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 57, Issue 3
March
Displaying 1-10 of 10 articles from this issue
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Paper
Paper
  • The Control Method of Porous Structure for Density Gradient Materials in Direct Metal Laser Sintering (DMLS)
    Hyun-Goo Kang, Toshiko Osada, Fujio Tsumori, Hideshi Miura
    2010 Volume 57 Issue 3 Pages 147-151
    Published: 2010
    Released on J-STAGE: May 07, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.147
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    The effect of process parameters in direct metal laser sintering (DMLS) on the forming of density gradient porous structure was investigated. The melted and consolidated parts of metallic powders by laser irradiation (it is called as melted part in this paper) sparsely form along the laser scanning line. The size of melted part strongly depends on the laser input energy. During the direct metal laser sintering, the melted parts conglutinate with each other and made the larger melted part. It was connected to other melted parts in different way by strong laser power and high scan rate. Especially, in the case of same laser energy density, if the scan rate become faster, the connection between melted parts gets stronger and the high density is obtained. With laser sintering condition for similar relative density, the microstructure of material formed by higher scan rate shows more homogeneous microstructure than that of the others formed by slow scan rate.
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  • Purification of Silicon Grinding Sludge by Spark Plasma Sintering
    Naomichi Sakamoto, Takuya Yasuno, Kiminori Gemba, Yusuke Matsumiya, Ma ...
    2010 Volume 57 Issue 3 Pages 152-157
    Published: 2010
    Released on J-STAGE: May 07, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.152
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    Recycling possibilities of silicon grinding sludge using spark plasma sintering (SPS) method were investigated. The silicon grinding sludge taken out from wastewater in silicon wafer production process was sintered by the SPS method. Sintering experiment results showed that production of sintered compacts was possible from the silicon sludge by SPS. Density and hardness of sintered compacts were increased with both sintering temperature and holding time. Results of composition analyses indicated that the sintering increased silicon purity of the compacts due to decreasing oxygen content. The content of silicon in the sintered compact was increased up to about 20 mass% compared with that in the silicon sludge. XRD analysis suggested also decreasing oxygen content by the sintering. Therefore, it was revealed that higher-purity silicon sintered compacts were produced by sintering of the silicon sludge with the SPS method in our study.
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Special Issue: Transition-Metal (including Rare Earth Elements) Compounds Generating Novel Electronic Properties
Summarization
Review
Paper
  • Magnetic Properties of Single Crystals of Pseudobinary Fe1-xCoxTe0.85 System
    Jinhu Yang, Mami Matsui, Hiroto Ohta, Chishiro Michioka, Kazuyoshi Yos ...
    2010 Volume 57 Issue 3 Pages 166-171
    Published: 2010
    Released on J-STAGE: May 07, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.166
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    Single crystals of Fe1-xCoxTe0.85 have been synthesized successfully with x = 0, 0.02, 0.03, 0.05 and 0.10. The cobalt can be substituted for the iron site as Fe1-xCoxTe0.85 up to a solubility limit of x = 0.10, above which an impurity phase was observed. We obtained the intrinsic susceptibilities of these samples by Honda-Owen plot. The antiferromagnetic transition temperature decreases from about 70 K (x = 0) to 34 K (x = 0.05) with increasing the Co substitution level. Superconductivity was not discovered in this series, but a spin-glass like behavior was observed in 5 % substituted sample.
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  • Synthesis and Magnetic Properties of the Layered Compound Fe3GeTe2
    Bin Chen, JinHu Yang, Hiroto Ohta, Chishiro Michioka, Kazuyoshi Yoshim ...
    2010 Volume 57 Issue 3 Pages 172-176
    Published: 2010
    Released on J-STAGE: May 07, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.172
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    Fe3GeTe2 was synthesized by solid state reaction and chemical transport methods. Our magnetic measurements show that it is a ferromagnet with the Curie temperature of 226 K. The Rhodes-Wohlfarth ratio Pc/Ps∼6.6 indicates that it is an itinerant ferromagnet. On the other hand, we found the single crystal sample with the Curie temperature of 146 K shows the large anisotropy in the temperature dependence of magnetic susceptibilities and the magnetization curves when the external magnetic fields are applied along the c axis and within the ab plane.
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  • Study of Magnetic Properties of Layered Compound LaCoAsO and its Related Compounds
    Hiroto Ohta, Bin Chen, Jinfu Yang, Chishiro Michioka, Kazuyoshi Yoshim ...
    2010 Volume 57 Issue 3 Pages 177-180
    Published: 2010
    Released on J-STAGE: May 07, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.177
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    We successfully synthesized itinerant-electron ferromagnetic compound LaCoAsO and studied its magnetic properties based on the self-consistent renormalization theory of spin fluctuations and Takahashi's spin-fluctuation theory. We showed that the magnetization (M) of LaCoAsO shows the convex behavior when plotted in the form of M 2 vs H/M, while the M 4 shows the almost linear relation against H/M, which is predicted in the Takahashi's theory. From the comparison between the experimentally observed magnetic susceptibility and calculated one by using the self-consistent renormalization theory, we showed that the nature of spin fluctuations is 3-dimensional around the Curie temperature TC, while above 3TC the difference between two susceptibilities becomes more prominent with increasing temperature, indicating that 2-dimensional spin fluctuations dominate over the 3-dimensional ones in the high temperature region.
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  • Novel Iron Oxides with Square Planar Coordination from Low Temperature Synthesis
    Cédric Tassel, Yoshihiro Tsujimoto, Hiroshi Kageyama, Kazuyoshi ...
    2010 Volume 57 Issue 3 Pages 181-185
    Published: 2010
    Released on J-STAGE: May 07, 2010
    DOIhttps://doi.org/10.2497/jjspm.57.181
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    By using new synthetic approaches, one can create new families of materials which could lead to new chemical and physical properties. From this philosophy, we have synthesized novel iron oxides by topochemically extracting oxygen from well known perovskites derivatives SrFeO3, layered Sr3Fe2O7 and brownmillerite CaFeO2.5. The new materials SrFeO2, Sr3Fe2O5 and CaFeO2 possess FeO4 square planes and derivatives. These novel materials show new structures in which exotic electronic and magnetic properties can be witnessed. They also provide clues to understand oxygen diffusion in solids. In this review, we describe the chemical and physical properties of these novel iron oxides.
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