研究者詳細 - 藤井　達生

論文 - 藤井　達生

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Preparation and Microstructure of Bluish Glass 査読

S. Murase, A. Kaminaga, H. Uenishi, R. Maki, T. Fujii, M. Takano, Y. Kusano

Proceedings of 2024 Powder Metallurgy World Congress & Exhibition 1654 - 1657 2024年12月

Synthesis of Tubular Iron Oxide Pigments with Bright Red Color Deposited on Phosphorylated Cellulose Nanofibers 査読

K. Suga, Y. Oshima, T. Okihara, T. Fujii

Proceedings of 2024 Powder Metallurgy World Congress & Exhibition 889 - 892 2024年12月

Preparation of Lepidocrocite and Maghemite by the Addition of Calcite to Iron(II) Chloride Solutions 査読

N. Arinobu, R. Maki, T. Ogawa, T. Fujii, Y. Kusano

Proceedings of 2024 Powder Metallurgy World Congress & Exhibition 1570 - 1573 2024年12月

Synthesis of Carbon Nanowalls using Plasma-Irradiated Solid Carbon and Absorption of Cs in Water 査読

Yukimasa Fukada, Yumito Aoyagi, Misaki Yokoyama, Yoichi Horibe, Jun Kano, Miyu Kaneda, Tatsuo Fujii, Akitaka Yoshigoe, Masaaki Kobata, Tatsuo Fukuda, Kenji Yoshii, Naoshi Ikeda

Journal of Electronic Materials 54 ( 1 ) 686 - 692 2024年11月

鉄複電荷酸化物RFe2O4が示す電子強誘電性の研究査読

沖本洋一, 藤井達生, 池田直

日本結晶学会誌 66 ( 2 ) 103 - 108 2024年6月

Influence of viscosity and composition of alkali borosilicate lead-free frit on its reaction with hematite, and the color control of red overglaze enamels 査読

Misa Ogawa, Yuuka Kokubo, Yuto Okawara, Hirofumi Inada, Taigo Takaishi, Tatsuo Fujii, Toshinori Okura, Hideki Hashimoto

Journal of the European Ceramic Society 43 ( 15 ) 7205 - 7214 2023年12月

c軸成長した針状六方晶フェライト粒子の合成への試み査読

西岡栞平, 山本悠, 高橋勝國, 狩野旬, 藤井達生

粉体および粉末冶金 70 ( 9 ) 398 - 401 2023年9月

Co-substituted Ca–La magnetoplumbite ferrite microwave absorbers at 100 GHz 査読

Kazushige Hyodo, Jun Kano, Makoto Nakanishi, Tatsuo Fujii

Applied Physics Letters 122 ( 11 ) 2023年3月

掲載種別：研究論文（学術雑誌）出版者・発行元：AIP Publishing

Millimeter wave absorption exceeding 70 GHz has been performed in a Co-substituted Ca–La magnetoplumbite (M-type) ferrite. A polymerized complex method was used to increase the substitution of La and Co ions in the M-type ferrite. The increase in the magnetic anisotropy field combined with the remaining significant saturation magnetization results in good magnetic resonance absorption in the millimeter range of 70–100 GHz. Above 70 GHz, good millimeter wave absorption of more than −20 dB was achieved in 0.25 mm thickness plates of Ca0.46La0.54Fe11Co0.28O19-η and Ca0.42La0.58Fe11Co0.58O19-η. Highly Co-substituted Ca–La M-type ferrites may, thus, be promising candidates for magnetic absorption materials operating in frequencies of up to 100 GHz.

DOI： 10.1063/5.0133578

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Nonlinear Optical Properties in an Epitaxial YbFe2O4 Film Probed by Second Harmonic and Terahertz Generation 査読

Hongwu Yu, Yoichi Okimoto, Atsuya Morita, Shuhei Shimanuki, Kou Takubo, Tadahiko Ishikawa, Shin-ya Koshihara, Ryusei Minakami, Hirotake Itoh, Shinichiro Iwai, Naoshi Ikeda, Takumi Sakagami, Mayu Nozaki, Tatsuo Fujii

Materials 16 ( 5 ) 1989 - 1989 2023年2月

掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG

An epitaxial film of YbFe2O4, a candidate for oxide electronic ferroelectrics, was fabricated on yttrium-stabilized zirconia (YSZ) substrate by magnetron sputtering technique. For the film, second harmonic generation (SHG), and a terahertz radiation signal were observed at room temperature, confirming a polar structure of the film. The azimuth angle dependence of SHG shows four leaves-like profiles and is almost identical to that in a bulk single crystal. Based on tensor analyses of the SHG profiles, we could reveal the polarization structure and the relationship between the film structure of YbFe2O4 and the crystal axes of the YSZ substrate. The observed terahertz pulse showed anisotropic polarization dependence consistent with the SHG measurement, and the intensity of the emitted terahertz pulse reached about 9.2% of that emitted from ZnTe, a typical nonlinear crystal, implying that YbFe2O4 can be applied as a terahertz wave generator in which the direction of the electric field can be easily switched.

DOI： 10.3390/ma16051989

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Uniform Formation of a Characteristic Nanocomposite Structure of Biogenous Iron Oxide for High Rate Performance as the Anode of Lithium-Ion Batteries 査読

Masakuni Takahashi, Ryo Sakuma, Hideki Hashimoto, Tatsuo Fujii, Jun Takada

JOURNAL OF PHYSICAL CHEMISTRY C 2223 - 2230 2023年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Recently, Fe2O3 has been considered as an alternative anode material for lithium-ion batteries (LIBs) owing to its high theoretical capacity (approximately 1000 mA h g-1), low cost, and nontoxicity. However, its rate performance remains poor relative to that of the conventional graphite anode. In this study, Fe2O3-based anodes were prepared through the annealing of biogenous Fe2O3 (L-BIOX) samples produced by an aquatic Fe-oxidizing bacterium. The effect of the annealing temperature on the performance of the synthesized Fe2O3-based material as the anode of an LIB was investigated. Electrochemical measurements revealed that the annealed L-BIOX samples at 300-700 degrees C exhibited higher rate performances than the unannealed material. Particularly, the sample annealed at 700 degrees C exhibited the highest capacity among the synthesized materials and showed a higher performance than the previously reported Fe2O3-based anodes. It exhibited a capacity of 923 mA h g-1 even at a high current density of 2 A g-1. After annealing at 700 degrees C and discharging, the synthesized biogenous material had a uniform nanocomposite structure composed of alpha-Fe2O3 nanoparticles dispersed in an amorphous matrix of Li-Si-P oxide. To form this uniform nanostructure, the solid-state diffusion resistance of the Li+ ions in the active material was reduced, which consequently improved the rate performance of the electrode. Therefore, this study provides substantial insights into the development and improvement of the performance of novel Fe2O3-based nanomaterials as the anode of LIBs.

DOI： 10.1021/acs.jpcc.2c08380

Web of Science

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Spinodal Decomposition in the Mg–Al–Fe–O System 査読

Yoshihiro Kusano, Taiki Furuta, Ryosuke Maki, Tomoyuki Ogawa, Tatsuo Fujii

Inorganic Chemistry 61 ( 45 ) 18170 - 18180 2022年11月

Eco-Benign Orange-Hued Pigment Derived from Aluminum-Enriched Biogenous Iron Oxide Sheaths. 査読国際誌

Katsunori Tamura, Yuri Oshima, Yuta Fuse, Noriyuki Nagaoka, Tatsuki Kunoh, Makoto Nakanishi, Tatsuo Fujii, Tokuro Nanba, Jun Takada

ACS omega 7 ( 15 ) 12795 - 12802 2022年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

Inorganic pigments have been widely used due to their low cost of production, strong hiding power, and chemical resistance; nevertheless, they have limited hue width and chromaticity. To eliminate these disadvantages, we herein propose the use of an ingenious biotemplate technique to produce Al-enriched biogenic iron oxide (BIOX) materials. Spectrophotometric color analysis showed that high levels of Al inclusion on heat-treated BIOX samples produced heightened yellowish hues and lightness. The Al-enriched BIOX sheaths exhibited a stable tubular structure and excellent thermal stability of color tones after heating at high temperatures and repetitive heat treatments. Ultrastructural analysis and mechanical destruction experiments revealed that the highly chromatic orange-hue of these pigments are ascribed probably to an ingenious cylindrical nanocomposite architecture composed of putative Fe-included low crystalline Al oxide regions and hematite particles embedded therein. The present work therefore demonstrates that the bioengineered material can serve as an epochal orange-hued inorganic pigment with low toxicity and marked thermostability that should meet large industrial demand.

DOI： 10.1021/acsomega.1c07390

PubMed

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Valence control of charge and orbital frustrated system YbFe<inf>2</inf>O<inf>4</inf> with electrochemical Li⁺ intercalation 査読

S. Murase, Y. Yoshikawa, K. Fujiwara, Y. Fukada, T. Teranishi, J. Kano, T. Fujii, Y. Inada, M. Katayama, K. Yoshii, T. Tsuji, D. Matsumura, N. Ikeda

Journal of Physics and Chemistry of Solids 162 110468 2022年3月

掲載種別：研究論文（学術雑誌）

We report an attempt valence control of the mixed valence iron triangular oxide YbFe2O4 to develop an effective technique controling the frustration of charges in strongly correlated electron systems. The electrochemical doping of Li + into YbFe2O4 was examined on a cell-type sample similar to the Li-ion secondary battery cell. Systematic changes in the lattice constant and Fe – Fe and Fe–Yb distance were observed with Li doping. Maximum value of the doping was over 300 mAh/g. An EXAFS experiment indicated that Li positioned between Yb octahedron layer (U-layer) and Fe-bipyramidal layer (W-layer). However, detailed change of iron valence state of YbFe2O4was not clearly observed because of the superimpose of the signal from iron metal nano particles in XANES observation. We discuss that the uncertainty might arise from the inhomogeneous distribution of the sample particle size, which might prevent the homogeneous doping of Li because the doping occurs on the surface of each nano-particles.

DOI： 10.1016/j.jpcs.2021.110468

Scopus

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High valence states of Pd supported on ferroelectric BaTiO3 driven by electric polarization

Tasuku Yoshida, Jun Kano, Masaichiro Mizumaki, Yusuke Tamenori, Kiyofumi Nitta, Kazuo Kato, Satoshi Hinokuma, Norihiro Oshime, Satoshi Hirose, Hitoshi Mikami, Naoshi Ikeda, Tatsuo Fujii, Yuta Nishina, Tomoko Okubo

Applied Physics Letters 119 ( 9 ) 092904 - 092904 2021年8月

Single domain growth and charge ordering of epitaxial YbFe2O4 films

Takumi Sakagami, Reika Ota, Jun Kano, Naoshi Ikeda, Tatsuo Fujii

CRYSTENGCOMM 2021年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

YbFe<INF>2</INF>O<INF>4</INF> is a charge-ordered ferroelectric that exhibits coupling between magnetization and electric polarization near room temperature and crystallizes in a rhombohedral structure (R3m). This study presents an attempt to fabricate stoichiometric and epitaxial YbFe<INF>2</INF>O<INF>4-delta</INF> films with a nearly single-domain structure using an RF magnetron sputtering method. The (0001)-oriented epitaxial films of YbFe<INF>2</INF>O<INF>4-delta</INF> on YSZ (111) substrates via reactive sputtering method exhibited clear three-fold symmetry normal to the substrate without the formation of twin domains rotated by 60 degrees. The oxygen stoichiometry of the epitaxial YbFe<INF>2</INF>O<INF>4-delta</INF> was improved by controlling an oxygen partial pressure (P<INF>O<INF>2</INF></INF>) during the deposition. The films showed a sharp ferrimagnetic transition, and the transition temperature (T<INF>N</INF>) increased linearly to approximately 245 K with decreasing P<INF>O<INF>2</INF></INF>. The magnitude of magnetization of the obtained films was comparable to that of bulk single crystals. Further, the electron diffraction pattern of the stoichiometric films confirmed the presence of three-dimensional charge order, which is consistent with the behavior of the bulk crystals as well.

DOI： 10.1039/d1ce00834j

Web of Science

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Light reflectance and photoelectron yield spectroscopy enable acceptor level measurement in p-type Ba1-xTiO3 semiconductor

Saya Fujii, Jun Kano, Norihiro Oshime, Tohru Higuchi, Yuta Nishina, Tatsuo Fujii, Naoshi Ikeda, Hiromi Ota

JOURNAL OF APPLIED PHYSICS 129 ( 8 ) 2021年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER INST PHYSICS

We report the band structure of Ba-deficient BaTiO3 as a p-type semiconductor, studied by a combination of light reflectance and photoelectron yield spectroscopy. Two acceptor levels were observed at the tail of a valence band. As the quantity of Ba vacancies increased, the density of state of the two acceptor levels also increased. The levels of the conduction band minimum and the valence band maximum shifted far away from the vacuum level, but the bandgap seems to be independent of Ba deficient concentration. For classical semiconductors such as Si and GaAs, the observation of impurity levels is restricted to low temperatures (similar to 20K) owing to their narrow bandgaps. Oxide semiconductors have now been demonstrated with wide bandgaps and acceptor levels, at normal operating temperatures, which could lead to new device designs in the future.

DOI： 10.1063/5.0033761

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Chemical reaction between lead-free multicomponent alkali borosilicate glass frit and hematite during heat treatment

Hideki Hashimoto, Akane Terasawa, Hirofumi Inada, Taigo Takaishi, Tatsuo Fujii, Hidetaka Asoh

JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 41 ( 1 ) 823 - 830 2021年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCI LTD

A mixture of a lead-free multicomponent alkali borosilicate glass frit containing zinc ions and hematite was heat-treated under various conditions to elucidate the reaction between the two components, which is essentially important for controlling the color of red overglaze enamels. Above the glass transition temperature, the interaction between the frit fluid and hematite was evident, as the viscosity of the frit decreased. Moreover, hematite dissolved, the iron ions diffused into the glass matrix and they precipitated on residual hematite, resulting in enhanced crystal growth through Ostwald ripening. Concurrently, the iron and zinc ions reacted to form zinc ferrite. During cooling, the supersaturated iron ions were consumed for precipitation of hematite and zinc ferrite. Because frit and hematite dramatically react during heat treatment, conventional modification of hematite alone is insufficient. Development of the frit exhibiting low reactivity toward hematite through precise control of physical properties is a future challenging issue.

DOI： 10.1016/j.jeurceramsoc.2020.08.037

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Skewed electronic band structure induced by electric polarization in ferroelectric BaTiO3

Norihiro Oshime, Jun Kano, Eiji Ikenaga, Shintaro Yasui, Yosuke Hamasaki, Sou Yasuhara, Satoshi Hinokuma, Naoshi Ikeda, Pierre-Eymeric Janolin, Jean-Michel Kiat, Mitsuru Itoh, Takayoshi Yokoya, Tatsuo Fujii, Akira Yasui, Hitoshi Osawa

SCIENTIFIC REPORTS 10 ( 1 ) 2020年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE RESEARCH

Skewed band structures have been empirically described in ferroelectric materials to explain the functioning of recently developed ferroelectric tunneling junction (FTJs). Nonvolatile ferroelectric random access memory (FeRAM) and the artificial neural network device based on the FTJ system are rapidly developing. However, because the actual ferroelectric band structure has not been elucidated, precise designing of devices has to be advanced through appropriate heuristics. Here, we perform angle-resolved hard X-ray photoemission spectroscopy of ferroelectric BaTiO3 thin films for the direct observation of ferroelectric band skewing structure as the depth profiles of atomic orbitals. The depth-resolved electronic band structure consists of three depth regions: a potential slope along the electric polarization in the core, the surface and interface exhibiting slight changes. We also demonstrate that the direction of the energy shift is controlled by the polarization reversal. In the ferroelectric skewed band structure, we found that the difference in energy shifts of the atomic orbitals is correlated with the atomic configuration of the soft phonon mode reflecting the Born effective charges. These findings lead to a better understanding of the origin of electric polarization.

DOI： 10.1038/s41598-020-67651-w

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Bright Yellowish-Red Pigment Based on Hematite/Alumina Composites with a Unique Porous Disk-like Structure

Hideki Hashimoto, Jun Kiyohara, Arisa Isozaki, Yuya Arakawa, Tatsuo Fujii, Jun Takada, Hirofumi Inada, Taigo Takaishi, Hidetaka Asoh

ACS OMEGA 5 ( 8 ) 4330 - 4337 2020年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Inspired by a bacteriogenic, iron-based oxide material and a traditional Japanese red pigment, a bright yellowish-red pigment was prepared by heating an Al-containing iron oxyhydroxide precursor. The obtained red pigment had a unique porous disk-like structure, comprising Al-substituted hematite particles and crystalline alumina nanoparticles. Although these disk-like structures loosely gathered to form an aggregate in powder, they can be easily dispersed into a single, disk-like structure by simple ultrasonic irradiation. The powder exhibited a bright yellowish-red color and high thermostability, making it attractive as a coloring material for various industrial products needing a bright-red color, high weather resistance, and durability. Quantitative color measurements revealed extremely high L*, a*, and b* values that are much greater than those of commercially available hematite. The thermostability test showed that even after exposure to high temperatures, the pigment retained the red color, indicating its high thermostability. The unique microstructure should be strongly related to the bright yellowish-red color and the high thermostability of the developed red pigment.

DOI： 10.1021/acsomega.9b04297

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Intermittent parathyroid hormone 1–34 induces oxidation and deterioration of mineral and collagen quality in newly formed mandibular bone 査読

Yohsuke Yoshioka, Eiki Yamachika, Makoto Nakanishi, Tadashi Ninomiya, Sho Akashi, Sei Kondo, Norifumi Moritani, Yasuhiro Kobayashi, Tatsuo Fujii, Seiji Iida

Scientific Reports 9 ( 1 ) 8041 2019年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

Intermittent parathyroid hormone (PTH) administration is known to promote bone healing after surgical procedures. However, the mechanism and influence of PTH on the mineral and collagen quality of the jaw are not well understood. Most studies have focused on analyzing the bone density and microstructure of the mandible, and have insufficiently investigated its mineral and collagen quality. Oxidative stress activates osteoclasts, produces advanced glycation end products, and worsens mineral and collagen quality. We hypothesized that PTH induces oxidation and affects the mineral and collagen quality of newly formed mandibular bone. To test this, we examined the mineral and collagen quality of newly formed mandibular bone in rats administered PTH, and analyzed serum after intermittent PTH administration to examine the degree of oxidation. PTH administration reduced mineralization and worsened mineral and collagen quality in newly formed bone. In addition, total anti-oxidant capacity in serum was significantly decreased and the oxidative-INDEX was increased among PTH-treated compared to vehicle-treated rats, indicating serum oxidation. In conclusion, intermittent administration of PTH reduced mineral and collagen quality in newly formed mandibular bone. This effect may have been induced by oxidation.

DOI： 10.1038/s41598-019-44389-8

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その他リンク： http://www.nature.com/articles/s41598-019-44389-8

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