Journal of the Ceramic Society of Japan
Online ISSN : 1348-6535
Print ISSN : 1882-0743
ISSN-L : 1348-6535
Volume 119, Issue 1388
(April)
Displaying 1-15 of 15 articles from this issue
Special Articles: The 64th CerSJ Awards for Advancements in Ceramic Science and Technology: Review
  • Toru WAKIHARA
    2011 Volume 119 Issue 1388 Pages 255-260
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    Zeolites have been utilized widely in industry and in household products, for example, as adsorbents, ion-exchangers and catalysts, and have attracted considerable attention as host materials for various recent nanotechnology applications. The SiAlON ceramics, of which α-SiAlON and β-SiAlON are representative phases, are useful for engineering applications because of their excellent mechanical and chemical properties. This review introduces the author’s contributions to the synthesis and characterization of these Si-based materials.
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  • Tomoaki YAMADA
    2011 Volume 119 Issue 1388 Pages 261-265
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    Using ultra-thin TiN sacrificial template, the epitaxial (Ba,Sr)TiO3 [BST] films on c-Al2O3 were grown by pulsed laser deposition. TiN epitaxially grew on c-Al2O3 with (111) orientation, which promoted the (111) epitaxial growth of upper BST films. The obtained epitaxial BST films showed significantly larger dielectric constant compared with polycrystalline films directly deposited on c-Al2O3 over the wide temperature range. By inserting the TiN template, the temperature corresponding to maximum dielectric constant of BST films was shifted up by 50 K, which is mainly due to the in-plane tensile strain induced by the difference in thermal expansion coefficients of BST and c-Al2O3.
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  • Masanobu KAMITAKAHARA
    2011 Volume 119 Issue 1388 Pages 266-270
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    Ceramics can not only be used to create tools for use in our daily life but also can contribute to the health of our body. As ceramics composed of calcium phosphates show a high biological affinity to bone tissue, they have been used for the repair and regeneration of bone. Although conventional sintered hydroxyapatite (HA) ceramics and tricalcium phosphate (TCP) ceramics are both widely used, the ability of these materials to regenerate the bone is insufficient and their use remains limited. As calcium phosphate is an inorganic component of bone, highly functional artificial bones could be obtained if we made best use of the properties of calcium phosphates. This paper describes methods to improve the functionality of artificial bones based on calcium phosphates.
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Papers
  • Eiji FUCHITA, Eiji TOKIZAKI, Eiichi OZAWA, Yoshio SAKKA
    2011 Volume 119 Issue 1388 Pages 271-276
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    The aerosol gas deposition method (AGD) is a low-temperature method. No heating occurs during the AGD process when forming the AGD films. Nevertheless, ceramic films can be synthesized at room temperature directly from the source ceramic powders. In this paper, we report that the high-temperature phase of zirconia was found in zirconia films synthesized by AGD and that a light emission phenomenon was observed at the deposition site. The generation of the high-temperature phase was dependent on the mean diameter of the source ceramic powders. Both a small powder of less than two or three microns in diameter and large powder particles of more than 10 microns in diameter have the low possibility of generating the high-temperature phase when compared to that of 7-micron diameter powder. The appearance of the high-temperature phase and the light emission might be related to the formation mechanism of the AGD film at ambient temperature.
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  • Ryo SASAI, Yukitaka MATSUMOTO, Takeshi ITAKURA
    2011 Volume 119 Issue 1388 Pages 277-281
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    To develop a practical method of treating boron-containing wastewater, we custom designed two laboratory-scale continuous-flow-type hydrothermal mineralization apparatuses. We carried out a hydrothermal treatment using a continuous-flow apparatus, using Ca(OH)2, CaCl2, and both Ca(OH)2 and CaCl2 as mineralizers, under various pH conditions. Our results show that using CaCl2 under optimal pH conditions (pH = approximately 12) allowed for the stable removal of boron from wastewater. One of the precipitates obtained in this process was parasibirskite, which is a natural boron mineral. Finally, because the residual concentration of boron could not be reduced below 10 mg/dm3, we propose a realistic boron removal wastewater treatment system incorporating the hydrothermal mineralization method.
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  • Atsushi FURUBAYASHI, Toshio KIMURA
    2011 Volume 119 Issue 1388 Pages 282-284
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    Needlelike Sr0.5Ba0.5Nb2O6 powder particles were prepared from SrCO3, BaCO3, and Nb2O5 in the presence of a mixture of molten SrCl2 and BaCl2. When the composition of the mixture of oxide and carbonate was fixed to be SrCO3:BaCO3:Nb2O5 = 1:1:2, the phase and morphology of the product particles were dependent on the composition of molten salt. The exchange reaction, BaO + SrCl2 = BaCl2 + SrO, enriched Sr in the oxide phase. The relation between the compositions of the salt mixture and the reaction product was determined, and needlelike Sr0.5Ba0.5Nb2O6 particles were obtained by using the molten salt containing 18 mol % SrCl2.
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  • Yoshinori KOBAYASHI, Etsushi ODA, Takeshi NISHIUCHI, Takashi NAKAGAWA
    2011 Volume 119 Issue 1388 Pages 285-290
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    The occupation sites of lanthanum and cobalt ions in the La–Co substituted M type ferrite Sr1−xLaxCoxFe11.6−xO19, where x = 0.20 to 0.35, were analyzed by the neutron diffraction, the extended X-ray absorption fine structure (EXAFS) and the X-ray magnetic circular dichroism (XMCD) in order to understand the relationship between the local structure and the improvements of magnetic characteristics in the La–Co substituted M-type ferrite. The results of EXAFS analysis suggest that Co is partitioned in the 4f1, 2a and 12k sites, which is in a good agreement with the results of the neutron diffraction analysis. XMCD measurements also indicate that the ferric ions at the tetrahedral site 4f1 is replaced by elements of a smaller magnetic moment.
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  • Ryota KOBAYASHI, Yoshiaki MORIYA, Makoto IMAMURA, Kazuhiro OOSAWA, Kat ...
    2011 Volume 119 Issue 1388 Pages 291-294
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    Aluminum nitride (AlN) ceramics were fabricated by pressureless sintering with various sintering additives such as 5 mass % Y2O3, 2 mass % Y2O3–3 mass % Al2O3, 3 mass % Y2O3–1 mass % CaO–0.08 mass % B, and 6 mass % Y2O3–2 mass % CaO–0.16 mass % B. The relative density, phases present, lattice parameter c, and thermal conductivity of the samples were evaluated. The oxygen concentration in AlN lattice was estimated from the lattice parameter c by using the relation between the oxygen concentration and the lattice parameter c of AlN. To analyze the effects on the thermal conductivity of the samples, we plotted the oxygen concentration in AlN lattice estimated from the lattice parameters c versus the thermal resistivity, which is inverse of the thermal conductivity measured in this work. The data of the samples sintered with 5 mass % Y2O3 and 3 mass % Y2O3–1 mass % CaO–0.08 mass % B located on the plot of the relation between oxygen concentration in AlN lattice and thermal resistivity of AlN presented by Slack (Slack’s line) or Harris et al. (Harris’s line), respectively. In contrast, the data of the samples sintered with 2 mass % Y2O3–3 mass % Al2O3 and 6 mass % Y2O3–2 mass % CaO–0.16 mass % B, which contain excess grain boundary phases, located above the Harris’s line. It was suggested that the thermal conductivity of the samples could be influenced by the density, the oxygen content in AlN lattice, and the presence of grain boundary phases.
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  • Kazuki TAJIMA, Hiromi HOTTA, Yasusei YAMADA, Masahisa OKADA, Kazuki YO ...
    2011 Volume 119 Issue 1388 Pages 295-302
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    We have been engaged in research and development of an electrochromic switchable mirror with a multilayer structure of Mg4Ni/Pd/Al/Ta2O5/HXWO3/indium tin oxide (ITO) on a glass substrate. In our recent work, an as-prepared device was found to be easily degraded by environmental factors such as temperature and humidity, as shown by a degraded surface of the device. In this work, a polyvinyl chloride (PVC) layer was fabricated as a sealant layer for improving the environmental durability of the device. The structure of the layer could be controlled by adjusting the fabrication conditions such as the concentration of materials and rotational speed used in spin coating. The optical switching properties of the device with the sealant layer were also investigated. The sealant layer was fabricated using 1.25 wt % PVC solution in tetrahydrofuran at a rotational speed of 500 rpm. Although the device with the sealant layer had a thicker film, it showed superior optical switching properties even with a change in reflectance range due to multilayer interference. Furthermore, the device without the sealant layer easily degraded in an accelerated degradation test at a constant temperature of 40°C and a constant relative humidity of 80% after only 2 days. On the other hand, the surface of the device with the sealant layer showed no change in the same test. This result suggests that the PVC sealant layer has some advantages for preventing the environmental effects on the properties of the device.
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  • Kimitoshi SATO, Masashi IKEDA, Ji-Guang LI, Hidehiro KAMIYA, Takamasa ...
    2011 Volume 119 Issue 1388 Pages 303-306
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    Spherical TiO2 nanoparticles, with mean primary particle sizes of 29 and 53 nm, were synthesized by Ar/O2 radio frequency (RF) induction thermal plasma pyrolysis of atomized liquid precursors containing titanium tetrabutoxide. In the synthesis of the 29-nm-sized TiO2 nanopowders, the counter-flow gas was injected against plasma from the bottom of the reactor in order to enhance the quench rate. The plasma-synthesized nanoparticles at 1.0 vol % in solid fraction were dispersed by ultrasonic irradiation in the aqueous solution of polyacrylic acid with an average molecular weight of 8000. The mean aggregate size of the plasma-synthesized powders in aqueous suspension measured by a particle size analyzer corresponded exactly to the mean primary particle size evaluated by examining surface area data and by analyzing scanning electron microscopy (SEM) images, which suggests that the plasma-synthesized TiO2 nanoparticles were individually dispersed in water.
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  • Masashi YOSHINAGA, Haruo KISHIMOTO, Manuel E. BRITO, Katsuhiko YAMAJI, ...
    2011 Volume 119 Issue 1388 Pages 307-309
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    Distribution maps of carbon deposited on nickel particles were obtained by micro-Raman spectroscopy. Nickel film was prepared on the oxide substrates of yttria stabilized zirconia (YSZ) and gadolinia doped ceria (GDC). Carbon deposition was induced by annealing in dry methane for 10 min at both 863 and 933 K. Morphology of nickel film was changed into particles with the size of several ten-nanometer to several micrometer at the edge of the nickel film after annealing. For the nickel/YSZ systems, carbon thoroughly deposited on all of sintered nickel particles but was not observed on YSZ surface. For the nickel/GDC systems, carbon was deposited only on the nickel particles with sub-micrometer size.
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  • Yu YOU, Akihiko ITO, Rong TU, Takashi GOTO
    2011 Volume 119 Issue 1388 Pages 310-313
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    TiN films were prepared on Ti(C,N)-based cermet substrate by laser chemical vapor deposition using titanium isopropoxide dipivaloylmethane [Ti(OiPr)2(dpm)2] and ammonia (NH3) as precursors. The effects of deposition temperature (Tdep) and laser power (PL) on the crystal phase, microstructure and adhesion were investigated. TiN film was prepared at Tdep > 903 K (PL > 100 W). The microstructure of TiN film changed from rose-like grains to pyramid-like grains to aggregate grains with increasing PL and Tdep. Highly adhesive film was obtained at moderate Tdep = 1047 K (PL = 120 W).
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  • Wenbin DAI, Xinli WANG, Peng ZHAO, Lin ZHAO, Jingkun YU
    2011 Volume 119 Issue 1388 Pages 314-318
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    The microstructure of 1 mol % calcia-doped yttria under different sintering condition was investigated, and the thermal shock resistance of yttria with and without additive was compared in present work. The results showed that by adding 1 mol % calcia, the sinterability of yttria is greatly improved and the sample can be sintered as low as 1300°C. Increasing heating temperature and prolonging soaking time are beneficial to form coarse grains with lots of closed pores in calcia-added sample at temperatures higher than 1500°C. By theoretical analysis, it is known that because of the solid solution of Ca2+, defects are generated in the yttria lattice, and the activation energy for diffusion is decreased. Therefore, the grain boundary mobility of yttria is accelerated and closed pores are left inside coarse grains when pores cannot move with yttria grain boundaries anymore. The water quench test reveals that the non-additive sample heated at 1500°C has the highest thermal shock resistance and it cannot be utilized under high temperature in industry. On the contrary, the calcia-doped sample has superior thermal shock resistance by the effect of closed pores, and it might be utilized to melt and cast high purity titanium and its alloys through vacuum induction melting (VIM) process.
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Technical report
  • Jung-Hye EOM, Young-Wook KIM, Doo-Hoa JEONG, Seung-Seok LEE
    2011 Volume 119 Issue 1388 Pages 319-321
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    High strength vermiculite–ceramic composites with a layered structure were fabricated by adding cellulose fibers as a pore former and by simple uniaxial pressing and subsequent sintering. During uniaxial pressing, the cellulose fibers were aligned perpendicular to the pressing direction and formed an aligned pore structure during sintering. The thermal conductivity (0.81 W/m·K) and compressive strength (39 MPa) of the composite fabricated from 35 mass % vermiculate, 30 mass % SiO2, 10 mass % Al2O3 and 25 mass % cellulose fibers, measured perpendicular to the pressing direction, were higher than those (0.52 W/m·K and 28 MPa) measured parallel to the pressing direction. The anisotropy in both thermal conductivity and compressive strength was attributed to the microstructural anisotropy.
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Note
  • Naoki KONDO, Hideki HYUGA, Mikinori HOTTA, Hideki KITA
    2011 Volume 119 Issue 1388 Pages 322-324
    Published: April 01, 2011
    Released on J-STAGE: April 01, 2011
    JOURNAL FREE ACCESS
    Silicon nitride was joined using a silicon nitride powder insert of the same composition as the bulk. The joining was performed at 1600°C for 30 min under a mechanical pressure of 13 MPa. The powder insert was densified to form a joint, but grains in the joint were small and equiaxed. As-joined specimens exhibited an average strength of 859 MPa. During heat treatment at 1800°C for 8 h, grain growth occurred, forming a microstructure with rod-like grains in the joint. The semi-homogeneous joint of the same composition and the similar microstructure consisting of rod-like grains to the bulk was successfully obtained. The average strength of the joined specimen was 947 MPa, which was nearly the same to that of the bulk silicon nitride.
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