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Volume 56, Issue 4
April
Displaying 1-9 of 9 articles from this issue
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Paper
Paper
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YoungJoon An, Ken Nishida, Takashi Yamamoto, Shunkichi Ueda, Takeshi D ...2009 Volume 56 Issue 4 Pages 149-155
Published: 2009
Released on J-STAGE: May 19, 2009
JOURNAL OPEN ACCESSRecently, modern technologies of wireless communication have shown rapid progress, and because of these various applications in high frequencies there is a concern about effects on other electronic device and unexpected malfunctions. For these reasons, a microwave absorber in free space has become necessary for a safe electromagnetic wave environment.
In this report, we explain characteristic evaluations of a microwave absorber which is used in an electronic toll collection (ETC) device, fabricated by a composite of magnetic (Fe) and dielectric (TiO2) materials. It was evaluated by free-space method with horn antennas using a transverse electric wave, a transverse magnetic wave and a circularly polarized wave. The reflection loss in free space is -20 dB or more around a central frequency of 5.8 GHz at oblique-incident angles of up to 60°, which satisfy the necessary condition for ETC use in Japan, and using arrangement and changing structure, it also satisfies necessary condition for ETC use without a characteristic deterioration. In addition, we compare experimental results with calculation results of transmission line theory as well as EEM-FDM simulation results.View full abstractDownload PDF (1318K) -
Satoshi Sunada, Takuo Yamada, Shigeo Tanaka, Norio Nunomura, Kazuhiko ...2009 Volume 56 Issue 4 Pages 156-166
Published: 2009
Released on J-STAGE: May 19, 2009
JOURNAL OPEN ACCESSMetal injection molding (MIM), one of the powder metallurgy processes, has attracted considerable interest because of the advantage of better formability to fabricate complex shape products without machining and welding. In this experiment, the specimens prepared by the conventional MIM process and the powder space holder-metal injection molding process (PSH-MIM process) were used, and their corrosion behaviors were investigated through the electrochemical procedures such as potendiodynamic polarization curve measurement, electrochemical impedance spectroscopy (EIS) and the coulostat method. The porous specimen prepared by PSH-MIM process was corroded more easily than the one prepared by the conventional MIM process. This is because the PSH-MIM specimen has the greater surface area than the conventional specimen. The EIS and the coulostat measurement methods were confirmed to be quite effective for the measurement of corrosion behavior of the porous materials.View full abstractDownload PDF (1334K)
Special Issue: Developmen of Novel Materials through "Chemical Tectonics"
Summarization
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Chikara Ohtsuki2009 Volume 56 Issue 4 Pages 168
Published: 2009
Released on J-STAGE: May 19, 2009
JOURNAL OPEN ACCESSDownload PDF (145K)
Review
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Kohmei Halada2009 Volume 56 Issue 4 Pages 169-176
Published: 2009
Released on J-STAGE: May 19, 2009
JOURNAL OPEN ACCESSA new approach to materials' innovation of substitution of rare elements by common elements is discussed. The importance of the innovation of substitution is insisted from the viewpoint of increasing materials' supply risk. A national project named "Elements Science & Technology" is mentioned to start efforts to sustainable use of resources. While "reduce", "recycle", "substitution" and "restriction" are keywords in the project, fundamental substitution is expected with great interest. For the fundamental substitution, a new concept named "Lattice Engineering" is introduced. Family concepts of lattice engineering, namely, meta-metallurgy, instructed inter-atom infrastructure and nano-alchemy are also introduced.View full abstractDownload PDF (1782K) -
So Baba, Jun Akedo2009 Volume 56 Issue 4 Pages 177-182
Published: 2009
Released on J-STAGE: May 19, 2009
JOURNAL OPEN ACCESSLaser annealing has been conventionally used for surface treatment, sintering of structural materials and crystallization of amorphous materials. This article describes the possibility to apply laser annealing for electronic ceramics. Pb(Zr, Ti)O3 (PZT) films with a thickness of over 10 μm directly deposited onto stainless-steel substrates (PZT/SUS) by aerosol deposition (AD) technique have been annealed by infrared laser irradiation in order to improve their ferroelectric and/or piezoelectric properties. The metallic luster of the stainless-steel substrate has been retained after laser heating. The remanent polarization (Pr) and coercive field (Ec) values of the films annealed by laser irradiation was Pr > 40 μC/cm2 and Ec < 40 kV/cm, respectively, being superior to those of the PZT/SUS annealed by electric furnace. The area of grain growth for the irradiated PZT films coincides with the fascicle spot size. In contrast, in the case of bulk PZT, infrared laser irradiation with the same spot size is causing grain growth on a larger area (20 times the spot diameter). The combination of laser annealing and AD technique is attractive not only for production of electronic ceramics devices but also to confirm to heat treatment of electronic ceramics to the desired areas.View full abstractDownload PDF (1507K)
Paper
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Koichiro Ueda, Koji Tomita, Kazumi Fujita, Masato Kakihana, Shinya Saw ...2009 Volume 56 Issue 4 Pages 183-187
Published: 2009
Released on J-STAGE: May 19, 2009
JOURNAL OPEN ACCESSBa2Ti9O20 has a similar structure to Hollandite structure, and has high ionic conductivity because of its tunnel structure. It is used as electronic material in high frequency devices due to its ferroelectricity and the small temperature coefficient. The single phase of Ba2Ti9O20 is hard to obtain because only the small deviations from the required stoichiometry lead to formation of impurity phases having close chemical composition. In this study we prepared precursor of Ba2Ti9O20 by complex gellation method in which citratoperoxititanic acid tetranuclear complex was used as a Ti source. The homogeneous precursor was obtained by mixing the Ti complex, Ba(CH3COO)2, and H3BO3 (as a flux) in aqueous solution. The obtained precursor was then heat-treated at 1,273 K, which is 230 K below the temperature needed for the conventional solid-state reaction method, and the single phase of Ba2Ti9O20 was formed. The crystallite size of the prepared powder was less than 100 nm that is desirable for ferroelectric materials.View full abstractDownload PDF (916K) -
Masato Kakihana, Makoto Kobayashi, Valery Petrykin, Koji Tomita2009 Volume 56 Issue 4 Pages 188-193
Published: 2009
Released on J-STAGE: May 19, 2009
JOURNAL OPEN ACCESSA panel of new stable and water soluble complexes of titanium (IV) with natural hydroxy-carboxylic acids such as citric, tartaric, lactic or glycolic acid as ligands was developed. A typical structure of these complex ions includes a peroxo-group, and a hydroxy-carboxylic acid molecule attached to the metal ion by carboxylic and hydroxylic groups to form stable species. The tight coordination and negative charge of complex ions are responsible for stability of these new compounds in water solutions in a wide range of temperatures and pH. Use of natural non-toxic ligands and ammonium as counterions make such titanium compounds convenient reagents for "green" synthesis of titanium containing materials by aqueous solution methods.
The architecture of titanium complexes includes structural motifs of different polymorphic forms of TiO2, which allows for application of these compounds as building blocks (tecton) for synthesis of titania with different crystal structures by a simple hydrothermal processes. In this way anatase, rutile, TiO2(B) and brookite were prepared in a reproducible and highly selective way. For the first time TiO2(B) and brookite were synthesized as single phase nano-crystals by a "one-pot" hydrothermal process, and their outstanding photo-catalytic activities were revealed.View full abstractDownload PDF (995K) -
Naoya Enomoto, Kosuke Yamada, Feng Dang, Miki Inada, Junichi Hojo2009 Volume 56 Issue 4 Pages 194-198
Published: 2009
Released on J-STAGE: May 19, 2009
JOURNAL OPEN ACCESSMagnetite nanoparticles were synthesized by oxidizing a Fe(OH)2 precipitate in various ultrasonic (US) fields including traveling wave (TW; 20 kHz) driven by a horn-type homogenizer and standing waves (SW; 45, 100, 200 kHz) driven by a cleaner-type sonicator. Compared to a process with mechanical stirring (MS), each of US treatment completed the magnetite formation in much shorter time. The size of the nanoparticles decreased with the decreasing initial [Fe2+] concentration. Noticeably at [Fe2+]=0.001 mol/L, no more particles but brown amorphous sols were formed in either MS or TW process. To the contrary, black magnetite nanoparticles were formed in the SW process as usual as higher concentration. The SW ultrasonication enabled to gather cavitation bubbles in its nodes, and then it is inferred that high supersaturation enough to form nanoparticles were achieved locally in the nodes of the SW field.View full abstractDownload PDF (755K)
Review
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Chikara Ohtsuki, Toshiki Miyazaki2009 Volume 56 Issue 4 Pages 199-204
Published: 2009
Released on J-STAGE: May 19, 2009
JOURNAL OPEN ACCESSSo-called bioactive ceramics exhibit specific biological affinity, i.e. direct bonding to surrounding bone, when implanted in bony defects. However, there is limitation on clinical applications, because of their inappropriate mechanical properties such as low fracture toughness and high elastic modulus. Novel bioactive materials exhibiting high flexibility have been desired. The essential prerequisite for artificial materials to exhibit bioactivity is deposition of bone-like apatite on their surfaces in body environment. This apatite deposition is governed not only by the dissolution of the materials but also by heterogeneous nucleation on the materials surface, followed by crystal growth by consuming calcium and phosphate ions from surrounding body fluid. These findings bring us an idea that bioactive organic-inorganic hybrids with high flexibility can be developed by control in direction and amounts of transformed chemical species. So, the control in chemicovectors on bioactive materials provides attractive design of bone-bonding materials with various functionalities. In this paper, we review development of organic-inorganic hybrids from hydroxyethylmethacrylate (HEMA), starch and collagen-like polypeptide, on the view points of chemicovector.View full abstractDownload PDF (1060K)
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