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2. Structural Analysis on Iron-Based Superconductor Pr1111 System with Oxygen Deficiency and Flourine Substitution

Author

Kodama, Katsuaki, Ishikado, Motoyuki, Esaka, Fumitaka, Iyo, Akira, Eisaki, Hiroshi, and Shamoto, Shin-ichi

Subjects
Condensed Matter - Superconductivity
Abstract

We have performed structural analyses on iron-based superconductors, PrFeAsO$_{1-y}$ and PrFeAsO$_{1-x}$F$_x$, systematically, by means of Rietveld method on neutron powder diffraction data. The shifts of iron ion valence from +2, $\delta$, are accurately determined from the occupancies of O and O$_{1-x}$F$_x$ sites obtained by the Rietveld analysis and F-concentration obtained by secondary ion-microprobe mass spectrometry. $T_\textrm{c}$-$\delta$ curve of PrFeAsO$_{1-y}$ is different from the curve of PrFeAsO$_{1-x}$F$_x$, indicating that $\delta$ is not a principal parameter for $T_\textrm{c}$ in so-called 1111 system. Structural parameters of the FeAs layers, for example, As-Fe-As bond angle and As-height from Fe layer, are different between both systems with similar $\delta$-values. Their parent compounds are also found to have different structural parameters, possibly due to the different synthetic conditions. These results suggest that the difference of structural parameters of FeAs layer is the origin of the discrepancy of $T_\textrm{c}$-$\delta$ curves of both systems and the $T_\textrm{c}$-value in the 1111 system is sensitive to the structural parameters. It may be attribute to an energy balance of the conducting bands contributing to the superconductivity., Comment: 7 pages, 7 figures

Published
2011
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24. Depth-selective chemical state analysis of fine particles using x-ray absorption

Author

Kawai, Jun, Hayakawa, Shinjiro, Esaka, Fumitaka, Zheng, Songyan, Kitajima, Yoshinori, Maeda, Kuniko, Adachi, Hirohiko, Gohshi, Yohichi, and Furuya, Keiichi

Subjects
Extended X-ray absorption fine structure -- Usage, Fly ash -- Analysis, Chemistry
Abstract

We have developed a new chemical state analysis method for fine particle powders - depth-selective X-ray absorption fine structure spectrometry. Recording both the sample current and the X-ray fluorescence intensity concurrently with the change of incident X-ray energy made it possible to obtain surface (10-100 [Angstrom]) and bulk chemical information on powder samples. Examples are presented for prefractionated coal fly ashes in which we found chemical state differences owing to the probe depth and the coal origin. The coal fly ash contains [S.sup.2-] in the bulk and [S.sup.6+] in the 10-100 [Angstrom] surface. The ratio of [S.sup.2-]/[S.sup.6+] varies with changes in coal origin, depth from the particle surface, and particle size.

Published
1995

25. Non-destructive depth analysis of the surface oxide layer on Mg2Si crystals with XPS and XAS

Author

Esaka, Fumitaka, Nojima, Takehiro, Udono, Haruhiko, Magara, Masaaki, and Yamamoto, Hiroyuki

Abstract

Depth analysis of the surface oxide layer on a Mg2Si crystal was performed with X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). In XPS, X-rays from synchrotron radiation with the energies between 2100 and 3300 eV were used as the excitation sources for depth analysis. The Si 1s and Mg 1s XPS spectra show the formation of a thinner SiO2-X layer at outermost surface and a thicker MgO layer at lower surface on the Mg2Si. In XAS, total electron yield and partial electron yield (PEY) acquisition modes were used for the measurement of Si K-edge. The PEY spectrum was obtained by detecting electrons with a fixed kinetic energy of 5, 10, 20, 30, 40, or 50 eV. Although the PEY spectrum with electrons of 5 eV shows similar features with the total electron yield spectrum, detection of electrons with 50 eV gives an increase in the ratio of a peak at 1843.7 eV to the peak assigned to Mg2Si. The peak at 1843.7 eV can be assigned to the formation of SiO2-X on the Mg2Si. From XPS and XAS results, it is indicated that a thinner SiO2-X layer at outermost surface and a thicker MgO layer at lower surface are formed at initial oxidation of the Mg2Si.

Published
2016

35. レーザー微粒子化を利用した白金族元素分離に関する研究

Author

佐伯 盛久, Saeki, Morihisa, 江坂 文孝, Esaka, Fumitaka, 田口 富嗣, Taguchi, Tomitsugu, 大場 弘則, Oba, Hironori, 佐伯 盛久, Saeki, Morihisa, 江坂 文孝, Esaka, Fumitaka, 田口 富嗣, Taguchi, Tomitsugu, 大場 弘則, and Oba, Hironori

Abstract

レーザー微粒子化を利用した高レベル放射性廃液からの白金族元素分離法を考案し、パラジウム,ロジウム,ルテニウム及びネオジムが溶解した模擬溶液を用いて原理実証実験を行った。1.5mL模擬溶液に等量のエタノールを加え、266nm紫外レーザー(レーザー強度20mJ)を40分照射することにより、模擬溶液中のパラジウム,ロジウム,ルテニウムを選択的に微粒子化し、ネオジムと分離した。サブミクロンサイズまで成長させた白金族元素微粒子をろ過又は遠心分離により回収し、誘導結合プラズマ発光分光法により試料溶液中に残存する金属イオン濃度を分析した。その結果、ネオジムイオン濃度はレーザー照射前と変化しなかったのに対し、パラジウム,ロジウム及びルテニウムイオン濃度はそれぞれ100%, 94-99%, 65-69%減少しており、レーザー微粒子化とろ過又は遠心分離との組合せにより、白金族元素を溶液中から合金微粒子として回収できることを実証した。また、さまざまな実験パラメーターに対する白金族元素の回収率依存性を調べたところ、照射レーザー強度を調整することによりパラジウムとロジウムを相互分離できることがわかった。, We proposed separation technique of platinum-group metals (PGMs) from a solution of high-level radioactive waste by using laser-induced particle formation, and performed its proof-of-principle experiment. The simulated solution of high-level radioactive liquid wastes (HLLW) was prepared by dissolving palladium (Pd), rhodium (Rh), ruthenium (Ru) and neodymium (Nd) into distilled water. The Nd metal was added as representative of lanthanide and minor actinide. After 40-min irradiation of a mixture of the simulated solution of HLLW and ethanol (v/v = 1/1) with a UV laser (266 nm, 20 mJ), the Pd, Rh and Ru metals were separated from the Nd ion as particle with sub-micron size. The PGM particles were recovered by filtration and centrifugation. Analysis of ion concentration in the sample solution by ICP-AES suggested that the Pd, Rh and Ru metals were recovered with efficiency of 100%, 94-99%, 65-69%, while the Nd ion was completely kept in the sample solution., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2012-030

Published
2012

38. Non-destructive depth analysis of the surface oxide layer on Mg2Si with XPS and XAS.

Author

Esaka, Fumitaka, Nojima, Takehiro, Udono, Haruhiko, Magara, Masaaki, and Yamamoto, Hiroyuki

Subjects
*ELECTRONIC excitation, *EXCITED state energies, *SPUTTER etching, *X-ray absorption, *SILICIDES
Abstract

Depth analysis of the surface oxide layer on a Mg2Si crystal was performed with X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). In XPS, X-rays from synchrotron radiation with the energies between 2100 and 3300 eV were used as the excitation sources for depth analysis. The Si 1s and Mg 1s XPS spectra show the formation of a thinner SiO2-X layer at outermost surface and a thicker MgO layer at lower surface on the Mg2Si. In XAS, total electron yield and partial electron yield (PEY) acquisition modes were used for the measurement of Si K-edge. The PEY spectrum was obtained by detecting electrons with a fixed kinetic energy of 5, 10, 20, 30, 40, or 50 eV. Although the PEY spectrum with electrons of 5 eV shows similar features with the total electron yield spectrum, detection of electrons with 50 eV gives an increase in the ratio of a peak at 1843.7 eV to the peak assigned to Mg2Si. The peak at 1843.7 eV can be assigned to the formation of SiO2-X on the Mg2Si. From XPS and XAS results, it is indicated that a thinner SiO2-X layer at outermost surface and a thicker MgO layer at lower surface are formed at initial oxidation of the Mg2Si. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2016
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45. Carrier doping into boron nanobelts by neutron transmutation

Author

Kirihara, Kazuhiro, primary, Shimizu, Yoshiki, additional, Yamada, Yoichi, additional, Esaka, Fumitaka, additional, Sasaki, Takeshi, additional, Koshizaki, Naoto, additional, Yamamoto, Hiroyuki, additional, Shamoto, Shin-ichi, additional, and Kimura, Kaoru, additional

Published
2010
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46. Degradation of Superconductivity and Spin Fluctuations by Electron Overdoping in LaFeAsO1-xFx

Author

Wakimoto, Shuichi, primary, Kodama, Katsuaki, additional, Ishikado, Motoyuki, additional, Matsuda, Masaaki, additional, Kajimoto, Ryoichi, additional, Arai, Masatoshi, additional, Kakurai, Kazuhisa, additional, Esaka, Fumitaka, additional, Iyo, Akira, additional, Kito, Hijiri, additional, Eisaki, Hiroshi, additional, and Shamoto, Shin-ichi, additional

Published
2010
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47. QA/QC Activities and Estimation of Uncertainty for Ultra-trace Analysis of Uranium and Plutonium in Safeguards Environmental Samples

Author

Usuda, Shigekazu, primary, Magara, Masaaki, additional, Esaka, Fumitaka, additional, Yasuda, Kenichiro, additional, Saito-Kokubu, Yoko, additional, Lee, Chi-Gyu, additional, Miyamoto, Yutaka, additional, Suzuki, Daisuke, additional, Inagawa, Jun, additional, Sakurai, Satoshi, additional, and Murata, Fujio, additional

Published
2010
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