Journal of the Japan Society of Powder and Powder Metallurgy
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
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Volume 55, Issue 2
February
Displaying 1-16 of 16 articles from this issue
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Paper
Rapid Communication
  • Rapid Preparation of Bi2Sr2CaCu2Oy by Using a Domestic Microwave Oven with a SiC susceptor
    Yusuke Okano, Toshiki Nakamura, Yoshitaka Inou, Tomohiro Ando, Kentaro ...
    Article type: Rapid Communicatin
    2008 Volume 55 Issue 2 Pages 85-89
    Published: 2008
    Released on J-STAGE: October 08, 2008
    DOIhttps://doi.org/10.2497/jjspm.55.85
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    Nearly single-phase samples of high-Tc superconductors of the Bi-2212 phase have been prepared using a domestic microwave oven. Since it is to be important for the preparation to control the temperature of the sample environment, the samples were placed into thermally insulated box whose inner surface is made by SiC. An industrial microwave (2.45 GHz) furnace was used with repeating the microwave radiation processes with intermediate grinding. The comparison among microstructures of the samples obtained by domestic and industrial microwave ovens as well as those of TSFZ single crystals and polycrystals by solid state method was reported.
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Paper
  • Effects of Mechanical Milling with Ag Powder on Thermoelectric Properties of NaxCo2O4 Polycrystal Synthesized through Citric Acid Complex Process
    Mikio Ito, Junji Sumiyoshi
    Article type: Paper
    2007 Volume 55 Issue 2 Pages 90-95
    Published: 2007
    Released on J-STAGE: October 08, 2008
    DOIhttps://doi.org/10.2497/jjspm.55.90
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    NaxCo2O4 powders synthesized by citric acid complex (CAC) process were mechanically milled with Ag particles around 1μm in size and then pressurelessly sintered. Effects of the mechanical milling on microstructure and thermoelectric properties of a NaxCo2O4/Ag composite were investigated. Ag powder was finely dispersed in the NaxCo2O4/Ag mixed powder after mechanical milling. The NaxCo2O4/Ag sintered bodies showed the large crystallographic anisotropy as compared to the NaxCo2O4/Ag composite synthesized by the conventional CAC process. However, Ag particles were coarsened during sintering, and the NaxCo2O4/Ag composite polycrystal with dispersion of fine Ag grains could not be obtained. By Ag addition, the electrical resistivity was significantly reduced, but the thermal conductivity was increased because of the coarse Ag phase, resulting in the dimensionless figure of merit almost the same as, or smaller than, that of the sample without Ag.
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  • Thermal Conductivity of Diamond Particle Dispersed Aluminum Matrix Composites Produced in Solid-Liquid Co-Existent State by SPS
    Kiyoshi Mizuuchi, Kanryu Inoue, Yasuyuki Agari, Yoshiaki Morisada, Mas ...
    Article type: Paper
    2008 Volume 55 Issue 2 Pages 96-100
    Published: 2008
    Released on J-STAGE: October 08, 2008
    DOIhttps://doi.org/10.2497/jjspm.55.96
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    Diamond-particle-dispersed-aluminum (Al) matrix composites were fabricated in solid-liquid coexistent state by Spark Plasma Sintering (SPS) process from the mixture of diamond and pure Al powders and that of diamond and 5056-type Al-Mg alloy powders. The microstructures and thermal conductivities of the composites fabricated were examined. These composites were all well consolidated at 813K for 2.1ks in SPS process. No reaction at the interface between the diamond particle and the Al matrix was observed by scanning electron microscopy for the composites fabricated under the sintering conditions employed in the present study. The relative packing density of the diamond-Al composite fabricated was 97% or higher in a volume fraction range of diamond between 25 and 45.5%. Thermal conductivity of the diamond-Al composite containing 45.5 vol.% diamond reached 403W/mK, approximately 76% the theoretical thermal conductivity estimated using Maxwell-Euckenís equation.
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  • Preparation and Luminescent Properties of Delafossite-Type CuLaO2 Doped with II-Group Elements
    Akinori Katsui, Yuhsuke Takahashi, Hiroaki Matsushita
    Article type: Paper
    2008 Volume 55 Issue 2 Pages 101-105
    Published: 2008
    Released on J-STAGE: October 08, 2008
    DOIhttps://doi.org/10.2497/jjspm.55.101
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    Single-phase delafossite-type CuMxLa1-xO2 (M=Mg, Ba, Ca, Sr, Mg, Zn, Cd) was synthesized by means of the solid-state reaction of a stoichiometrically mixed powder of binary oxides at 1273 K, for 10 h in an argon flow, and their luminescent properties were investigated. Undoped CuLaO2 exhibited a weak yellow-green photoluminescence-emission band due to the Cu+ interconfiguration transition at room temperature. The effect of II-group element doping on the photoluminescent properties was classified into two types. CuSrxLa1-xO2, CuBaxLa1-xO2 and CuZnxLa1-xO2 (x≤0.01) exhibited the emission slightly shifted to the shorter-wavelength side than that of undoped CuLaO2 and a strong emission intensity, with increasing doping concentration. These emission behaviors in CuSrxLa1-xO2, CuBaxLa1-xO2 and CuCaxLa1-xO2 was considered to be due to the formation of new emission centers upon doping Sr, Ba and Ca, respectively. CuZnxLa1-xO2, CuCdxLa1-xO2 and CuMgxLa1-xO2 (x≤0.01) exhibited the emission similar to one due to the Cu+ interconfiguration transition in undoped CuLaO2 and a weaker emission intensity, with increasing doping.
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Special Issue:Magnetic Materials for Most-advanced Applicaions
Summarization
Review
  • Formation and Developments of Spintronics Research Field
    Terunobu Miyazaki, Mikihiko Oogane, Yuuya Sakuraba, Daisuke Watanabe, ...
    Article type: Review
    2008 Volume 55 Issue 2 Pages 109-115
    Published: 2008
    Released on J-STAGE: October 08, 2008
    DOIhttps://doi.org/10.2497/jjspm.55.109
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    History about the research of magnetoresistance effect was reviewed. Also, we looked back on the research trends in the past when both giant magnetoresistance of Fe/Cr multi layered films and large tunnel magnetoresistance at room temperature were found.
    Special emphasis was placed on the recent developments of huge TMR ratio for both MgO barrier tunnel junctions and Heusler alloy electrode tunnel junctions which contribute further to the development of spinelectronic research fields. Principle and importance of spin-transfer torque were also explained.
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Paper
  • Improvements in Crystallinity of MgO Barrier Layer and FeCo Spin Polarization Enhancement Layer for Perpendicular MRAM
    Hideto Ohmori, Tomoya Hatori, Shigeki Nakagawa
    Article type: Paper
    2008 Volume 55 Issue 2 Pages 116-120
    Published: 2008
    Released on J-STAGE: October 08, 2008
    DOIhttps://doi.org/10.2497/jjspm.55.116
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    Rare-earth-transition metal (RE-TM) alloy films, such as TbFeCo and GdFeCo layers were used as perpendicularly magnetized layers for pinned and free layers in a perpendicular magnetic tunneling junction (p-MTJ). (100) oriented MgO tunneling barrier layer can be deposited on (100) oriented Fe (and FeCo) buffer layers. The (100) texture of the Fe (and FeCo) layers were enhanced by depositing them on the RE-TM layers. X-ray diffraction study clarified that MgO layers deposited on the Fe (and FeCo) layers revealed apparent (100) orientation at the early stage of the film growth. 3nm-thick MgO layer deposited on GdFeCo(100nm)/Fe(3nm) exhibited (100) texture.
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  • Fabrication of Ultra Thin fct-FePt (001) Ordered Alloy Thin Films from Pt/Fe Bilayers for Perpendicular Magnetic Recording Media
    Jun-ichi Ikemoto, Shigeki Nakagawa
    Article type: Paper
    2008 Volume 55 Issue 2 Pages 121-126
    Published: 2008
    Released on J-STAGE: October 08, 2008
    DOIhttps://doi.org/10.2497/jjspm.55.121
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    Pt(3nm)/Fe(3nm) bilayered films deposited directly on glass disk substrates at room temperature exhibited preferential (100) orientation in Pt as well as Fe layers because of a hetero epitaxial growth from the bottom Fe(100) to the top Pt(100) textures. Highly ordered fct-FePt(001) alloy texture was appeared in the bi-layered film after annealed at 600°C in hydrogen atmosphere. Increase of substrate temperature up to 600°C during the deposition of 3nm-thick Pt layer on the Fe layer brought about a direct fabrication of fct-FePt(001) ordered alloy thin film.
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  • High Frequency Characteristics of FeCoB/NiFe/Si Thin Films with Resonance Frequency in the GHz Range
    Toshimitsu Matsuu, Atsuto Hashimoto, Shigeki Nakagawa
    Article type: Paper
    2008 Volume 55 Issue 2 Pages 127-131
    Published: 2008
    Released on J-STAGE: October 08, 2008
    DOIhttps://doi.org/10.2497/jjspm.55.127
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    Recently the development of the magnetic devices has been expected in the high frequency applications. The soft magnetic films with large saturation magnetization and high anisotropy field Hk have been required. In this study, FeCoB/NiFe/Si thin films deposited by Facing Targets Sputtering (FTS) system have saturation magnetization of 2 T and Hk of 20 kA/m, and exhibited high ferromagnetic resonance (FMR) frequency of 6.0-7.0 GHz in permeability characteristics. For improvement of high frequency permeability characteristics, we reduced the thickness of FeCoB soft magnetic layer. The results showed that damping constant was reduced and exhibited smaller loss capability. When changing of the FeCoB thickness, we investigated the change of anisotropy field Hk and FeCoB(110) lattice spacing in the perpendicular direction, which indicated that there was correlation between each other. From this relationship, we examined the origin of anisotropy field Hk.
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  • Ferromagnetic Cuprates, CaCu3Ge4O12 and CaCu3Sn4O12, with A-site Ordered Perovskite Structures
    Hiroshi Shiraki, Takashi Saito, Takahiro Yamada, Masahiko Tsujimoto, M ...
    Article type: Paper
    2008 Volume 55 Issue 2 Pages 132-136
    Published: 2008
    Released on J-STAGE: October 08, 2008
    DOIhttps://doi.org/10.2497/jjspm.55.132
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    We succeeded in synthesizing A-site ordered perovskites, CaCu3Ge4O12 and CaCu3Sn4O12, under high pressure and high temperature conditions. The magnetic measurements revealed that these compounds are ferromagnets in contrast to the isostructural antiferromagnet, CaCu3Ti4O12. The ferromagnetism in CaCu3Ge4O12 and CaCu3Sn4O12 comes from the special alignment of CuO4 planes in the perovskite structure. On the other hand, the involvement of Ti-3d orbitals in magnetic interactions give rise to the antiferromagnetic superexchange interaction and it overcomes the ferromagnetic direct interaction in CaCu3Ti4O12. The finding demonstrates that either ferromagnetic or antiferromagnetic behavior can appear within the same structural framework.
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  • Synthesis and Physical Properties of Double Perovskite Pb2FeReO6
    Kousuke Nishimura, Masaki Azuma, Mikio Takano, Yuichi Shimakawa
    Article type: Paper
    2008 Volume 55 Issue 2 Pages 137-140
    Published: 2008
    Released on J-STAGE: October 08, 2008
    DOIhttps://doi.org/10.2497/jjspm.55.137
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    A double perovskite Pb2FeReO6 was prepared at a high pressure (6 GPa) and high temperature (1000°C) condition. The crystal structure determined by the synchrotron X-ray powder diffraction study was centrosymmetric with the space group I4/m despite the presence of Pb2+ ion in the A site. No structural transition to the lower symmetry was observe down to 23 K. This compound exhibited a ferrimagnetic transition at 420 K. The saturation magnetization varied with the degree of Fe3+/Re5+ ordering.
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New Techniques and New Products
New Techniques and New Products
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