研究者詳細 - 伊藤　恵司

Atomic structure of hydrogen storage amorphous alloys

T. Fukunaga, K. Itoh, K. Aoki

Materials Science Forum 502 257 - 262 2005年

記述言語：英語

Neutron diffraction is a powerful tool to elucidate the structure of hydrogen storage materials. H/D isotopic substitution was employed to observe the location of deuterium atoms because the coherent scattering length of deuterium is large enough to observe in comparison with those of the other atoms forming hydride materials. The combination of X-ray and neutron diffraction made clear the location of deuterium atoms of the hydrogen induced amorphous alloys experimentally. Moreover, the RMC modeling based on the diffraction data indicates that about 93% of D atoms for a-(Ti0.676Zr 0.324)D0.31 and about 98% of D atoms for a-TbFe 2D3.8 and a-TbNi2D2.4 occupy tetrahedral sites formed by metal atoms. Interestingly, during the HJA process, whereas the concentration fluctuation develops in the structure of A-TbFe 2D3.0, the homogeneity of the atomic arrangement of metal atoms is kept for a-TbNi2D2.4.

DOI： 10.4028/0-87849-980-6.257

28pWE-10 超イオン伝導性ガラスAgI-Ag_2S-AgPO_3の低エネルギー励起(過冷却液体等)(領域12)

岩瀬裕希, 新井正敏, 大友季哉, Kartini E., 伊藤恵司, Levett S., Bennington S. M.

日本物理学会講演概要集 59 ( 1 ) 368 - 368 2004年3月

X-Ray and neutron diffraction studies of atomic scale structures of crystalline and amorphous TbFe2Dx

Keiji Itoh, Kazuyuki Kanda, Kiyoshi Aoki, Toshiharu Fukunaga

Journal of Alloys and Compounds 348 ( 1-2 ) 167 - 172 2003年1月

記述言語：英語

Both X-ray and neutron diffraction techniques were employed in order to elucidate short-range structures of crystalline (c-)TbFe2D3.8 and amorphous (a-)TbFe2Dx (x = 3.0, 2.0) prepared by deuterium absorption of the C15 Laves phase compound TbFe2. Interatomic distances and coordination numbers were derived from the radial distribution functions, RDF(r)s. The RDF(r)s observed by X-ray diffraction indicated that c-TbFe2D3.8 adopts a rhombohedral structure, but there is a little difference in the arrangement of metal atoms between the original C15 Laves phase c-TbFe2 and the rhombohedral c-TbFe2D3.8. In contrast, our results indicated that there is a large difference in the arrangement of metal atoms between c-TbFe2 and a-TbFe2Dx (x = 3.0, 2.0) and there are clusters of Fe and Tb atoms in a-TbFe2Dx (x = 3.0, 2.0). RDF(r)s observed by the neutron diffraction indicated that the D atoms occupy tetrahedral sites consisting of 2Tb + 2Fe in c-TbFe2D3.8, while they occupy sites consisting of 4Tb, 3Tb + 1Fe and 2Tb + 2Fe in a-TbFe2Dx (x = 3.0, 2.0). © Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0925-8388(02)00842-3

Structure of amorphous P-Se prepared by mechanical alloying

K. Itoh, M. Misawa, T. Fukunaga

Journal of Non-Crystalline Solids 312-314 561 - 565 2002年10月

記述言語：英語

The short- and medium-range structures of amorphous P1-xSex (x = 0.6, 0.8) synthesized by mechanical alloying (MA) have been investigated by time-of-flight neutron diffraction. The first diffraction peak, near Q = 12 nm-1 in the structure factor, S(Q), which is strongly related to the medium range order, is smaller in height and broader in width than that for amorphous P1-xSex (x = 0.6, 0.8) prepared by liquid quenching. The formation of the medium-range order is restrained when the amorphous P-Se is synthesized by MA. © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(02)01772-6

Short range structures of amorphous Se-Te prepared by mechanical alloying

K Itoh, M Misawa, T Fukunaga

JOURNAL OF NON-CRYSTALLINE SOLIDS 293 575 - 579 2001年11月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

The time-of-flight neutron scattering measurement was employed in order to elucidate the short range structures for a series of amorphous Se100-xTex (x = 0 similar to 20) mixtures synthesized by mechanical alloying (MA). The first peak in the radial distribution functions was resolved into two Gaussian peaks, which correspond to the Se-Se and Se-Te correlations, respectively. Amorphous Se prepared by MA has a lot of dangling bonds. In contrast, for the Se100-xTex samples, Te atoms are preferentially bonded with the dangling bonds of Se atoms with increasing Te concentration and, consequently, a twofold chain structure is formed. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0022-3093(01)00780-3

Neutron diffraction of amorphous Se-Te prepared by MA

K. Itoh, M. Misawa, T. Fukunaga

Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy 48 ( 9 ) 806 - 809 2001年

記述言語：日本語出版者・発行元：Funtai Funamtsu Yakin Kyokai/Japan Soc. of Powder Metallurgy

Amorphous Se100-xTex powders (x = 0, 5, 10, 15 and 20) have been produced by mechanical alloying (MA). The time-of-flight neutron scattering measurement was employed in order to elucidate the short range structures for these powders. Well-resolved first peak in radial distribution functions can be decomposed into two Gaussian peaks, which correspond to the Se-Se and Se-Te correlations. The coordination number teaches us that amorphous Se has a lot of dangling bonds due to broken of Se-Se bond by milling. However, the compositional changes of the coordination numbers of Se-Se and Se-Te pairs for Se-Te powders imply that Te atoms are bonded to the edge of Se chain molecules and the twofold chain structure is built up with increasing Te content.

DOI： 10.2497/jjspm.48.806

メカニカルアロイングにより作製されたアモルファスSe-Teの構造(共著)

ITOH K, MISAWA M, FUKUNAGA T

Journal of Non-Crystalline Solids 293/295 575 - 579 2001年

25aTF-10 アモルファスSe-Te合金の局所構造

伊藤恵司, 三沢正勝, 福永俊晴

日本物理学会講演概要集 55 ( 2 ) 684 - 684 2000年9月

Neutron diffraction of liquid Sn-Se system

K Itoh, K Maruyama, M Misawa, S Tamaki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 69 ( 6 ) 1717 - 1722 2000年6月

記述言語：英語出版者・発行元：PHYSICAL SOC JAPAN

The time-of-flight neutron scattering measurements have been carried out for liquid Sn-Se system. A distinct change in structural properties has been observed between Sn70Se30 and Sn60Se40, composition of which corresponds to that of maximum of the miscibility gap. The atomic configuration of liquid SnSe have been compared to that of molten NaCl. It is found that the bonding nature between Sn and Se in liquid SnSe is ionic rather than covalent. A small but apparent pre-peak at Q = 1.2 Angstrom(-1) in the structure factor for liquid SnSe2 is found above the melting point. It suggests that the network structure remains after melting. The intensity of this pre-peak decreases with increasing temperature, indicating that the network structure is destroyed.

DOI： 10.1143/JPSJ.69.1717

30p-G-5 液体Sn-Se系の中性子回折

伊藤恵司, 丸山健二, 三沢正勝, 田巻繁

日本物理学会講演概要集 54 ( 1 ) 515 - 515 1999年3月

Ionic and Electronic Conductions in Liquid Metal-Charcogen System.

Journal of Non-Crystalline Solids 250/252 ( Pt.1 ) 336 - 339 1999年

Magnetic susceptibility in liquid In-Se system

K Itoh, T Usuki, S Tamaki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 67 ( 9 ) 3240 - 3243 1998年9月

記述言語：英語出版者・発行元：PHYSICAL SOC JAPAN

The magnetic susceptibility of the liquid In1-xSex system have been measured as functions of concentration and temperature. The magnetic susceptibility of the system shows a broad diamagnetic maximum near x=0.58. This behaviour corresponds to the concentration variation of electronic conductivity reported previously and supports our previous suggestion of the valence fluctuation of In ions. By using the data of magnetic susceptibility with known electronic conductivity and thermoelectric power data, the density of state N(E) have been determined and the diamagnetic susceptibility due to ion core, chi(d), has also been obtained. The obtained value of chi(d) suggests the occurrence of monovalent In ion near the composition x=0.58.

DOI： 10.1143/JPSJ.67.3240

Electronic and Ionic Conductions in Liquid Cu–Se System

Itoh Keiji, Usuki Takeshi, Tamaki Shigeru

Journal of the Physical Society of Japan 67 ( 10 ) 3512 - 3516 1998年

記述言語：英語出版者・発行元：一般社団法人日本物理学会

Electronic and ionic conductivities of liquid Cu–Se system have been measured as a function of concentration and temperature. The electronic conductivity, σe, in the system shows a broad minimum near the composition Cu2Se and the ionic conductivity, σi, has a maximum around this composition. In Se-rich region, a change from negative to positive temperature dependence of σe and a discontinuous jump in σi have been observed at a certain temperature. The relation between the electronic and ionic conductivities have quantitatively been discussed.

DOI： 10.1143/JPSJ.67.3512

CiNii Books

液体In-Se系の磁化率

Journal of the Physical Society of Japan 67 ( 9 ) 3240 - 3243 1998年

液体In-Se系のイオン伝導と電子的性質

Itoh Keiji, Usuki Takesi, Tamaki Shigeru

Journal of the Physical Society of Japan 67 ( 7 ) 2415 - 2420 1998年

記述言語：英語出版者・発行元：一般社団法人日本物理学会

Electronic and ionic conductivities and thermoelectric power of liquid In1-x–Sex system have been measured as a function of concentration and temperature. The electronic conductivity in the system shows a deep minimum near the Se composition x=0.58 and the ionic conductivity has a broad maximum at this composition, where the thermoelectric power shows a large negative maximum. The electronic conductivity and thermoelectric power were analyzed in terms of the Fermi-Dirac integrals. It is found that the shape of the density of state, N(E), changes gradually with concentration.

DOI： 10.1143/JPSJ.67.2415

CiNii Books

Ionic Conduction and Electronic Properties in Liquid In–Se System

その他リンク： https://jlc.jst.go.jp/DN/JALC/00054433311?from=CiNii

Itoh Keiji, Usuki Takesi, Tamaki Shigeru

Journal of the Physical Society of Japan 67 ( 7 ) 2415 - 2420 1998年

記述言語：英語出版者・発行元：一般社団法人日本物理学会

DOI： 10.1143/JPSJ.67.2415

CiNii Books

その他リンク： https://jlc.jst.go.jp/DN/JALC/00054433311?from=CiNii

28p-X-1 砒素-カルコゲン系液体合金の局所構造

臼杵毅, 伊藤恵司, 植村治, 亀田恭男

日本物理学会講演概要集 52 ( 1 ) 531 - 531 1997年3月

溶融(In_<1/2>Pb_<1/2>)-Te系の構造と電子的性質

伊藤恵司, 臼杵毅, 植村治, 亀田恭男

日本物理学会講演概要集. 秋の分科会 1995 ( 3 ) 288 - 288 1995年9月

NEUTRON-DIFFRACTION STUDY OF LIQUID (TL1/2PB1/2)-X (X-TE,SE) SYSTEMS

T USUKI, O UEMURA, K ITOH, Y KAMEDA

PHYSICA B 213 555 - 557 1995年8月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

Neutron diffraction measurements have been carried out on liquid (TI1/2Pb1/2)(1-y)X(y)(X:Te,Se) systems which exhibit a typical compound-forming behaviour at y = 3/7. Radial distribution analysis at y = 3/7 has indicated that the bonding nature of T1-X and Pb-X is more or less ionic, as expected from the previous result of electronic properties. In order to investigate the difference in electronic behaviour between these two liquid systems in the chalcogen rich region, we derive the X-X partial distribution function g(X-X)(r), assuming that each partial function at y > 3/7 is independent of the alloy composition. g(Se-Se)(r) has a well-resolved first peak at r similar to 0.230 nm, suggesting that covalent Se-Se bonds appear in the Se rich region. On the other hand, g(Te-Te)(r) is somewhat structureless, although the first peak is included in the covalent region. The whole functional form of both g(X-X)(r) is roughly similar to that of g(r) in pure liquid Te or Se.

ELECTRONIC AND STRUCTURAL-PROPERTIES OF THE LIQUID (TL1/2PB1/2)-SE SYSTEM

T USUKI, K ITOH, S AITA, Y KAMEDA, O UEMURA

PHYSICA STATUS SOLIDI B-BASIC RESEARCH 187 ( 1 ) 157 - 168 1995年1月

記述言語：英語出版者・発行元：AKADEMIE VERLAG GMBH

The electrical conductivity, magnetic susceptibility, and thermoelectric power in the liquid (Tl1/2Pb1/2)-Se system are measured over wide temperature and composition ranges. It is observed that the electrical conductivity in the system sharply falls near the stoichiometric composition of Tl2Pb2Se3 and the magnetic susceptibility has a diamagnetic maximum at this composition, where the thermoelectric power changes its sign. In addition, the DTA investigation shows that the liquidus temperature of the system has a maximum around this composition. These results suggest that a short-range order appears around the composition of Tl2Pb2Se3 in the liquid (Tl1/2Pb1/2)-Se system. The delocalized electron analysis using both susceptibility and conductivity data suggests that the bonding nature of liquid Tl2Pb2Se3 is rather ionic. The radial distribution study by neutron diffraction also exhibits that the first peak position of g(r) for liquid Tl2Pb2Se3 is located near the ionic bond distance of metal and chalcogen atoms. On the other hand, covalent Se-Se bonds are formed in the Se-rich composition range.

DOI： 10.1002/pssb.2221870115