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Volume 51, Issue 2
Displaying 1-9 of 9 articles from this issue
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Kaduichi Kitagawa, Takeshi Toyoda, Kazuo Kitagawa, Takashi Yamamoto2004 Volume 51 Issue 2 Pages 65-70
Published: February 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe pseudo-ternary solid solution system PbZrO3-PbTiO3-Pb(Mn1/3Sb2/3)O3(PZ-PT-PMS) piezoelectric ceramics were synthesized. However, the value of tolerance factor with Pb(Mn1/3Sb2/3)O3 was nearly 1, Pb(Mn1/3Sb2/3)O3 does not exist itself as a single phase perovskite structure. Pb2Sb2O7 and Pb2MnO4 coexisted. But the small amount of PMS added PZ-PT-PMS showed a single phase perovskite structure. The piezoelectric properties were significantly changed near morphotropic phase boundary (MPB). Small amount of Mn2O3 addition to PZ-PT-PMS improved electromechanical coupling factor (kp) and mechanical quality factor (Qm). The four point bending strength of PZ-PT-PMS was 81.7MPa. And the value of Weibull modulus was 9.0.View full abstractDownload PDF (1845K) -
Hideki Tanaka, Masato Kurihara, Satoshi Maruyama, Tatsuya Osawa, Yusuk ...2004 Volume 51 Issue 2 Pages 71-80
Published: February 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMesocarbon microbeads (MCMB) powders, a kind of synthesized graphite powder, are treated in induction thermal plasmas of high temperature exceeding 10, 000 K and various reactive atmospheres. The plasma-treated powders are compared with mechanical-milled powders in a ball mill. The plasma-treatment and the mechanical-milling do not give rise to the further graphitization. The surface morphology of plasma-treated powders varies depending on plasma treatment atmospheres. The crystallinity difference in the surface region is revealed by Raman spectroscopy. Electrochemical measurements as anode for lithium-ion rechargeable battery are performed in non-aqueous solvents containing 1 M LiClO4. Discharge capacity of the plasma-treated powders is larger than that of original MCMB powder. Especially, the first discharge/charge efficiency of the MCMB powders treated in the atmosphere containing CO2 is higher than that of original MCMB powder. The mechanical-milled powder with the same surface area as plasma-treated powder possesses the lowered first discharge/charge efficiency and discharge capacity. The thermal decomposition reaction of lithiated graphite anodes is also investigated by differential scanning calorimetry (DSC). In DSC, the heat generation, which is associated with the formation of solid electrolyte interphase (SEI), depends on surface area of MCMB powders.View full abstractDownload PDF (4438K) -
Masakuni Ozawa2004 Volume 51 Issue 2 Pages 81-85
Published: February 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe forming and thermal stability of a coat layer was investigated through a simple suspension-dipping procedure of aqueous La-modified γ-Al2O3 suspension. The effect of La on the stabilization of surface area for powder, and the morphology of coat layers, which are heated at elevated temperatures, were examined by X-ray diffraction, nitrogen adsorption and scanning electron microscopy. The La-addition stabilized the metastable phases of Al2O3 at temperatures up to 1200'C, and induced the increase of phase-transformation temperature to α-Al2O3. The surface area of pure Al2O3 layer decreased after heat treatment at 900-1200°C. Several factors for controlling the formation of a coat layer from La-modified γ-Al2O3 suspension were discussed. A fabricated La-modified alumina layer was stable to realize high surface area as well as homogeneous shape without large cracks after heat treatment under heating condition at 1100°C in air.View full abstractDownload PDF (2054K) -
Masakuni Ozawa2004 Volume 51 Issue 2 Pages 86-90
Published: February 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe solid state reaction of composite powders in the system of cobalt-lanthanum-alumina (CoOx-LaOx-Al2O3) was studied for the purpose of the high temperature application of ceramic catalytic device for removing lean-burn nitrogen oxides (NOx) emission. La-modification was effective to the inhibition of the surface-area decrease of a catalyst, however NOx removal activity of pure CoOx-Al2O3 was more excellent than La-modified catalyst if it was heated at 1000°C. The Co 10mol%-Al2O3 catalyst, which was even subjected to a harsh heat condition at 1000°C in air, maintained the NO removal conversion efficiencies of 14% for an lean-bum exhaust of air/fuel ratio (A/F) of 18 (gas mixture; NO, CO, C3H6, CO2, H2O and an excess of O2) at high space velocity 100, 000 h-1 The better activity is caused by Co (+2) doped gamma alumina phase from the solid state reaction in CoOx-Al2O3 system at 800-1000°C.View full abstractDownload PDF (393K) -
Nobuya Machida, Yuki Yoneda, Toshihiko Shigematsu2004 Volume 51 Issue 2 Pages 91-97
Published: February 15, 2004
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSAmorphous solid electrolytes were prepared in the compositions 75 {(1-x)Li2O⋅xLi2S}⋅5P2S5 (mol%) by using a high-energy ball-milling process. The amorphous materials showed lithium ion conductivities higher than 10-3 Sm-1 at room temperature. The amorphous 7.5Li2O⋅67.5Li2S⋅5P2S5 (mol%) sample showed the highest lithium ion conductivity σ298K=2.7×10-2 Sm-1 at room temperature among the obtained samples. An all-solid-state battery was assembled by using the amorphous 7.5Li2O⋅67.5Li2S⋅5P2S5 sample as solid electrolytes. In the battery, TiS2 and Li4.4Si were employed as positive and negative electrode materials, respectively. The discharge-charge cycling test of the battery was carried out at room temperature under a constant current density of 64μAcm-2 with the discharge-charge criteria of voltages 1.1 and 2.6 V. The battery showed successive reversibility with a large specific capacity; the specific capacity calculated on the base of the weight of the TiS2 positive electrode materials was about 170 mAhg-1.View full abstractDownload PDF (579K) -
[in Japanese]2004 Volume 51 Issue 2 Pages 100
Published: February 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (103K) -
Atsushi Hozumi2004 Volume 51 Issue 2 Pages 101-106
Published: February 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSNanoporous ceramic materials, including mesoporous silica (NIPS), fabricated using supramolecular assemblies of surfactant molecules as templates have attracted much attention. In order to obtain nanopores, such organic templates are generally removed from mesostructured organic/inorganic composites by calcination, where the composites are treated in air at a temperature higher than 300°C. However, this conventional process is not suitable, particularly for thin films, since it leads to film shrinkage and generates a considerable amount of internal stress, resulting in distortion or even breakage of the film. We report here a novel approach, which we have named "photocalcination", that achieves the elimination of surfactant molecules from the silica/surfactant composite films while preserving their periodic nanostructures. This method is based on the photochemical decomposition of organic molecules under irradiation with a vacuum ultraviolet light of 172 nm wavelength. Since our process can be conducted at low temperature of about 40°C, nanostructure distortion is much less than that caused by conventional calcination.View full abstractDownload PDF (2098K) -
Tsugio Sato, Shu Yin, Yoshinobu Fujishiro, Kei Hasegawa, Ruxing Li, Sh ...2004 Volume 51 Issue 2 Pages 107-112
Published: February 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSNanoparticles of calcia doped ceria coated with amorphous silica were prepared for UV shielding via soft solution chemical routes at 40-90°C. About 20mol% of CaO could be alloyed with ceria. Doping with calcia resulted in extremely decreasing the particle size (2-4nm), and consequently increasing UV light (λ<400nm) absorbing capacity and transparency in the visible ray region (λ >400 nm). Coating ceria with less than 20 mass% amorphous silica resulted in the decrease in the ceria content, but no noticeable decrease in the UV-shielding ability probably because of the depression of the powder agglomeration. The oxidation catalytic activity of ceria was effectively depressed by both doping with calcia and coating with amorphous silica. The photocatalytic activity of undoped and doped CeO2 was much lower than that of TiO2 and ZnO. The generation of singlet oxygen on CeO2 with UV irradiation in air was also lower than that on TiO2 and ZnO and was greatly decreased by doping with CaO. There was a clear advantage with CaO doped CeO2 coated with amorphous silica compared with other inorganic UV filters because of its excellent UV-absorption capacity, high transparency in visible light and low photocatalytic activity which may safely supply high sun protection factor (SPF) with natural appearance.View full abstractDownload PDF (4752K) -
Jun-ichi Matsushita, Akiko Kitajima, Takashi Akatsu, Eiichi Yasuda, Kw ...2004 Volume 51 Issue 2 Pages 113-117
Published: February 15, 2004
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe high temperature oxidation resistance of boride covered C/C composites was investigated in order to determine the suitability of this composite for high temperature engineering applications. The aim of this study was to give the oxidation resistance performance to the surface of C/C composite covered with SiB6 powder. It was dispersed to a triethyleneglycol in order to coat this samples using the dipping process. The C/C composite samples were obtained with additional mass equal to about SiB6 3 mass% of the total sample mass, and surface of its samples was coated with SiB6 using its process. The high temperature oxidation resistance of C/C composite was drastically improved by covered boride films.View full abstractDownload PDF (2201K)
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