Faculty Profiles - SAITO Masatoshi

Effective Pair Potentials of Molten AgBr Estimated from Experimental Partial Structure Factors

Structural characterization for a complex system by obtaining middle-range ordering Reviewed

Yoshio Waseda, Shigeru Suzuki, Masatoshi Saito

Characterization of Corrosion Products on Steel Surfaces 7 77 - 104 2006

Quasimonochromatic x-ray computed tomography by the balanced filter method using a conventional x-ray source Reviewed

M Saito

MEDICAL PHYSICS 31 ( 12 ) 3436 - 3443 2004.12

Fe (O, OH)(6) network structure of rusts formed on weathering steel surfaces

M Kimura, T Suzuki, G Sigesato, M Saito, S Suzuki, H Kihira, K Tanabe, Y Waseda

JOURNAL OF THE JAPAN INSTITUTE OF METALS 66 ( 3 ) 166 - 175 2002.3

MITEV Pavlin Dakev, SAITO Masatoshi, WASEDA Yoshio

MATERIALS TRANSACTIONS 42 ( 5 ) 829 - 832 2001.5

Language：English Publisher：The Japan Institute of Metals and Materials

Three effective pair potentials of Ag–Br, Br–Br and Ag–Ag pairs in molten AgBr have been calculated from measured partial structural data by applying the modified hypernetted-chain equation coupled with a predictor-corrector method. The present results of pair potentials were also compared with model potentials originally proposed by Vashishta and Rahman. The resultant potentials suggest two characteristic features. One is the relatively shallow minimum in the interaction of Ag–Br pair in the first nearest neighbor region at 0.27 nm, in comparison with the model potential case. The other is both positive and negative deviation from the simple asymptotic form detected in the interaction of Br–Br pair in the range of 0.3&sim;1.1 nm. These results may be attributed to a particular structural feature of molten AgBr, suggesting not only the purely ionic character.

DOI： 10.2320/matertrans.42.829

Transport Properties of Superionic Conducting Glasses (AgX)_<0.4>(Ag_2O)_<0.3>(GeO_2)_<0.3> (X=I, Br, Cl)

KANG Shinchul, SAITO Masatoshi, JACOB K. Thomas, WASEDA Yoshio

Materials Transactions, JIM 41 ( 12 ) 1670 - 1674 2000.12

Language：English Publisher：The Japan Institute of Metals

In order to identify the dominant mechanism of ionic conduction, the electrical conductivity and ionic mobility of the glasses (AgX)0.4(Ag2O)0.3(GeO2)0.3 (X=I, Br, Cl) were measured separately in the temperature range from 293 to 393 K by coupling the AC technique with the TIC method. Electronic conductivity was also measured at 293 K by the Wagner polarization method. The total electrical conductivity of these glasses was found to be as high as 10−1 Ω−1 m−1, and the mobility about 10−6 m2 V−1 s−1. The variation of total electrical conductivity and mobility at constant temperature and composition with the type of halide occurred in the sequence, Cl<Br<I. For each composition, both conductivity and mobility increased with temperature. The mobile ion concentration was found to be about 1023 m−3 at 293 K, and it was insensitive to the type of halide as well as temperature. The results suggest that the change in ionic conductivity with the temperature and the type of halide present is mainly attributable to the change in ionic mobility rather than carrier concentration. Moreover, the electronic conductivity was found to be about 10−6 Ω−1 m−1 at 293 K. Thus, the electronic contribution to the total conductivity is negligibly small.

DOI： 10.2320/matertrans1989.41.1670

Partial structural functions of molten copper halides CuX (X = Br, I) estimated from the anomalous x-ray scattering measurements

Y. Waseda, S. Kang, K. Sugiyama, M. Kimura, M. Saito

Journal of Physics Condensed Matter 12 2000.12

Structural Study of Amorphous Ge 50Al 40Cr 10 Alloy

Louzguine Dmitri, Saito Masatoshi, Waseda Yoshio, Inoue Akihisa

J Phys Soc Jpn 68 ( 7 ) 2298 - 2303 1999.7

Language：English Publisher：The Physical Society of Japan (JPS)

The structure of an amorphous Ge50Al40Cr10 alloy was studied by conventional X-ray diffraction, anomalous X-ray scattering and transmission electron microscopy including high-resolution imaging. The anomalous X-ray scattering profiles were obtained at Ge and Cr K-absorption edges. Structural information in the form of interference function obtained by the experimental methods was checked for its correctness by using the reverse Monte Carlo simulation method. The structure of the alloy studied is discussed on the basis of transmission electron microscopy images, an ordinary radial distribution function, partial structure functions and partial pair distribution functions.

DOI： 10.1143/JPSJ.68.2298

Partial structural functions of molten AgBr estimated from the anomalous X-ray scattering data coupled with neutron diffraction

Other Link： https://jlc.jst.go.jp/DN/JALC/00062001304?from=CiNii

Masatoshi Saito, Shinchul Kang, Kazumasa Sugiyama, Yoshio Waseda

Journal of the Physical Society of Japan 68 ( 6 ) 1932 - 1938 1999.1

Structure and Magnetic Properties of La(Co1-xMnx)13 Crystlline and Amorphous Alloys

K. Asada, A. Fujita, S.G. Kim, K. Fukamichi, E. Matsubara, M. Saito, Y. Waseda

J. Magn. Soc. Jpn. 23 480 - 482 1999

Structural Study of Pd-Based Amorphous Alloys with Wide Supercooled Liquid Region by Anomalous X-ray Scattering

Park Changyong, Saito Masatoshi, Waseda Yoshio, Nishiyama Nobuyuki, Inoue Akihisa

Materials Transactions, JIM 40 ( 6 ) 491 - 497 1999

Language：English Publisher：The Japan Institute of Metals

The anomalous X-ray scattering (AXS) measurements have been made to determine the local ordering structures around Ni and Cu in Pd40Ni10Cu30P20 and Pd40Ni40P20 alloys in both the liquid and amorphous state using the synchrotron radiation at incident X-ray energies close to the K-absorption edges of Ni and Cu. A characteristic small hump was clearly found at r=0.37 nm in the environmental radial distribution function (RDF) around Cu in liquid and amorphous Pd40Ni10Cu30P20 alloy. Such peak was not detected in the environmental RDF around Ni, and the local atomic arrangement around Ni was found to be similar to the Pd40Ni40P20 case. These experimental facts can be described when considering the trigonal prismatic packing related to Ni and the tetragonal dodecahedral packing related to Cu. This is in a sense a necessary condition at best, although it might not be the sufficient condition. However, the effect of elemental substitution with Cu for Ni in the Pd–Ni–Cu–P alloy is thought to induce the particular atomic association related to Cu, which is an important factor for exhibiting its wide supercooled liquid region and high reduced glass transition temperature.

DOI： 10.2320/matertrans1989.40.491

Effective Pair Potentials of Liquid CuBr Estimated from the Anomalous X-Ray Scattering Data

Omote Kazuhiko, Saito Masatoshi, Waseda Yoshio

J Phys Soc Jpn 66 ( 10 ) 3097 - 3101 1997.10

Language：English Publisher：The Physical Society of Japan (JPS)

We have proposed a method for calculating the effective pair potentials of molten salt from measured structural data in which a long-range Coulombic interaction is important [K. Omote and Y. Waseda: J. Phys. Soc. Jpn. 66 (1997)]. By applying this method, the effective pair potentials of liquid CuBr have been successfully estimated from the experimental partial structure factors obtained by anomalous X-ray scattering. The resultant potentials show two characteristic features. One is remarkable shielding for the Cu–Cu Coulomb repulsion in its nearest neighbor region. This might be a possible origin for the absence of marked structure in the Cu–Cu correlation and the penetration of Cu ions into the first like-ion coordination shell. The other is the deviation from the Coulomb potential in the range of 0.4∼0.9 nm in the interactions of Cu–Cu and Cu–Br pairs, suggesting a certain correlation to a pre-peak found in the Cu–Cu structure factor at about 10 nm-1.

DOI： 10.1143/JPSJ.66.3097

Structure Analysis of Disordered Materials by the Anomalous X-ray Scattering(AXS) Method. Reviewed

Other Link： https://jlc.jst.go.jp/DN/JALC/00049510119?from=CiNii

SUGIYAMA Kazumasa, SAITO Masatoshi, WASEDA Yoshio, MATSUBARA Eiichiro

Nihon Kessho Gakkaishi 39 ( 1 ) 20 - 25 1997.2

Language：Japanese Publisher：The Crystallographic Society of Japan

The anomalous X-ray scattering method has recently received much attention for obtaining the fine structure of disordered materials, coupled with the synchrotron radiation source. This paper demonstrates the usefulness of the AXS method for determining the local environmental structure around a specific element as a function of distance, by providing fundamentals with some selected examples of high temperature CuBr liquid, 70GeO230Bi2O3 oxide glass and Zr-Y-Al-Ni metallic glasses.

DOI： 10.5940/jcrsj.39.20