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鄂 剛, 竹内 信行, 石田 信伍, 細川 和芳, 山崎 憲治, 鬼頭 範光, 並河 康訓, 新見 秀明
1996 年 104 巻 1216 号 p.
1091-1096
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
Degradation of positive temperature coefficient of resistivity (PTCR) properties of semiconducting BaTiO
3 ceramics that were annealed in reducing gases was studied from a mechanistic viewpoint mainly by measuring the electrical and dielectric properties, using reflectance and ESR spectroscopies, as well as by gas analysis using a quadrupole mass spectrometer. The results showed that after annealing, the density of the surface acceptor states decreased whereas the concentration of conduction electrons increased. The degradation in PTCR, properties was assumed to be caused by the diffusion of hydrogen atoms that were formed from reducing gases along the grain boundaries. These atoms reacted with chemisorbed oxygen ions, releasing trapped electrons and lowering the barrier potential.
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金 大原, 河村 雄行, 榎本 尚也, 中川 善兵衛
1996 年 104 巻 1216 号 p.
1097-1099
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
A molecular dynamic (MD) simulation with a new potential model has been performed to investigate the structural change of germanium dioxide under high pressure. A phase transition of α-quartz-type GeO
2 crystal was found over 6.0GPa at 300K. This transformation involves an abrupt volume shrinkage according to the increase of the coordination number of germanium. It is shown that the MD simulation results are in good agreement with the experiment.
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音石 真二, 丹下 善弘
1996 年 104 巻 1216 号 p.
1100-1105
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
SiC whiskers were obtained from the porous bodies produced from polymerizable W/O-type emulsions containing polycarbosilane and milled carbon fibers by the heat treatment at 1273 to 1623K in Ar. The whiskers were deposited on the surface and inside of the porous bodies. The whiskers were found to be β-type SiC whiskers by X-ray diffraction analysis. The whiskers obtained by the heat treatment at 1623K had diameters from 0.2 to 0.6μm and lengths from 10 to 50μm. Scanning electron microscopic analysis revealed that SiC whiskers grew by the vapor-liquid-solid (VLS) process.
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木口 賢紀, 佐伯 淳, 篠崎 和夫, 水谷 惟恭
1996 年 104 巻 1216 号 p.
1106-1111
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
Electrochemically reduced 3mol% Y
2O
3-ZrO
2 crystals were unidirectionally compressed in the range of 100 to 1000MPa at temperatures from 550 to 800°C to examine the effect of oxygen vacancy on ferroelastic domain switching. The switching amount of all the samples increased with increasing temperature. The switching amount of the cathode-side of reduced samples was less than that of the anode-side and as-grown samples compressed under the same stress. These results were interpreted using the model in which oxygen vacancy pins the domain wall. Domain switching occurred stepwise, and the critical stress was not influenced by the oxygen vacancy introduced by reduction.
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安藤 正美, 土田 敬之, 須藤 誠一, 鈴木 貴弘, 中山 千秋, 三浦 則雄, 山添 昇
1996 年 104 巻 1216 号 p.
1112-1116
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
Thick films of Au-loaded WO
3 mixed with glass frit were prepared on an alumina substrate by the printing method, and influences of film thickness, Au-loading and operating temperature on the NH
3 sensing characteristics were investigated. With an increase in film thickness and Au-loading, the maximum sensitivity (
Km) increased, while the temperature for maximum sensitivity (
Tm) decreased. An optimum film was revealed to be the 4.0mass% Au-loaded one of a 250μm-thickness for the optimum operating temperature of 450°C. The sensor proved excellent NH
3 sensing characteristics in gas sensitivity, response transient, resistance to humidity and long-term stability when subjected to heat cleaning once a day during its operation.
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宍戸 統悦, 葉 金花, 佐々木 孝彦, 松本 武彦, 福田 承生
1996 年 104 巻 1216 号 p.
1117-1120
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
The single crystals of a new quaternary compound ErRh
2B
2C have been obtained as thin plates in an atmosphere of helium by the flux method using molten copper. The single crystals show golden-colored luster and the maximum size obtained is about 1.0×1.0×0.02mm
3. This compound belongs to a tetragonal system and seems to be a derivative of ThCr
2Si
2 type; lattice parameter:
a=0.36848(2)nm,
c=1.05520(3)nm,
V=1.4327×10
-28m
3 and
Z=2. The electrical resistivity parallel to the
a-b plane decreases monotonically with decreasing temperature, but no superconductivity is observed down to 1.5K. The residual resistivity ratio, ρ(273K)/ρ(1.5K), is 1.38. Similar type new compounds of RRh
2B
2C were obtained for R=La-Er (except Eu and Tm) and Y by arc-melting synthetic method.
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橋本 忍, 戸田 誠治, 山口 明良
1996 年 104 巻 1216 号 p.
1121-1124
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
MgO and Cr
2O
3 powders were mixed in various ratios and pressed to form compacts. They were heated in the carbon powder bed. Starting compacts containing 53 to 63mol% Cr
2O
3 were densely sintered, particularly the sintered compact with 55mol% Cr
2O
3 was about 93% in relative density, and composed of (Mg
8-xCr
x)Cr
16O
32 (0≤
x≤2.88). Pores with globular shape in the compacts suggested the sintering in the presence of a liquid. Under reductive atmosphere coexisting with carbon, a liquid of the Cr-Cr
2O
3-MgO system is considered to form due to reduction of the Cr
2O
3 in the compact. During cooling, the (Mg
8-xCr
x)Cr
16O
32 may precipitate from the liquid. When the compound was exposed to air during heating, this phase was unstable and changed to MgCr
2O
4 and Cr
2O
3 at about 300°C.
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堀内 達郎, 杉山 豊彦, 水野 敬介, 尾崎 利彦, 鈴木 憲司, 渡村 信治, 森 聰明
1996 年 104 巻 1216 号 p.
1125-1128
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
In order to suppress the lead leaching from porcelain tableware, silica-coating on overglaze decoration by the sol-gel process was tried. The silica thin films were dense and it was suggested that the micropores larger than 0.36nm (kinetic diameter of N
2 molecule) did not exist. Only in the case a sol aged for a long time, micropore (pore diameter: 0.7nm) formation was observed. By the coating of the silica thin films which had no pores accessible for N
2 molecule, lead leaching was suppressed to large extent. In the case of silica thin film with micropores of 0.7nm in diameter, the amount of lead leached was almost the same as that of the specimen without coating. This tendency was due to the easiness of the diffusion of Pb
2+ hydrated ion through the coating films depending on the relative size of Pb
2+ hydrated ion (0.46nm) and the pore diameter.
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小栗 康生, 安達 隆二, 戸野 秀夫, 中島 教夫, 遠藤 忠
1996 年 104 巻 1216 号 p.
1129-1132
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
Red light emitting phosphors (Y, Eu, Ln)
2O
2S were crystallized in (Li
2CO
3+S) fluxes containing various rare earth ions such as La
3+, Nd
3+, Gd
3+, Yb
3+ and Lu
3+. According to the SEM observations, the grain size of (Y, Eu)
2O
2S was decreased by adding La
3+, Nd
3+ or Gd
3+ ions, but increased by adding Yb
3+ or Lu
3+ ions. Such a profile was closely related to the changes of the unit cell parameters of (Y, Eu, Ln)
2O
2S. Addition of La
3+ ions has given little effect on the luminescent properties and the formation reaction mechanism of (Y, Eu)
2O
2S. Furthermore, the minimum grain size of (Y, Eu)
2O
2S phosphor was obtained at 3mol% of La
3+ doping. The flux growth mechanism was disscussed in the formation process of oxysulfides.
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原田 朋幸, 池田 法民, 太田 敏孝, 引地 康夫, 鵜沼 英郎, 高橋 実, 鈴木 久男
1996 年 104 巻 1216 号 p.
1133-1136
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
PTC materials composed of particles of conducting graphite and insulating cristobalite-form SiO
2 or AlPO
4 were prepared by the use of silicone rubber as a binder. The PTC effect was observed exactly at the reversible phase transition point with a large thermal expansion of cristobalite (ca. 270°C in SiO
2 and ca. 230°C in AlPO
4), and was reproducible on repeated runs. The magnitude of the PTC effect was high in composites having a middle composition between insulator and conductor in the percolation curve.
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伊藤 秀章, 志村 禎徳, 岩原 弘育, 坂本 弘道
1996 年 104 巻 1216 号 p.
1137-1142
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
The effects of CVD parameters and preparation process on the adherent coating of diamond on a pretreated silicon nitride substrate were investigated by the two-stage microwave plasma CVD in the CO-H
2 system. Fine-grained diamond was deposited by the first stage CVD into the micropores of the surface layer of the substrate, which was pretreated by etching in a hot strong acid (HF and HNO
3) solution and subsequently by microflawing with diamond grains in an ultrasonic bath. Excellently adherent and thick diamond coating was prepared by the second stage CVD for long term durations. Long tool life was verified by the milling test of the diamond-coated specimens using Al-20 mass% Si alloy as work material.
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伊賀 武雄
1996 年 104 巻 1216 号 p.
1143-1146
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
The effect of solid concentration on slip-cast density have been investigated for three alumina powders with different particle size distributions. It was clearly observed in the powder with the multi-modal particle size distributions, but slightly in that with a monosize distribution. Once a slip was prepared with a higher solid loading for a long period to proceed homegeneity, no further notable decrease in density with decreasing in solid loadings was observed even for the multi-modal powders. The low green density casted from the slurries with the low solid loadings is attributed to the inhomogeneity that arise mainly from insufficient mixing. Therefore, it is more important for the raw materials with the particle size distributions which are expected to have the higher particle packing density.
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伴野 巧, 佐野 三郎, 小田 喜一, 芝崎 靖雄
1996 年 104 巻 1216 号 p.
1147-1150
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
A uniaxial compression test was carried out to investigate deformation behavior of clay green body for wet-pressing. Green bodies containing 25-35 mass% water were prepared from Hara gairome clay and distilled water. The samples were formed into column having various dimensions (20mmφ×30mm
h, 20mmφ×15mm
h, 20mmφ×10mm
h, 33mmφ×10mm
h) and were largely deformed by compression under a compression rate of 1.0mm·s
-1. When the stress-strain curves were converted to the stress-diameter/height curves according to the plastic deformation theory, the yield points and the linear relationships between stress and diameter/height were observed, which were well represented by a plastic deformation equation of uniaxial compression under full-surface-sticking, since the ratio of the slope of the line over the yield point were close to 0.19. The yield points increased with decreasing water content. The sticking was due to the adhesion between the steel die and the samples. In conclusion, it is found that the compression deformation of clay green body can be well characterized by using a uniaxial compression test.
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アルミナの粒径・形状が緻密化と曲げ強度に及ぼす効果
原田 隆介, 杉山 紀幸, 進 博人, 石田 秀輝
1996 年 104 巻 1216 号 p.
1151-1155
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
The effects of size (0.88-11μm) and shape of alumina particles on the densification, flexural strength and microstructure were investigated in the quartz-feldspar-kaolinite system. Relative density and flexural strength were demonstrated to have linear relationships and the slope of these lines (κ-value) was dependent upon the size and shape of alumina particles. The flexural strength reached its maximum value when particles of 2μm diameter were used. This phenomenon is explainable for coarse alumina due to the enlargement of the Griffith flaw for a small number of particles, but can not be explained in the case of fine alumina. The shape of alumina particles did not affect the flexural strength or the fracture toughness in any of our experiments.
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池田 攻, 中邑 義則, 島 敞史
1996 年 104 巻 1216 号 p.
1156-1157
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
Calcium monosulfate hydrates, Ca
4[Al
2(OH)
12][(1-
x)SO
4⋅
x(OH)
2]⋅6H
2O were synthesized at 20°C from aluminate haüyne, Ca
8Al
12O
24(SO
4)
2 by hydration under the presence of gypsum and portlandite. The experimental water/solid ratio was 0.80. Quantitative analysis by EPMA revealed that the
x reaches up to 0.16 under the present synthetic conditions where ettringites are considered to be stable at lower water/solid ratios. Stabilities of accompanied phases were discussed in terms of phase assemblage.
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平塚 信之, 細井 明子, 小林 裕, 柿崎 浩一
1996 年 104 巻 1216 号 p.
1158-1159
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
Bulk gas sensors composed of various atomic ratios of ZnO and SnO
2 were fabricated and their gas sensing characteristics were investigated. After powder mixtures of ZnO and SnO
2 together with equal weights of camphor were pressed into disks, they were sintered at 1200°C for 3h in air. The relationship between the atomic ratio of ZnO and SnO
2 and the gas sensing characteristics was investigated. As a result of the measurements of the conductance of these gas sensors upon exposure to 2vol%
i-C
4H
10 gas, the sensor consisting of Zn:Sn=0.68:0.32 was found to have the highest sensitivity. After the atmosphere was changed from
i-C
4H
10 to air, the conductance returned to almost the initial level within 1min.
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川村 浩敏, 奥戸 清市, 樽田 誠一, 田草川 信雄, 北島 圀夫
1996 年 104 巻 1216 号 p.
1160-1162
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
Porous glass, having a pore size of around 10nm in diameter, was prepared from fluorine containing sodium borosilicate glass by treatments of phase-separation and acid leaching. A titanium oxide was anchored onto a platelet porous glass specimen of 0.5mm in thickness by impregnating with aqueous solution of titanium (III) chloride or titanium (IV) sulfate. The distribution of titanium concentration was homogeneous in the porous glass specimen as dried. However, in the specimen which was impregnated with a larger amount of TiO
2 and heated in the temperature range of 200 to 500°C. The Ti-distribution was inhomogeneous showing a higher Ti-content in two areas on both side of the center of specimen.
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鈴木 一孝, 中野 喜久男, 粂 正市, 西野 洋一
1996 年 104 巻 1216 号 p.
1163-1166
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
Three-dimensional (3D) carbon fiber reinforced SiC composites have been fabricated by using slurry infiltration and repeated infiltration of organosilicon (polycarbosilane) resin. Open porosity of the infiltrated body was decreased from 34% after the first slurry infiltration to about 10% after the eighth infiltration of poly-carbosilane. Relative density of the composite increased to 89%, in spite of densification under normal pressure without sintering additive. The maximum values of flexural strength and fracture toughness were 160MPa and 7.5MPa·m
1/2, respectively.
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野村 研二, 川合 智司, 柴田 典義
1996 年 104 巻 1216 号 p.
1167-1170
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
Interface reaction between Au film and single-crystal α-Si
3N
4 was analyzed with depth profile by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). Diffusion of Si from the Si
3N
4 to the Au film surface was observed by SIMS. Clear evidence which indicates low-temperature (600°C) solid reaction between Au and Si
3N
4 was also observed. The interface region exhibited peaks corresponding to Au-Si bond, Si-N bond and dangling nitrogen bond in the XPS spectra. It is considered that the Au-Si bond was formed by dissociating Si-N bond, and the reaction mechanism is similar to Au-Si reaction at Au/Si in-terface. In the case of Au and amorphous SiN
x, the interface reaction was more remarkable than that of the single-crystal Si
3N
4.
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広崎 尚登, 安藤 元英, 岡本 裕介, 宗像 文男, 秋宗 淑雄, 平尾 喜代司, 渡利 広司, Manuel E. BRITO, 鳥山 ...
1996 年 104 巻 1216 号 p.
1171-1173
発行日: 1996/12/01
公開日: 2010/08/06
ジャーナル
フリー
Thermal conductivity of sintered silicon nitride has been improved by the alignment of large β-Si
3N
4 grains. Beta-Si
3N
4 containing 0.5mol% Y
2O
3 and 0.5mol% Nd
2O
3 was seeded with rodlike β-Si
3N
4 grains and tape-cast to align the seed grains. In-situ composite microstructure of the aligned large grains in smaller matrix grains was developed by the grain growth of seed grains during gas-pressure sintering at 2200°C for 4h. Room-temperature thermal conductivity was anisotropic: 137W·m
-1·K
-1 in the direction of tape-casting, 97W·m
-1·K
-1 of seet width, and 72W·m
-1·K
-1 in the direction of seet stack. The thermal conductivity in the direction parallel to the tape-casting direction was high because of the aligned large grains.
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