phil A., Zolensky Michael E., Frank David R., Martinez James, Tsuchiyama Akira, Yasutake Masahiro, Matsuno Junya, Okumura Shota, Mitsukawa Itaru, Uesugi Kentaro, Uesugi Masayuki, Takeuchi Akihisa, Sun Mingqi, Enju Satomi, Takigawa Aki, Michikami Tatsuhiro, Nakamura Tomoki, Matsumoto Megumi, Nakauchi Yusuke, Abe Masanao, Arakawa Masahiko, Fujii Atsushi, Hayakawa Masahiko, Hirata Naru, Hirata Naoyuki, Honda Rie, Honda Chikatoshi, Hosoda Satoshi, Iijima Yu-ichi, Ikeda Hitoshi, Ishiguro Masateru, Ishihara Yoshiaki, Iwata Takahiro, Kawahara Kousuke, Kikuchi Shota, Kitazato Kohei, Matsumoto Koji, Matsuoka Moe, Mimasu Yuya, Miura Akira, Morota Tomokatsu, Nakazawa Satoru, Namiki Noriyuki, Noda Hirotomo, Noguchi Rina, Ogawa Naoko, Ogawa Kazunori, Okada Tatsuaki, Okamoto Chisato, Ono Go, Ozaki Masanobu, Saiki Takanao, Sakatani Naoya, Sawada Hirotaka, Senshu Hiroki, Shimaki Yuri, Shirai Kei, Sugita Seiji, Takei Yuto, Takeuchi Hiroshi, Tanaka Satoshi, Tatsumi Eri, Terui Fuyuto, Tsukizaki Ryudo, Wada Koji, Yamada Manabu, Yamada Tetsuya, Yamamoto Yukio, Yano Hajime, Yokota Yasuhiro, Yoshihara Keisuke, Yoshikawa Makoto, Yoshikawa Kent, Fukai Ryohta, Furuya Shizuho, Hatakeda Kentaro, Hayashi Tasuku, Hitomi Yuya, Kumagai Kazuya, Miyazaki Akiko, Nakato Aiko, Nishimura Masahiro, Soejima Hiromichi, Suzuki Ayako I., Usui Tomohiro, Yada Toru, Yamamoto Daiki, Yogata Kasumi, Yoshitake Miwa, Connolly Harold C., Lauretta Dante S., Yurimoto Hisayoshi, Nagashima Kazuhide, Kawasaki Noriyuki, Sakamoto Naoya, Okazaki Ryuji, Yabuta Hikaru, Naraoka Hiroshi, Sakamoto Kanako, Tachibana Shogo, Watanabe Sei-ichiro, Tsuda Yuichi

    Nature Astronomy   7 ( 2 )   170 - 181   2023.2   ISSN:2397-3366 eISSN:23973366

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    Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe³⁺ to Fe²⁺ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss.

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  • Microstructural factors dictating the initial plastic deformation behavior of an ultrafine-grained Fe–22Mn-0.6 C TWIP steel Reviewed International journal

    862   144506   2023.1

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  • Deep learning-based noise filtering toward millisecond order imaging by using scanning transmission electron microscopy Reviewed

    Shiro Ihara, Hikaru Saito, Mizumo Yoshinaga, Lavakumar Avala, Mitsuhiro Murayama

    Scientific Reports   12 ( 1 )   13462   2022.8   ISSN:2045-2322 eISSN:2045-2322

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    Abstract

    Application of scanning transmission electron microscopy (STEM) to in situ observation will be essential in the current and emerging data-driven materials science by taking STEM’s high affinity with various analytical options into account. As is well known, STEM’s image acquisition time needs to be further shortened to capture a targeted phenomenon in real-time as STEM’s current temporal resolution is far below the conventional TEM’s. However, rapid image acquisition in the millisecond per frame or faster generally causes image distortion, poor electron signals, and unidirectional blurring, which are obstacles for realizing video-rate STEM observation. Here we show an image correction framework integrating deep learning (DL)-based denoising and image distortion correction schemes optimized for STEM rapid image acquisition. By comparing a series of distortion corrected rapid scan images with corresponding regular scan speed images, the trained DL network is shown to remove not only the statistical noise but also the unidirectional blurring. This result demonstrates that rapid as well as high-quality image acquisition by STEM without hardware modification can be established by the DL. The DL-based noise filter could be applied to in-situ observation, such as dislocation activities under external stimuli, with high spatio-temporal resolution.

    DOI: 10.1038/s41598-022-17360-3

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  • K-doped Ba122 epitaxial thin film on MgO substrate by buffer engineering Reviewed International journal

    Dongyi Qin, Kazumasa Iida, Zimeng Guo, Chao Wang, Hikaru Saito, Satoshi Hata, Michio Naito, Akiyasu Yamamoto

    Superconductor Science and Technology   35 ( 9 )   09LT01   2022.8

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  • Deep learning-based noise filtering toward millisecond order imaging by using scanning transmission electron microscopy Reviewed International journal

    Shiro Ihara, Hikaru Saito, Mizumo Yoshinaga, Lavakumar Avala, Mitsuhiro Murayama

    Scientific reports   12 ( 1 )   13462   2022.8

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  • Immobilization of a [Co<SUP>III</SUP>Co<SUP>II</SUP>(H<sub>2</sub>O)W<sub>11</sub>O<sub>39</sub>]<SUP>7-</SUP> Polyoxoanion for the Photocatalytic Oxygen Evolution Reaction

    Nandan, SP; Gumerova, NI; Schubert, JS; Saito, H; Rompel, A; Cherevan, A; Eder, D

    ACS MATERIALS AU   2 ( 4 )   505 - 515   2022.7   ISSN:2694-2461

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    The ongoing transition to renewable energy sources and the implementation of artificial photosynthetic setups call for an efficient and stable water oxidation catalyst (WOC). Here, we heterogenize a molecular all-inorganic [CoIIICoII(H2O)W11O39]7-({CoIIICoIIW11}) Keggin-type polyoxometalate (POM) onto a model TiO2surface, employing a 3-aminopropyltriethoxysilane (APTES) linker to form a novel heterogeneous photosystem for light-driven water oxidation. The {CoIIICoIIW11}-APTES-TiO2hybrid is characterized using a set of spectroscopic and microscopic techniques to reveal the POM integrity and dispersion to elucidate the POM/APTES and APTES/TiO2binding modes as well as to visualize the attachment of individual clusters. We conduct photocatalytic studies under heterogeneous and homogeneous conditions and show that {CoIIICoIIW11}-APTES-TiO2performs as an active light-driven WOC, wherein {CoIIICoIIW11} acts as a stable co-catalyst for water oxidation. In contrast to the homogeneous WOC performance of this POM, the heterogenized photosystem yields a constant WOC rate for at least 10 h without any apparent deactivation, demonstrating that TiO2not only stabilizes the POM but also acts as a photosensitizer. Complementary studies using photoluminescence (PL) emission spectroscopy elucidate the charge transfer mechanism and enhanced WOC activity. The {CoIIICoIIW11}-APTES-TiO2photocatalyst serves as a prime example of a hybrid homogeneous-heterogeneous photosystem that combines the advantages of solid-state absorbers and well-defined molecular co-catalysts, which will be of interest to both scientific communities and applications in photoelectrocatalysis and CO2reduction.

    DOI: 10.1021/acsmaterialsau.2c00025

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  • Immobilization of a [CoᴵᴵᴵCoᴵᴵ (H₂O) W₁₁O₃₉] ⁷⁻ Polyoxoanion for the Photocatalytic Oxygen Evolution Reaction Reviewed International journal

    2 ( 4 )   505 - 515   2022.7

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  • Surface Anchoring and Active Sites of [Mo<inf>3</inf>S<inf>13</inf>]<sup>2-</sup> Clusters as Co-Catalysts for Photocatalytic Hydrogen Evolution

    Batool S., Nandan S.P., Myakala S.N., Rajagopal A., Schubert J.S., Ayala P., Naghdi S., Saito H., Bernardi J., Streb C., Cherevan A., Eder D.

    ACS Catalysis   12 ( 11 )   6641 - 6650   2022.6   ISSN:2155-5435

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    Achieving light-driven splitting of water with high efficiency remains a challenging task on the way to solar fuel exploration. In this work, to combine the advantages of heterogeneous and homogeneous photosystems, we covalently anchor noble-metal- and carbon-free thiomolybdate [Mo3S13]2-clusters onto photoactive metal oxide supports to act as molecular co-catalysts for photocatalytic water splitting. We demonstrate that strong and surface-limited binding of the [Mo3S13]2-to the oxide surfaces takes place. The attachment involves the loss of the majority of the terminal S22-groups, upon which Mo-O-Ti bonds with the hydroxylated TiO2surface are established. The heterogenized [Mo3S13]2-clusters are active and stable co-catalysts for the light-driven hydrogen evolution reaction (HER) with performance close to the level of the benchmark Pt. Optimal HER rates are achieved for 2 wt % cluster loadings, which we relate to the accessibility of the TiO2surface required for efficient hole scavenging. We further elucidate the active HER sites by applying thermal post-treatments in air and N2. Our data demonstrate the importance of the trinuclear core of the [Mo3S13]2-cluster and suggest bridging S22-and vacant coordination sites at the Mo centers as likely HER active sites. This work provides a prime example for the successful heterogenization of an inorganic molecular cluster as a co-catalyst for light-driven HER and gives the incentive to explore other thio(oxo)metalates.

    DOI: 10.1021/acscatal.2c00972

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  • Exciton-dielectric mode coupling in MoS<sub>2</sub> nanoflakes visualized by cathodoluminescence

    Vu, DT; Matthaiakakis, N; Saito, H; Sannomiya, T

    NANOPHOTONICS   11 ( 9 )   2129 - 2137   2022.5   ISSN:2192-8606 eISSN:2192-8614

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    Two-dimensional (2D) transition metal dichalcogenides (TMDCs), possessing unique exciton luminescence properties, have attracted significant attention for use in optical and electrical devices. TMDCs are also high refractive index materials that can strongly confine the electromagnetic field in nanoscale dimensions when patterned into nanostructures, thus resulting in complex light emission that includes exciton and dielectric resonances. Here, we use cathodoluminescence (CL) to experimentally visualize the emission modes of single molybdenum disulfide (MoS2) nanoflakes and to investigate luminescence enhancement due to dielectric resonances in nanoscale dimensions, by using a scanning transmission electron microscope. Specifically, we identify dielectric modes whose resonant wavelength is sensitive to the shape and size of the nanoflake, and exciton emission peaks whose energies are insensitive to the geometry of the flakes. Using a four-dimensional CL method and boundary element method simulations, we further theoretically and experimentally visualize the emission polarization and angular emission patterns, revealing the coupling of the exciton and dielectric resonant modes. Such nanoscopic observation provides a detailed understanding of the optical responses of MoS2 including modal couplings of excitons and dielectric resonances which play a crucial role in the development of energy conversion devices, single-photon emitters, and nanophotonic circuits with enhanced light-matter interactions.

    DOI: 10.1515/nanoph-2021-0643

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  • Surface Anchoring and Active Sites of [Mo3S13]2– Clusters as Co-Catalysts for Photocatalytic Hydrogen Evolution Reviewed International journal

    12 ( 11 )   6641 - 6650   2022.5

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    Other Link: https://pubs.acs.org/doi/full/10.1021/acscatal.2c00972

  • High capacity all-solid-state lithium battery enabled by in situ formation of an ionic conduction path by lithiation of MgH 2 Reviewed International journal

    Atsushi Inoishi, Hiroki Sato, Yixin Chen, Hikaru Saito, Ryo Sakamoto, Hikari Sakaebe, Shigeto Okada

    RSC advances   12 ( 17 )   10749 - 10754   2022.4

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    Other Link: https://pubs.rsc.org/en/content/articlehtml/2022/ra/d2ra01199a

  • High capacity all-solid-state lithium battery enabled by <i>in situ</i> formation of an ionic conduction path by lithiation of MgH<sub>2</sub>

    Inoishi, A; Sato, H; Chen, YX; Saito, H; Sakamoto, R; Sakaebe, H; Okada, S

    RSC ADVANCES   12 ( 17 )   10749 - 10754   2022.3   eISSN:2046-2069

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    All-solid-state Li batteries have attracted significant attention because of their high energy density and high level of safety. In a solid-state Li-ion battery, the electrodes contain a solid electrolyte that does not contribute directly to the capacity. Therefore, a battery that does not require a solid electrolyte in its electrode mixture should exhibit a higher energy density. In this study, a MgH2 electrode was used as the negative electrode material without a solid electrolyte in its mixture. The resultant battery demonstrated excellent performance because of the formation of an ionic conduction path based on LiH in the electrode mixture. LiH and Mg clearly formed upon lithiation and returned to MgH2 upon delithiation as revealed by TEM-EELS analysis. This mechanism of in situ electrolyte formation enables the development of a solid-state battery with a high energy density.

    DOI: 10.1039/d2ra01199a

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  • Water-Selective Nanostructured Dehumidifiers for Molecular Sensing Spaces

    Liu, JY; Nagashima, K; Hosomi, T; Lei, WJ; Zhang, GZ; Takahashi, T; Zhao, XX; Hanai, Y; Nakao, A; Nakatani, M; Tanaka, W; Saito, H; Kanai, M; Shimada, T; Yasui, T; Baba, Y; Yanagida, T

    ACS SENSORS   7 ( 2 )   534 - 544   2022.2   ISSN:2379-3694

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    Humidity and moisture effects, frequently called water poisoning, in surroundings are inevitable for various molecular sensing devices, strongly affecting their sensing characteristics. Here, we demonstrate a water-selective nanostructured dehumidifier composed of ZnO/TiO2/CaCl2core-shell heterostructured nanowires for molecular sensing spaces. The fabricated nanostructured dehumidifier is highly water-selective without detrimental adsorptions of various volatile organic compound molecules and can be repeatedly operated. The thermally controllable and reversible dehydration process of CaCl2·nH2O thin nanolayers on hydrophilic ZnO/TiO2nanowire surfaces plays a vital role in such water-selective and repeatable dehumidifying operations. Furthermore, the limitation of detection for sensing acetone and nonanal molecules in the presence of moisture (relative humidity ∼90%) was improved more than 20 times using nanocomposite sensors by operating the developed nanostructured dehumidifier. Thus, the proposed water-selective nanostructured dehumidifier offers a rational strategy and platform to overcome water poisoning issues for various molecular and gas sensors.

    DOI: 10.1021/acssensors.1c02378

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  • Recent Studies on TEM/STEM Tomography

    Hata Satoshi, Zhao Yifang, Ihara Shiro, Saito Hikaru, Mitsuhara Masatoshi, Murayama Mitsuhiro

    Materia Japan   61 ( 2 )   84 - 88   2022.2   ISSN:13402625 eISSN:18845843

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    DOI: 10.2320/materia.61.84

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  • Water-Selective Nanostructured Dehumidifiers for Molecular Sensing Spaces Reviewed International journal

    Jiangyang Liu, Kazuki Nagashima, Takuro Hosomi, Wenjin Lei, Guozhu Zhang, Tsunaki Takahashi, Xixi Zhao, Yosuke Hanai, Atsuo Nakao, Masaya Nakatani, Wataru Tanaka, Hikaru Saito, Masaki Kanai, Taisuke Shimada, Takao Yasui, Yoshinobu Baba, Takeshi Yanagida

    ACS sensors   7 ( 2 )   534 - 544   2022.1

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    Other Link: https://pubs.acs.org/doi/full/10.1021/acssensors.1c02378

  • Exciton-dielectric mode coupling in MoS2 nanoflakes visualized by cathodoluminescence Reviewed International journal

    Dung Thi Vu, Nikolaos Matthaiakakis, Hikaru Saito, Takumi Sannomiya

    Nanophotonics   11 ( 9 )   2129 - 2137   2022.1

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    Other Link: https://www.degruyter.com/document/doi/10.1515/nanoph-2021-0643/html?lang=en

  • Microwave synthesis of ZnO microcrystals with novel asymmetric morphology Reviewed International journal

    Wojciech Klich, Miki Inada, Hongy Gao, Hikaru Saito, Michitaka Ohtaki

    Advanced Powder Technology   32 ( 11 )   4356 - 4363   2021.11

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    Other Link: https://www.sciencedirect.com/science/article/pii/S0921883121004659

  • Approaching the ultimate superconducting properties of (Ba, K) Fe2As2 by naturally formed low-angle grain boundary networks Reviewed International journal

    Kazumasa Iida, Dongyi Qin, Chiara Tarantini, Takafumi Hatano, Chao Wang, Zimeng Guo, Hongye Gao, Hikaru Saito, Satoshi Hata, Michio Naito, Akiyasu Yamamoto

    NPG Asia Materials   13 ( 1 )   1 - 9   2021.10

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    Other Link: https://www.nature.com/articles/s41427-021-00337-5

  • Synergistic Effect of Chemical Substitution and Insertion on the Thermoelectric Performance of Cu26V2Ge6S32 Colusite Reviewed International journal

    Yuta Shimizu, Koichiro Suekuni, Hikaru Saito, Pierric Lemoine, Emmanuel Guilmeau, Bernard Raveau, Raju Chetty, Michihiro Ohta, Toshiro Takabatake, Michitaka Ohtaki

    Inorganic chemistry   60 ( 15 )   11364 - 11373   2021.7

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  • Key Role of d0 and d10 Cations for the Design of Semiconducting Colusites: Large Thermoelectric ZT in Cu26Ti2Sb6S32 Compounds Reviewed International journal

    Takashi Hagiwara, Koichiro Suekuni, Pierric Lemoine, Andrew R Supka, Raju Chetty, Emmanuel Guilmeau, Bernard Raveau, Marco Fornari, Michihiro Ohta, Rabih Al Rahal Al Orabi, Hikaru Saito, Katsuaki Hashikuni, Michitaka Ohtaki

    Chemistry of Materials   33 ( 9 )   3449 - 3456   2021.4

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    DOI: 10.1021/acs.chemmater.1c00872

  • High J(c) and low anisotropy of hydrogen doped NdFeAsO superconducting thin film Reviewed International journal

    SCIENTIFIC REPORTS   11 ( 1 )   2021.3

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    DOI: 10.1038/s41598-021-85216-3

  • The impact of surface Cu 2+ of ZnO/(Cu 1− x Zn x) O heterostructured nanowires on the adsorption and chemical transformation of carbonyl compounds Reviewed International journal

    12 ( 14 )   5073 - 5081   2021.2

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  • Realization of epitaxial thin films of the superconductor K-doped BaFe2As2 Reviewed International journal

    Dongyi Qin, Kazumasa Iida, Takafumi Hatano, Hikaru Saito, Yiming Ma, Chao Wang, Satoshi Hata, Michio Naito, Akiyasu Yamamoto

    PHYSICAL REVIEW MATERIALS   5 ( 1 )   2021.1

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    DOI: 10.1103/PhysRevMaterials.5.014801

  • Electron tomography: An imaging method for materials deformation dynamics Reviewed International journal

    S Hata, T Honda, H Saito, M Mitsuhara, TC Petersen, M Murayama

    Current Opinion in Solid State and Materials Science   24 ( 4 )   2020.8

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  • Electron tomography imaging methods with diffraction contrast for materials research Reviewed International journal

    Satoshi Hata, Hiromitsu Furukawa, Takashi Gondo, Daisuke Hirakami, Noritaka Horii, Ken-Ichi Ikeda, Katsumi Kawamoto, Kosuke Kimura, Syo Matsumura, Masatoshi Mitsuhara, Hiroya Miyazaki, Shinsuke Miyazaki, Mitsu Mitsuhiro Murayama, Hideharu Nakashima, Hikaru Saito, Masashi Sakamoto, Shigeto Yamasaki

    Microscopy   69 ( 3 )   141 - 155   2020.6

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  • Enargite Cu3PS4 A Cu–S-Based Thermoelectric Material with a Wurtzite-Derivative Structure Reviewed

    30 ( 22 )   2020.5

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    Compound semiconductors derived from ZnS (zincblende and wurtzite) with tetrahedral framework structures have functions for various applications. Examples of such materials include Cu–S-based materials with zincblende-derivative structures, which have attracted attention as thermoelectric (TE) materials over the past decade. This study illuminates superior TE performance in polycrystalline samples of enargite Cu3P1− xGexS4 with a wurtzite-derivative structure. The substitution of Ge for P dopes holes into the top of the valence band composed of Cu-3d and S-3p, whereby its multiband characteristic leads to a high TE power factor. Furthermore, a reduction in the grain size to 50–300 nm can effectively decrease phonon mean free paths, leading to low thermal conductivity. These features result in a dimensionless TE figure of merit ZT of 0.5 at 673 K for the x = 0.2 sample. Environmentally benign and low-cost characteristics of the constituent elements of Cu3PS4, as well as its high-performance thermoelectricity, make it a promising candidate for large-scale TE applications. Furthermore, this finding extends the development field of Cu–S-based TE materials to those with wurtzite-derivative structures.

    DOI: 10.1002/adfm.202000973

  • Atomic-scale phonon scatterers in thermoelectric colusites with a tetrahedral framework structure Reviewed

    Koichiro Suekuni, Yuta Shimizu, Eiji Nishibori, Hidetaka Kasai, Hikaru Saito, Daichi Yoshimoto, Katsuaki Hashikuni, Yohan Bouyrie, Raju Chetty, Michihiro Ohta, Emmanuel Guilmeau, Toshiro Takabatake, Kosuke Watanabe, Michitaka Ohtaki

    Journal of Materials Chemistry A   7 ( 1 )   228 - 235   2019.1

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    DOI: 10.1039/c8ta08248k

  • Microscopic observation of precipitation behavior at friction stirring zone of super duplex stainless steel Reviewed

    Itto Sugimoto, Seung Hwan C. Park, Satoshi Hirano, Hikaru Saito, Satoshi Hata

    Materials Transactions   60 ( 9 )   2003 - 2007   2019.1

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    DOI: 10.2320/matertrans.M2019069

  • TEM内その場変形トモグラフィー観察システムの開発 Reviewed

    波多 聰, 宮崎 裕也, 斉藤 光, 村山 光宏, 佐藤 和久, 工藤 博幸, 古河 弘光, 川本 克巳, 堀井 則孝, 加茂 勝己, 宮崎 伸介, 權堂 貴志

    54 ( 1 )   44 - 48   2019

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    We have developed a unique methodology and a new hardware/software-integrated system for in-situ straining and electron tomography (ET) experiments. The central software of the system controls a straining-and-tomography specimen holder, imaging devices and the specimen stage of a transmission electron microscope (TEM) in an integrated manner. Using the system, one can perform in-situ time-resolved three-dimensional (3D) studies that explore in real-time and at sub-microscopic levels the internal behavior of materials subjected to external stresses. 3D visualization of a Pb–Sn solder alloy thin foil's deformation dynamics by iterative step-wise stress loading and tilt-series data sets acquisition is introduced as an application of the system.

    DOI: 10.11410/kenbikyo.54.1_44

  • マテリアル系電子線トモグラフィーの実際と動向 Reviewed

    波多 聰, 斉藤 光, 村山 光宏, 佐藤 和久, 工藤 博幸

    まてりあ : 日本金属学会会報   57 ( 12 )   589 - 594   2018

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    DOI: 10.2320/materia.57.589

  • Coupling of plasmonic nanopore pairs Facing dipoles attract each other Reviewed

    Takumi Sannomiya, Hikaru Saito, Juliane Junesch, Naoki Yamamoto

    Light: Science and Applications   5 ( 9 )   2016.9

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    DOI: 10.1038/lsa.2016.146

  • Three-dimensional arrangements of perovskite-type oxide nano-fiber webs for effective soot oxidation Reviewed

    Chanmin Lee, Yukwon Jeon, Satoshi Hata, Joo Il Park, Ryutaro Akiyoshi, Hikaru Saito, Yasutake Teraoka, Yong Gun Shul, Hisahiro Einaga

    Applied Catalysis B: Environmental   191   157 - 164   2016.8

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    DOI: 10.1016/j.apcatb.2016.03.001

  • Electron microscopy analysis of microstructure of postannealed aluminum nitride template Reviewed

    Jesbains Kaur, Noriyuki Kuwano, Khairur Rijal Jamaludin, Masatoshi Mitsuhara, Hikaru Saito, Satoshi Hata, Shuhei Suzuki, Hideto Miyake, Kazumasa Hiramatsu, Hiroyuki Fukuyama

    Applied Physics Express   9 ( 6 )   2016.6

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    DOI: 10.7567/APEX.9.065502

  • Catalytic performances of perovskite oxides for CO oxidation under microwave irradiation Reviewed

    Hisahiro Einaga, Yusaku Nasu, Manabu Oda, Hikaru Saito

    Chemical Engineering Journal   283   97 - 104   2016.1

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    DOI: 10.1016/j.cej.2015.07.051

  • Formation of a hybrid plasmonic waveguide mode probed by dispersion measurement Reviewed

    H. Saito, H. Kurata

    Journal of Applied Physics   117 ( 13 )   2015.4

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    DOI: 10.1063/1.4916800

  • Codeposition of colloidal platinum particles and iron chloride precursor on TiO2 for efficient catalytic oxidation of CO to CO2 Reviewed

    Hisahiro Einaga, Ryo Shiranita, Hikaru Saito, Satoshi Hata

    Chemistry Letters   44 ( 12 )   1786 - 1788   2015

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    DOI: 10.1246/cl.150903

  • Size dependence of band structures in a two-dimensional plasmonic crystal with a square lattice Reviewed

    Naoki Yamamoto, Hikaru Saito

    Optics Express   22 ( 24 )   29761 - 29777   2014.12

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    DOI: 10.1364/OE.22.029761

  • Cathodoluminescence of 2D plasmonic crystals with hexagonal lattice

    Hikaru Saito, Naoki Yamamoto

    JSAP-OSA Joint Symposia, JSAP 2014 JSAP-OSA Joint Symposia, JSAP 2014   2014.9

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  • Direct measurement of dispersion relation for surface plasmon-polaritons on silver nanoantennas Reviewed

    Hikaru Saito, Hiroki Kurata

    Microscopy   63 ( 2 )   155 - 159   2014.1

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    DOI: 10.1093/jmicro/dft048

  • HRTEM and HAADF-STEM of precipitates at peak ageing of cast A319 aluminium alloy Reviewed

    Amporn Wiengmoon, John T.H. Pearce, Torranin Chairuangsri, Seiji Isoda, Hikaru Saito, Hiroki Kurata

    Micron   45   32 - 36   2013.2

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    DOI: 10.1016/j.micron.2012.10.009

  • Photoassisted scanning tunneling microscopy investigation on the ZnO(0001)-Zn surface treated by alkaline solution Reviewed

    Wan Hsien Lin, Hikaru Saito, Takashi Nemoto, Hiroki Kurata, Mitch M.C. Chou, Seiji Isoda, Jih Jen Wu

    Journal of Physical Chemistry C   116 ( 19 )   10664 - 10671   2012.5

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    DOI: 10.1021/jp302045j

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Professional Memberships

  • The Japanese Society of Microscopy

  • The Japan Society of Applied Physics

  • The Physical Sociaty of Japan

Committee Memberships

  • Organizer   Domestic

    2024.4 - Present   

  • Steering committee member   Domestic

    2021.4 - 2023.3   

  • 日本物理学会   領域10運営委員   Domestic

    2021.4 - 2023.3   

Research Projects

  • Developing a data-driven, real-time electron microscopy method toward interpreting plastic deformation and fracture mechanisms of structural materials in sub-microscopic level.

    Grant number:23H00238  2023.4 - 2027.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

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    Grant type:Scientific research funding

    CiNii Research

  • 励起イベント選択型カソードルミネセンス顕微鏡の開発

    Grant number:23K17350  2023 - 2025

    日本学術振興会  科学研究費助成事業  挑戦的研究(開拓)

    斉藤 光, 滝口 雅人

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    Authorship:Principal investigator  Grant type:Scientific research funding

    高速かつ省エネルギーなデバイス開発はナノフォトニクス分野における重要課題であり、ナノメートルの空間分解能を有するカソードルミネセンス(CL)はナノ材料やデバイス機能の解析の強力な手法となり得る。従来のCLは類似のフォトルミネセンス(PL)のような励起エネルギー選択性がなく、様々な励起状態を区別することなく緩和過程を計測するため、種々の現象を切り分けて解析することができない。本研究では新型CL顕微鏡を開発し、時間分解PLと定量比較可能な計測をナノメートルオーダーの空間分解能で実現するとともに、未解明であった半導体におけるCLの機構を解明する。

    CiNii Research

  • 高速電子で拓く次世代ナノ光制御領域のマネジメント

    Grant number:22H05031  2022.5 - 2025.3

    科学研究費助成事業  学術変革領域研究(B)

    三宮 工, 斉藤 光, 弓削 達郎, 秋葉 圭一郎

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    Grant type:Scientific research funding

    本領域は、物理・原理を基礎とするグループ、装置を専門とするグループ、応用をメインで実施するグループと専門の異なる研究者から形成される。その中で、原理班の知見を装置班の開発に繋げ、開発した装置を応用班の研究に展開する連携が必要となる。各計画班の代表から編成される総括班は、計画班内のメンバーを含めてタイトなコミュニケーションをとり、最新の進捗を共有しながら短・長期的な目標設定をし、他分野を含めた研究を展開するかじ取りを行う。

    CiNii Research

  • トポロジカルプラズモン導波路によるスピン選択アクティブ光制御

    Grant number:23K23196  2022.4 - 2025.3

    科学研究費助成事業  基盤研究(B)

    斉藤 光, 秋葉 圭一郎, 小袋 由貴

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    Grant type:Scientific research funding

    スピン情報を保護した量子情報通信の基盤技術として、トポロジーの概念に立脚したスピン整流性のある無散乱プラズモン導波を利用したアクティブ光制御を創出する。本研究で実現するプラズモン導波路は金属ナノ構造の周期配列から成り、個々の金属ナノ構造に励起される局在プラズモン共鳴の光アンテナ効果によって、導波路近傍に配置された物質の光吸収と発光効率が上昇する。このナノ構造中に半導体材料を組み込み、近赤外領域で光駆動する高速デバイスを作製する。作製したデバイスを走査透過電子顕微鏡-カソードルミネセンスとパルスレーザーによる時間分解分光で多角的に解析し、動作原理を明らかにしつつスピン選択相互作用を実証する。

    CiNii Research

  • トポロジカルプラズモン導波路によるスピン選択アクティブ光制御

    Grant number:22H01928  2022 - 2024

    日本学術振興会  科学研究費助成事業  基盤研究(B)

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    Authorship:Principal investigator  Grant type:Scientific research funding

  • 見えない光のナノ計測

    Grant number:22H05034  2022 - 2024

    日本学術振興会・文部科学省  科学研究費助成事業  学術変革領域研究(B)

    斉藤 光

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    Authorship:Principal investigator  Grant type:Scientific research funding

    デバイス駆動中の状態変化をナノスケールで分光イメージングできる手法が確立されれば、光-物質相互作用の増強を利用した物質機能の活用法がより理解され、電子と光子の両方の長所を上手く活用した新規デバイスの開発・開拓が進展する。本研究課題では、エネルギー分解能が飛躍的に向上した現在の電子エネルギー損失分光(EELS)に運動量分解法を適用し、未だ実現されていない電子状態と光学状態の同時解析を実現する。この新規EELS法により、光プローブでは直接アクセスできない導波路を伝播する非発光モード、さらにデバイス駆動時の物質の光学定数の変化を同時に可視化し、新たなアクティブナノ光学デバイスの創出に繋げる。

    CiNii Research

  • アキラル構造からなる光角運動量ソーターの多空間同時光計測による研究

    Grant number:21H01782  2021.4 - 2024.3

    科学研究費助成事業  基盤研究(B)

    三宮 工, 藤井 稔, 斉藤 光, 秋葉 圭一郎

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    Grant type:Scientific research funding

    光の角運動量選択は量子通信・暗号化に不可欠な要素である。本研究では、この光の角運動量を定量検出するソーターを作製し実証する。これまで角運動量選択には、対掌性をもつキラル構造が提案されてきたが左右回転パリティへの応答が同等でなく、定量性・堅牢性に欠けていた。今回、アキラルな構造を用いた光アンテナ・導波路を用いて、両パリティに同等に応答する角運動量ソーターを実現する。この計測のために、光のエネルギー・励起位置・発光位置・発光角度の全情報を同時に得られる多空間同時計測カソードルミネセンスを開発する。

    CiNii Research

  • Dynamic observation of dislocation glide by machine-learning-assisted in-situ electron microscopy

    Grant number:20K21093  2020 - 2022

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Challenging Research(Exploratory)

    Saito Hikaru

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    Authorship:Principal investigator  Grant type:Scientific research funding

    Current temporal resolution of STEM is far below that of conventional TEM. Rapid image acquisition in the millisecond per frame or faster generally causes image distortion, poor electron signals, and unidirectional blurring, which are obstacles for realizing video-rate STEM observation. In this study, we have developed a deep learning (DL)-based denoising and image distortion correction for STEM rapid image acquisition, which can remove not only the statistical noise but also the unidirectional blurring. By using this DL-based denoising method, we have achieved rapid STEM tomography visualizing 3D dislocation arrangement only within five-second acquisition of all the tilt-series images even in a 300 nm thick steel specimen. Video-rate STEM observation of thermally activated dislocation glide was also realized.

    CiNii Research

  • オンチップ型ピコ秒応答量子ドットLEDを可能とするプラズモン共振器の創製

    Grant number:17K14118  2017 - 2018

    科学研究費助成事業  若手研究(B)

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    Authorship:Principal investigator  Grant type:Scientific research funding

  • 風戸研究奨励賞/STEM-CLによるプラズモン共振器中の発光増強機構の解明

    2015

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    Grant type:Donation

  • プラズモニックメソグレーティングの異常光透過特性の解明とナノ偏光フィルターの作製

    Grant number:19K22058 

    村井 俊介, 斉藤 光, 三宮 工

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    Grant type:Scientific research funding

    周期40~60 nm程度の金属メソグレーティング構造の特異な偏光フィルター作用について研究する.代表者は光の波長領域(>100nm)でのプラズモニック構造に関する研究で顕著な業績を挙げてきた.本研究でターゲットとする,メソスケール(<100nm)の構造は光の波長スケールの構造と共存可能であり,両者の効果を併せ持つ構造が設計できるため,戦略的にこのスケールの構造の研究は重要である. 3年の研究期間でメソスケール構造に特有の光学現象を明らかにし、機能の設計ができるようにすることを目標とする。

    CiNii Research

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  • ナノ構造光学 d

    2024.12 - 2025.2   Winter quarter

  • 材料情報学特論Ⅱ i

    2024.6 - 2024.8   Summer quarter

  • 材料情報学特論Ⅱ i

    2023.6 - 2023.8   Summer quarter

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    2023.4 - 2024.3   Full year

  • 総合理工学修士演習

    2023.4 - 2024.3   Full year

  • 総合理工学修士演習

    2023.4 - 2024.3   Full year

  • ナノ構造光学 d

    2022.12 - 2023.2   Winter quarter

  • 材料情報学特論Ⅱ i

    2022.6 - 2022.8   Summer quarter

  • 総合理工学修士実験

    2022.4 - 2023.3   Full year

  • 総合理工学修士演習

    2022.4 - 2023.3   Full year

  • 材料情報学特論Ⅱ i

    2021.6 - 2021.8   Summer quarter

  • 量子プロセス理工学概論Ⅳ

    2020.10 - 2020.12   Fall quarter

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