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勅使河原 誠; 池田 裕二郎*; Yan, M.*; 村松 一生*; 須谷 康一*; 福住 正文*; 能田 洋平*; 小泉 智*; 猿田 晃一; 大竹 淑恵*
Nanomaterials (Internet), 13(1), p.76_1 - 76_9, 2023/01
被引用回数:2 パーセンタイル:54.89(Chemistry, Multidisciplinary)冷中性子以下の中性子強度を高めるため、ナノサイズグラフェンの集合体が、ナノダイヤモンドと同様に中性子のコヒーレント散乱を促進できることを提案した。さらには、グラフェンの強いsp2結合は、高い耐放射線性を有する可能性を秘める。理研の加速器駆動型小型中性子源やJ-PARCのiMATERIAを用いて、ナノサイズグラフェンの中性子全断面積測定,中性子小角散乱測定を行った。測定結果より、ナノサイズのグラフェン集合体は、コヒーレント散乱に起因すると考えられる冷中性子エネルギー領域での全断面積と小角散乱を増大させ、ナノダイヤモンドと同様に高い中性子強度をもたらすことを世界で初めて明らかにした。
窪田 崇秀*; 嶋田 雄介*; 土屋 朋生*; 吉川 智己*; 伊藤 啓太*; 竹田 幸治; 斎藤 祐児; 今野 豊彦*; 木村 昭夫*; 高梨 弘毅*
Nanomaterials (Internet), 11(7), p.1723_1 - 1723_11, 2021/07
被引用回数:2 パーセンタイル:17.84(Chemistry, Multidisciplinary)Heusler alloys exhibit various magnetic properties. In this study, a layered sample consisting of a Heusler alloy, MnVAl and a ferromagnet, Fe, is selected as a material system exhibiting exchange bias. Although the fully ordered MnVAl is known as a ferrimagnet, the MnVAl/Fe layered structure exhibits exchange bias. The high-angle annular dark field STEM images demonstrated the formation of MnVAl clusters with the L2 phase distributed only around the interface to the Fe layer in the sample. Furthermore, the antiferromagnetic coupling between the Mn- and Fe-moments were observed in element specific hysteresis loops measured using XMCD. The locally ordered L2 phase and antiferromagnetic Mn-moments in the MnVAl layer are important for the exchange bias.
朝岡 秀人
Proceedings of 2019 IEEE 9th International Conference on Nanomaterials: Applications & Properties (NAP 2019) (Internet), p.01SSI01_1 - 01SSI01_4, 2019/09
Nano-structure formation influences strongly the surface stress. Silicon surface produces a unique stress that corresponds to the reconstruction based on dangling bond reduction and adatom formation. We focused on surface stress measurements during reconstruction, hydrogen-termination, and bismuth-termination on Si(111) surfaces. In order to obtain information on the surface stress and the surface structure simultaneously, we combined surface-curvature and reflection high-energy electron-diffraction instrumentations in an identical ultrahigh vacuum system. The surface stress behaviors during desorption and adsorption processes on the Si(111) surfaces revealed that surface stress evolution during the surface structure formation.
草野 翔吾*; 松村 大樹; 石井 賢司*; 田中 裕久*; 水木 純一郎*
Nanomaterials (Internet), 9(4), p.642_1 - 642_14, 2019/04
被引用回数:7 パーセンタイル:37.59(Chemistry, Multidisciplinary)The oxygen reduction reaction (ORR) on Pt/C in alkaline solution was studied by in situ high energy resolution X-ray absorption spectroscopy. To discuss the X-ray absorption near-edge structure (XANES), this paper introduced the rate of change of the (RCD), which is an analysis method that is sensitive to surface adsorption. The surface adsorptions as hydrogen (below 0.34 V), superoxide anion (from 0.34 V to 0.74 V), hydroxyl species (from 0.44 V to 0.74 V), atomic oxygen (above 0.74 V), and -PtO (above 0.94 V) were distinguished. It is clarified that the catalytic activity in an alkaline solution is enhanced by the stability of atomic oxygen and the low stability of superoxide anion/peroxide adsorption on the platinum surface.
岸 浩史*; 坂本 友和*; 朝澤 浩一郎*; 山口 進*; 加藤 豪士*; Zulevi, B.*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; 松村 大樹; et al.
Nanomaterials (Internet), 8(12), p.965_1 - 965_13, 2018/12
被引用回数:11 パーセンタイル:49.2(Chemistry, Multidisciplinary)Platinum group metal-free catalysts based on transition metal-nitrogen-carbon nanomaterials have been studied by a combination of in situ X-ray spectroscopy techniques, high-resolution transmission electron microscope, Mssbauer spectroscopy, electrochemical methods and density functional theory. Fe-N-C oxygen reduction reaction electrocatalysts were synthesized by varying several synthetic parameters to obtain nanomaterials with different composition and morphology. Associated with Fe-N motive and the presence of Fe metallic particles in the electrocatalysts showed the clear differences in the variation of composition; processing and treatment conditions of sacrificial support method. From the results of material characterization; catalytic activity and theoretical studies; Fe metallic particles (coated with carbon) are main contributors into the HO generation.