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Volume 54, Issue 2
February
Displaying 1-11 of 11 articles from this issue
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Paper
Memorial Lecture of JSPM Award
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Yoshihiro Kusano, Kazuhiro Yamaguchi, Minoru Fukuhara, Akira Doi2007 Volume 54 Issue 2 Pages 75-80
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSThe microstructure and formation process of Hidasuki, a characteristic reddish pattern on traditional Japanese unglazed stoneware called Bizen, was studied through model experiments. Pellets of the Bizen clay mined at Bizen-shi/Okayama pref. were heated to 1250°C with and without rice straw and then cooled at different rates. A reddish color pattern appeared for relatively slowly cooled samples when rice straw was present. Owing to the presence of potassium in the rice straw, mullite (3(Al, Fe)2O3·2SiO2), a major phase formed in the absence of rice straw, was replaced by corundum (α-Al2O3), hematite (α-Fe2O3), and others in the surface region of about 50μm in depth. The corundum precipitated as hexagonal plate-like crystals, and on the edges of these crystals the hematite grew epitaxially. The growth continued so that the primary corundum crystals were wholly covered by hematite to form a specific single crystalline α-Fe2O3/α-Al2O3/α-Fe2O3 structure.View full abstractDownload PDF (900K)
Paper
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Masafumi Shimizu, Toshihiko Sato, Makoto Tsuruoka2007 Volume 54 Issue 2 Pages 81-85
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSRecently, there advances the collaboration of magnetics and life science fields. We focused on iron storage protein ferritin, which has a cavity of 6∼8 nm in a diameter after the removal of iron oxide from inside of it. Magnetic ferritin can be expected when ultrafine cobalt ferrite particle could be included in the cavity of ferritin because balk CoFe2O4 have large magnetocrystalline magnetic anisotropy constant K1 and suitable high magnetization. In this research, the morphology and magnetic properties of ultrafine cobalt particles less than 12 nm in diameter prepared by the coprecipitation method have been investigated. The X-ray diffraction data and TEM observations indicate that cubic-structured spinel particles are formed in granular shape in the reaction condition of pH 9∼13 and the temperatures 60∼105°C. For example, 7.3 nm particles in diameter, which are as small as the diameter of the cavity of ferritin, have been obtained successfully at a pH of 10 at 60°C for 0.5 hour reaction. Saturation magnetization and coercivity of the particles 6∼8 nm are 20∼40 emu/g and are less than 30 Oe at 300 K, respectively. Furthermore, after the removal of iron oxides from ferritin, the inclusion of ultrafine cobalt ferrite particles have been attempted. The change of UV-vis spectrum after the reaction might indicate the inclusion of ultrafine cobalt particle in the cavity of ferritin.View full abstractDownload PDF (683K) -
Kazutomo Abe, Naoto Kitahara, Daiju Sugiyama, Fumiko Morifuji, Mikio H ...2007 Volume 54 Issue 2 Pages 86-92
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSA wide-band electromagnetic wave absorber was developed using a double-layered monolith consisting of high- and low-permeability (μr) composite ceramics. The low-μr layer was formed from a powder mixture of Ni0.7Zn0.1Cu0.2Fe2O4 and SiO2-based glass. Ferrite mixtures of low-firing Ni0.2Zn0.6Cu0.2Fe2O4 and Ni0.3Zn0.7Fe2O4 with less sinterability were used to adjust the densification characteristics of the high-μr layer. Co-firing of green compacts of the ferrite: glass powder (90:10% in mass-base) for the low-μr layer and low-firing ferrite: less-sinterable ferrite (60:40% in mass-base) for the high-μr layer resulted in the production of a monolithic double-layered ceramic at 1100°C. Scanning electron microscopy and electron microprobe analysis of the monolithic double-layered ceramic showed that Ni-Zn interdiffusion and glass diffusion occurred across the layer boundary, leading to the diffusion bonding. An absorption band of the double-layered absorber was more than 10 dB in a wide frequency range from 6 MHz to 1.8 GHz.View full abstractDownload PDF (1045K) -
Katsuomi Shiina, Makoto Sugamata, Junichi Kaneko2007 Volume 54 Issue 2 Pages 93-98
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSWith a purpose of obtaining light weight materials of high strength, powder mixture of aluminum and magnesium silicide (Mg2Si) was mechanically alloyed with addition of oxide (Cr2O3, Fe2O3, MnO2) powder. The mechanically alloyed powders were consolidated to the P/M materials by vacuum hot pressing and hot extrusion, and their structures and mechanical properties were examined and compared with hyper-eutectic Al-Si based P/M materials. All the P/M materials of Al-Mg2Si-oxide showed high compressive strength above 900 MPa. Among them, the highest strength of 1090 MPa was obtained for Al-Mg2Si-Fe2O3. Even the P/M material of Al-Mg2Si without oxide addition showed compressive strength of 795 MPa. The Al-Mg2Si based P/M materials showed higher compressive strength and higher ductility than hyper-eutectic Al-Si based P/M materials.View full abstractDownload PDF (885K) -
Kazuharu Iwasaki2007 Volume 54 Issue 2 Pages 99-106
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSEffects of doped Mn3+, Co3+ and Al3+ ions in α-FeOOH nanoparticles on the dehydration reaction of α-FeOOH to hematite were investigated by a differential scanning calorimetry analysis. Effect of doped Mn3+ ion on the structure and morphology of α-FeOOH was also investigated.
In α-FeOOH nanoparticles containing Mn, Mn3+ ions were all incorporated into α-FeOOH crystals at Mn/Fe mole ratio; 0 to 0.28, and an acicular shape of particles was maintained after adding Mn3+ ions to α-FeOOH. Dependence of normalized interplanar spacing on Mn contents was also made clear in α-FeOOH particles containing Mn.
Dependences of the differential scanning calorimetry of the dehydration reaction on the rate of heating were clarified in α-FeOOH particles containing Mn, Co and Al. Endothermic reaction was detected in DSC curves. Relationships between peak temperatures of endothermic reaction and the Mn, Co and Al contents were clarified in α-FeOOH particles containing Mn, Co and Al. Peak temperatures increase with increasing cation contents.
In either case of α-FeOOH particles containing Mn, Co and Al, good linear relationships between the rates of heating and the peak temperatures of endothermic reaction were obtained by using Ozawa's method. Dependences of activation energies of dehydration reaction on cation contents were clarified in α-FeOOH particles containing Mn, Co and Al.View full abstractDownload PDF (1395K) -
Keizo Kobayashi, Kimihiro Ozaki, Masashi Mikami, Yukio Ishikawa2007 Volume 54 Issue 2 Pages 107-111
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSSodium chloride powder has been consolidated using pulsed-current sintering method for the substrate. The utilization of the punch made of Ti-2at%Fe-10at%Si alloy has made it possible to produce a sodium chloride compact with a smooth surface and no reactant. Ti-Ni thin film has been prepared on the sodium chloride substrate by sputtering method. Ti-Ni sputtering target has been prepared using pulsed current sintering of the powder mixture of Ti and Ni powders with the composition of Ti-50at%Ni.
The thickness of Ti-Ni film prepared for the sputtering time of 10.8 ks has been about 70μm. The sputtered Ti-Ni film has been spontaneously separated from the sodium chloride substrate in the water. The film has had an amorphous structure and crystallized at 820 K.View full abstractDownload PDF (757K) -
Tarequl Islam Bhuiyan, Makoto Nakanishi, Yoshihiro Kusano, Tatsuo Fuji ...2007 Volume 54 Issue 2 Pages 112-118
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSCerium doped hematite powders obtained by polymeric complex method following the hydrolysis of FeCl3·6H2O and Ce(NH4)2(NO3)6. X-ray diffraction pattern of cerium doped samples obtained at 1000°C∼1200°C for two hours in air revealed some solubility of cerium ion in α-Fe2O3 over the composition range of 5%∼15 at% that were characterized by the shifting of X-ray diffraction peaks compared with the internal silicon standard. X-ray Photoelectron Spectra investigations revealed the existence of Ce3+ ion at higher temperature. Unit cell parameters were found to expand due to the incorporation of cerium ions into the hematite lattice. Field Emission Scanning Electron Microscopy studies showed that the growth of particles was suppressed in the appearance of cerium ions into the α-Fe2O3 lattice. Fe2-xCexO3 exhibits much lower magnetization due to the incorporation of non-magnetic cerium ions into the α-Fe2O3. Spectroscopy measurement evidenced that cerium doped hematite samples exhibited brighter yellowish red color tone than that of pure α-Fe2O3.View full abstractDownload PDF (821K)
Special Issue:Conducting Ceramic Materials
Summarization
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Noboru Ichinose2007 Volume 54 Issue 2 Pages 120
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSDownload PDF (102K)
Paper
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Yuki Orikasa, Naoaki Hayashi, Shigetoshi Muranaka2007 Volume 54 Issue 2 Pages 121-125
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSUsing a Zn3In2O6 target, zinc-indium oxide thin films were prepared by rf magnetron sputtering at different substrate temperatures. The influence of the substrate temperature on the structure, Zn: In ratio, and optical, electrical and thermoelectric properties were studied. C-axis oriented thin films were deposited. The ratio of zinc to indium decreased with increasing the substrate temperature. An average transmittance of about 80% in the visible range was obtained. Conductivity of the films increased with increasing the temperature. The Seebeck coefficient was largest for the films deposited at room temperature. The films deposited at 500°C showed the highest power factor of PF=8.21×10−5 (W/mK2).View full abstractDownload PDF (684K) -
Hiroshi Nanbu, Takahiro Yamada, Hisanori Yamane2007 Volume 54 Issue 2 Pages 126-129
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSEu-doped GaN crystals were synthesized at 600-750°C and N2 pressure of 5 MPa from 1 mol% Eu-added Na-Ga melts. The yield and morphology of crystals varied with temperature and Na mole fraction, rNa=Na/(Na+Ga) in the melts. Colorless transparent columnar crystals of Eu-doped GaN were obtained as crusts formed on the Na-Ga melt surface at rNa=0.67 and 650 or 700°C. Under an ultraviolet light, the crusts glowed red. A strong emission peak concerned with the intra-4f transition of Eu3+ from 5D0 to 7F2 was observed at 621 nm in the photoluminescence (PL) spectrum. The maximum PL intensity was observed in the sample prepared at rNa=0.67 and 650°C.View full abstractDownload PDF (548K) -
Hiroyuki Shimizu, Mitsuaki Morita, Hajime Miyazawa, Haruo Hirose, Kats ...2007 Volume 54 Issue 2 Pages 130-135
Published: 2007
Released on J-STAGE: June 26, 2007
JOURNAL OPEN ACCESSThe authors have reported that superconductive layer can be produced underneath the laser melted layer of press formed bulk of prospective superconductive powder of Bi system. This paper deals with the morphology and mechanical properties of the bulks, which were press formed at pressures between 29 MPa and 196 MPa and treated by laser scan with different powers such as 6, 7 and 8 W. Results showed that (1) the bulk forming pressures adopted in the study give negligible influence on the width of the groove the laser scanning caused while the laser scan results in the grooves with width from 2.3 to 3.4 mm, (2) the laser scan on the surface of the bulk produces groove with depth from 0.71 to 0.18 mm with the increasing power, (3) the resultant thickness of the melted layer is in the range between 600 and 900 μm, and that of the superconductive layer is in the range between 50 and 120 μm, (4) the bulk forming pressure affects surface roughness of the treated region in such a way that with increasing pressure the surface roughness increases in the value from 5.2 to 7.3 μmRa although the laser output power gives small effects on the value, (5) the hardness measurement shows the highest value 120 Hv was obtained for the superconductive layer, 100 Hv for the melted layer and 45 Hv for the body as press formed, (6) the laser treatment causes the fracture strength to effectively change the value from 15 (before treatment) to 34 N (after treatment).View full abstractDownload PDF (897K)
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