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Sugita, Tsuyoshi; Yoshida, Hirokazu*; Kodama, Hiroto*; Ishigaki, Toru*; Oba, Yojiro*
Journal of the Ceramic Society of Japan, 132(9), p.548 - 554, 2024/09
Times Cited Count：1 Percentile：36.65(Materials Science, Ceramics)Porosity plays an essential role in the performance of ceramics. In this study, the effects of clay composition and firing temperature on the pore size distribution of ceramics were evaluated by small-angle neutron scattering (SANS) measurements. Compared with quartz-rich pure Kasama clay, a mullite-rich Kasama clay blend had smaller pores after heat treatment. SANS measurements of D
O-absorbed samples revealed that open pores with sizes ranging from tens of nanometers to about a micrometer contributed to the absorption of water. The closed and open pores coarsened and the total porosity decreased with increasing firing temperature.
O-2SiO, NaO-2SiO and KO-2SiOKawaguchi, Munemichi; Uno, Masayoshi*
Journal of the Ceramic Society of Japan, 128(10), p.832 - 838, 2020/10
Times Cited Count：3 Percentile：12.68(Materials Science, Ceramics)This study developed phase-field method (PFM) technique in oxide melt system by using a new mobility coefficient (
). The crystal growth rates (
) obtained by the PFM calculation with the constant were comparable to the thermodynamic driving force in normal growth model. The temperature dependence of the was determined from the experimental crystal growth rates and the . Using the determined , the crystal growth rates (
) in alkali disilicate glasses, LiO-2SiO, NaO-2SiO and KO-2SiO were simulated. The temperature dependence of the was qualitatively and quantitatively so similar that the PFM calculation results demonstrated the validity of the . Especially, the obtained by the PFM calculation appeared the rapid increase just below the thermodynamic melting point (
) and the steep peak at around -100 K. Additionally, as the temperature decreased, the apparently approached zero ms
, which is limited by the representing the interface jump process. Furthermore, we implemented the PFM calculation for the variation of the parameter 
in the . As the increased from zero to two, the peak of the became steeper and the peak temperature of the shifted to the high temperature side. The parameters 
and in the increased exponentially and decreased linearly as the atomic number of the alkali metal increased due to the ionic potential, respectively. This calculation revealed that the and in the were close and reasonable for each other.
Utsumi, Taro*; Terasawa, Toshiharu*; Kudo, Isamu*; Suzuki, Tsuneo*; Nakayama, Tadachika*; Suematsu, Hisayuki*; Ogawa, Toru
Journal of the Ceramic Society of Japan, 128(2), p.96 - 100, 2020/02
Times Cited Count：5 Percentile：21.60(Materials Science, Ceramics)A method to control the millimeter-sized open porosity in geopolymer foam was attempted to produce hydrogen recombining supports for radioactive waste canisters. The raw materials were mixed with silicon powder as a foaming agent. Geopolymer foams with open porosities as high as 81% were obtained by a water bath treatment before pouring the slurry into the mold. The increase in the open porosity of geopolymer foam was observed by an increase in the water bath treatment time. It was thought that the viscosity of slurry increase induced the pores trapped inside the geopolymer foam and connected to form millimeter-sized and open pores. It was concluded that a simple method with a foaming agent and a water bath treatment to prepare geopolymer foams with high open porosity was developed.
addition on water durability of FeO-FeO
-PO
glassesKitamura, Naoto*; Nomura, Akira*; Saito, Akira*; Kobayashi, Hidekazu; Amamoto, Ippei; Takebe, Hiromichi*
Journal of the Ceramic Society of Japan, 126(11), p.948 - 951, 2018/11
Times Cited Count：6 Percentile：23.43(Materials Science, Ceramics)We studied compositional dependence of water durability of Zr(IV) containing FeO-FeO-PO glasses systems, which can apply to immobilize nuclear waste of Zr isotope. Stabilized film with interference fringe on the surface improves better water durability after immersion tests for BaO and ZrO coexisting glasses without fracture. On the other hand, microcrystalline ZrPO
was detected in the glass matrix when more than 1 mol% of ZrO incorporated. The effect of impregnated ZrPO crystal on the structure was discussed based on the phosphate structure analyzed by Raman spectra. Formation of Q
and Q
units, which contribute to water durability in the glass, are due to preferential precipitation of ZrPO crystal.
Narisawa, Masaki*; Koka, Masashi; Takeyama, Akinori; Sugimoto, Masaki; Idesaki, Akira; Sato, Takahiro; Hokazono, Hiroki*; Kawai, Taketoshi*; Iwase, Akihiro*
Journal of the Ceramic Society of Japan, 123(9), p.805 - 808, 2015/09
Maeda, Hiroki*; Ishiguro, Yuki*; Honda, Takashi*; Jung, J.-S.*; Michimura, Shinji*; Inami, Toshiya; Kimura, Tsuyoshi*; Wakabayashi, Yusuke*
Journal of the Ceramic Society of Japan, 121(3), p.265 - 267, 2013/03
Times Cited Count：6 Percentile：33.24(Materials Science, Ceramics)Structural deformation of a magnetocapacitive material SmMnO was studied by X-ray diffraction measurement in a magnetic field. This antiferromagnetic material shows a jump in dielectric constant at 9 K only when a magnetic field of a few tesla is applied. In-field X-ray diffraction measurements clarified that there is no sudden change in structure that involves atomic displacement within the c-plane in Pbnm notation, while the antiferromagnetic phase transition at 60 K gives rise to a noticeable rotation of the MnO
octahedra. This rotation occurs to maximize the energy gain through the exchange interaction.
Mannan, M. A.*; Kida, Tetsuya*; Noguchi, Hideyuki*; Nagano, Masamitsu*; Shimoyama, Iwao; Hirao, Norie; Baba, Yuji
Journal of the Ceramic Society of Japan, 117(1364), p.503 - 507, 2009/04
Times Cited Count：12 Percentile：55.04(Materials Science, Ceramics)Oriented hexagonal BCN films were synthesized on Si(100) substrate by radiofrequency plasma enhanced chemical vapor deposition using tris-(dimethylamino)borane as a precursor. The formation of the crystalline hexagonal BCN hybrids was confirmed by FT-IR and XRD. CH
+ H carrier gas increased the C content in the films in comparison with N carrier gas. XPS measurement showed that the films were composed of a variety of B-N, B-C, C-N bonds to form the BCN atomic hybrids. The 
resonance peak in the B K-edge NEXAFS spectra also indicated the presence of the 
hybrid configuration of B-C-N bonds like BN in h-BN. The 
resonance peaks suggested the diversity in the bonds in the films. Orientation of the h-BCN hybrids was suggested on the basis of the polarization dependence of NEXAFS.
Nagata, Hidezumi*; Hirao, Norie*; Onoki, Takamasa*; Baba, Yuji; Yamasaki, Yuki*; Nakahira, Atsushi*
Journal of the Ceramic Society of Japan, 116(1350), p.216 - 219, 2008/02
Times Cited Count：10 Percentile：51.50(Materials Science, Ceramics)Bulky palladium catalyst supported on mesoporous silica (Pd-MCM-41) was successfully synthesized by hydrothermal hot-pressing method. The structure of the palladium species in Pd-MCM-41 bulk before and after heat-treatment process was investigated by X-ray diffraction (XRD), X-ray absorption near edge structure (XANES) and transmission electron microscopy (TEM). On the basis of these results, the microstructures and mesoporous properties of Pd-MCM-41 were discussed. As a result, it was revealed that the obtained Pd-MCM-41 bulks possessed a high area of over 1000 m
/g and the electronic state of palladium in Pd-MCM-41 bulk is almost equal to palladium (0) metal.
BC and recovery by annealingDonomae, Takako; Tachi, Yoshiaki; Sekine, Manabu*; Morohashi, Yuko; Akasaka, Naoaki; Onose, Shoji
Journal of the Ceramic Society of Japan, 115(1345), p.551 - 555, 2007/09
Times Cited Count：4 Percentile：28.22(Materials Science, Ceramics)Use of moderator materials in Fast Breeder Reactor (FBR) is effective for transmutation technology, and BC is one of the candidates. Up to now, the behavior of 
BC as the Control rod material is well known, but that of BC is hardly investigated. In this paper, the radiation effects of BC pellets, neutron irradiated in the experimental fast reactor JOYO were studied. From the experimental results, it was observed that no macro-cracks were recognized in the irradiated BC pellets. But, bubble nucleation was found in grain and along grain boundaries of BC. And, it was shown that the conductivity of BC was higher than that of BC. During the annealing from room temperature to 1400
C, three recovery stages were found on thermal conductivity. It was suggested that, the recovery of BC was related to the dispersion behavior of helium. Judging from these results, as BC was mechanically more stable compared with BC under irradiation, it was shown that BC had high applicability for a moderator.
Ishiyama, Shintaro; Maruyama, Shigeki*
Journal of the Ceramic Society of Japan, Supplement, Vol.112, No.1 (CD-ROM), p.S159 - S166, 2004/05
no abstracts in English
Li-enriched LiTiO pebbles by wet processTsuchiya, Kunihiko; Hoshino, Tsuyoshi; Kawamura, Hiroshi; Takayama, Tomoo*
Journal of the Ceramic Society of Japan, Supplement, Vol.112, No.1 (CD-ROM), p.S183 - S186, 2004/05
no abstracts in English
TiOHoshino, Tsuyoshi; Kobayashi, Takeshi*; Nashimoto, Makoto*; Kawamura, Hiroshi; Terai, Takayuki*; Yamawaki, Michio*; Takahashi, Yoichi*
Journal of the Ceramic Society of Japan, Supplement, Vol.112, No.1 (CD-ROM), p.S354 - S357, 2004/05
no abstracts in English
C-carbon fiber composite ceramics as plasma facing materials in nuclear fusion reactor, 3; Heat resistance evaluation by electron beam irradiation and by in situ plasma discharge in JT-60Jimbo, Ryutaro*; Saido, Masahiro; Nakamura, Kazuyuki; Akiba, Masato; ; Dairaku, Masayuki; ; ; ;
Journal of the Ceramic Society of Japan, International Edition, 105, p.1179 - 1187, 1997/00
no abstracts in English
Kawamura, Hiroshi; ; ; ;
Journal of the Ceramic Society of Japan, International Edition, 97, p.1403 - 1408, 1989/00
no abstracts in English
