研究者詳細 - 藤井　達生

論文 - 藤井　達生

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290MeV/n ⁴⁰Ar照射によるBi‐2223焼結体へのピニングセンター導入の試み

菊池丈幸, 中西真, 長江正寛, 草野圭弘, 藤井達生, 高田潤, 安田仲宏, 村上健

粉体および粉末冶金 46 ( 9 ) 994 - 998 1999年9月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人粉体粉末冶金協会

Bi-2223 bulk superconductors were irradiated with 290MeV/n40Ar18+ions.40Ar18+irradiation effects on flux pinning of Bi-2223, which were estimated as ΔM from magnetic hysteresis loops measured by SQUID and VSM, were discussed. Irradiated samples had enlarged magnetic hysteresis loops than unirradiated samples. Moreover, the increment of ΔM depended on depth from the irradiation surface. Microstructure of irradiated samples were observed by high-resolution transmission electron microscopy (HR-TEM). However, irradiation defects such as the columnar defects were not observed in these samples.

DOI： 10.2497/jjspm.46.994

In situXPS analysis of various iron oxide films grown byNO2-assisted molecular-beam epitaxy

T. Fujii, F. M. F. de Groot, G. A. Sawatzky, F. C. Voogt, T. Hibma, K. Okada

Physical Review B 59 ( 4 ) 3195 - 3202 1999年1月

Preparation and properties of a novel electromagnetic wave absorber ferrite/SiC sintered composite 査読

T. Jun, M. Nakanishi, M.Yoshino, T. Fujii, Tatsuo, M. Fukuhara, A. Doi, Y. Kusano

Adv. Powder Metall. Part. Mater. 3 11 - 19 1999年

MBE-growth of iron and iron oxide thin films on MgO(100), using NO<inf>2</inf>, NO, and N<inf>2</inf>O as oxidizing agents

F. C. Voogt, T. Hibma, P. J.M. Smulders, L. Niesen, T. Fujii

Materials Research Society Symposium - Proceedings 477 211 - 216 1997年

掲載種別：研究論文（国際会議プロシーディングス）

We have made a study of the use of NO as the source of oxygen in the MBE-growth of iron oxides thin films. It is found that NO is a much more efficient oxidizing agent than molecular O . As indicated by Moessbauer spectroscopy, performed on Fe probe layers, NO is not only capable of forming stoichiometric magnetite Fe O , but also all non-stoichiometric Fe O phases. Even the metastable maghemite phase γ-Fe O (Fe O with δ = 1/3) can be formed. All iron oxides grow layer-by-layer-like, as indicated by strong RHEED intensity oscillations. When small doses of NO are used, new wustite Fe O and Fe O phases are formed. In contrast to the Fe O films, these phases have nitrogen incorporated into the crystal lattice. Similar compounds are obtained when NO is used as the source of oxygen. The use of N O does not lead to the formation of iron oxides. It does, however, alter the growth mode of Fe on MgO(100). Whereas Fe deposited under UHV conditions forms 3D islands, the N O acts as a surfactant and induces 2D layer-by-layer growth. 2 2 2 2 3 4 3-δ 4 2 3 3-δ 4 2 1-x 3 4 3-δ 4 2 2 57

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Raman Spectra and Constitution of Binary Tellurite Glasses Containing Typical Network Modifying Cations

Akiyoshi Osaka, Qiu Jianrong, Tatsuo Fujii, Tokuro Nanba, Jun Takada, Yoshinari Miura

Journal of the Society of Materials Science, Japan 42 ( 476 ) 473 - 477 1993年

掲載種別：研究論文（学術雑誌）

The 720 and 780 cm components of the deconvoluted Raman spectra of glasses in the systems R O-TeO (R=Li, Na, K, Ba, Zn) were attributed to TeO groups and the 665 cm band was to TeO groups. The theoretical values of the molar ratio TeO /TeO derived from an assumed vitrification reaction were compared with the ratio derived from the intensity ratios of the Raman bands, I(720) /I(665) and I(780)/I(665). It was indicated that [O Te=O] and [O Te(=O)-O] units were induced by the addition of network modifying oxides in the composition range of lower atomic ratio O/Te. It was proposed that the decrease in the rate of increase of the ratio TeO /TeO in the range of larger O/Te was due to the equilibrium TeO ↔[O12/2Te=O] favoring the former unit. © 1993, The Society of Materials Science, Japan. All rights reserved. -1 -1 - n 2 3 4 3 4 2/2 1/2 3 4 4/2

DOI： 10.2472/jsms.42.473

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Microstructure of Co Ferrite Films and Co Ferrite/zn Ferrite Double Layered Films Prepared by Plasma Enhanced MOCVD

Eiji Fujii, Hideo Torii, Masumi Hattori, Tatsuo Fujii, Kiyoshi Kuribayashi, Miyoshi Inoue

Journal of the Japan Society of Powder and Powder Metallurgy 40 ( 6 ) 618 - 622 1993年

掲載種別：研究論文（学術雑誌）

Co Fe O (0. 1≤×≤1.0) films and a Co Fe O /Zn Fe O double layered film were prepared on soda-lime glass substrate (a=87×10 /deg) by plasma enhanced MOCVD and their microstructures and magnetic properties were studied. The Co ferrite films consisted of a random orientated initial layer (thickness < 100 nm) and an <100> orientated columnar layer. Conversion electron Mossbauer spectra and magnetization curves of the films indicated that the films had an easy axis perpendicular to the film plane. The Co ferrite film with higly perpendicular magnetic anisotropy could be obtained by using Zn ferrite film (thickness:210 nm) as a buffer layer between the Co ferrite film and the substrate. © 1993, Japan Society of Powder and Powder Metallurgy. All rights reserved. x a-x 4 0.1 2.9 4 0.5 2.5 4 -7

DOI： 10.2497/jjspm.40.618

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Microstructure of Hydroxyapatite-Hematite Composite Particles Prepared by Ultrasonic Spray Pyrolysis

Osaka Akiyoshi, Chiba Akira, Fujii Tatsuo, Nanba Tokuro, Takada Jun, Miura Yoshinari

Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy 39 ( 3 ) 239 - 242 1992年

掲載種別：研究論文（学術雑誌）

Aqueous solutions of calcium nitrate stabilized with EDTA, ammonium dihydrogen orthophosphate and iron (III) nitrate were mixed before they were subject to ultrasonic spraying and to subsequent pyrolysis in an electric furnace, and particles of 0.45μm in average diameter consisting of hydroxyapatite and hematite were obtained. Surface morphology and microstructure of the particles were examined. A nucleus (hematite)-shell (hydroxyapatite) type structure was observed for larger particles (>0.8μm in diameter) though the particles of medium size apparently had a uniform microstructure. Such structural difference due to the particle size was explained in terms of decomposition of the Ca-EDTA chelating bond at lowest temperatures and temperature distribution in the sprayed mists. © 1992, Japan Society of Powder and Powder Metallurgy. All rights reserved.

DOI： 10.2497/jjspm.39.239

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Cryogenic resonance-electron Mössbauer spectroscopy with a helium-filled proportional counter

R. Katano, T. Fujii, T. Kobayashi, K. Fukumura, Y. Isozumi

Nuclear Inst. and Methods in Physics Research, A 280 ( 2-3 ) 285 - 287 1989年8月

掲載種別：研究論文（学術雑誌）

As studied in our previous works, a proportional counter filled with pure helium gas works well at low temperatures near 4.2 K. The helium-filled proportional counter (HFPC) provides us with a new method to detect nuclear radiations at low temperatures. A typical application of this counter is resonance-electron Mössbauer spectroscopy (REMS) at low temperatures (< ∼ 30 K). In this article some examples of REMS measurements with HFPC are given. © 1989.

DOI： 10.1016/0168-9002(89)90918-2

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