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Volume 55, Issue 3
March
Displaying 1-11 of 11 articles from this issue
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Paper
Memorial Lecture of JSPM Award
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Yoshiaki Kinemuchi, Koji WatariArticle type: Memorial Lecture of JSPM Award
2008 Volume 55 Issue 3 Pages 163-169
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSConstrained sintering, such sintering as thick films on rigid substrates, inherently involves the problem of macro-defect formation viz. crack and/or de-lamination. The origin of these defects lies in a mismatch of sintering shrinkage between different materials. To overcome the problem of film sintering, we have developed a novel sintering process, namely centrifugal sintering. The sintering is capable of applying the centrifugal acceleration of 100000 G during heating procedure. Due to the external pressure generated by centrifugal acceleration, shrinkage behavior of materials shows anisotropy: densification chiefly progresses along thickness direction of the film, while liner shrinkage along in-plane direction is limited. As a consequence, crack-free homogeneous microstructure is accomplished by the present process.View full abstractDownload PDF (1387K)
Review
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Tetsu Takahashi, Koji Matsumaru, Kozo IshizakiArticle type: Review
2008 Volume 55 Issue 3 Pages 170-176
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSOpen-pore porous materials can be produced by the capsule-free Hot Isostatic Pressing (HIPing) process. In this paper, sintering mechanisms, features and applications of capsule-free HIPed open-porous materials are discussed. During sintering powder compacts by capsule-free HIPing process, high pressure gas penetrates inside of the green bodies, and forms pores. There are two mechanisms to explain this phenomenon. Surface-diffusion is enhanced during capsule-free HIPing, because high frequency gas-collision with pore surfaces, forms grown necks between raw powder particles, and enhances pore formation. Another possible mechanism is the matter of spatial compatibility of gas atoms and sintered material. For the shrinkage of pores, i. e., for the densification of the green bodies, the high pressure gas, or the high density gas must be removed from inside of pores. The higher density requires the higher energy to remove high density gas. At the end of the sintering process, the gas must be removed from pores to ambient pressure to make those pores to be open pores. The above mentioned sintering mechanisms provide higher open porosity, more grown necks, smoother pore surfaces and narrower pore size distribution in capsule-free HIPed materials compared with those in conventionally sintered porous materials. As a consequence, high Young's modulus, high fracture strength, high fluid permeability are obtained by the capsule-free HIP process. The porous materials fabricated by the capsule-free HIPing can be applied for filters, grinding wheels, electrochemical electrodes and others with better performance than conventional products.View full abstractDownload PDF (807K)
Paper
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Riei Yokoyama, Satoshi Hayashi, Makoto Nakanishi, Jun TakadaArticle type: Paper
2008 Volume 55 Issue 3 Pages 177-184
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSIn this study, thermal decomposition of Hinoki chips soaked in Ca solution and adsorption properties of obtained charcoal for nitrate nitrogen were investigated to develop a novel functional charcoal. Ca(OH)2 was used as Ca source due to less environmental load and easy handling and Ca-impregnated chips were heat-treated in an electric muffle furnace at temperatures between 600 and 900°C. The Ca-loaded charcoal acid-treated with HCl exhibited adsorptive ability for nitrate nitrogen. It was revealed that adsorption of nitrate nitrogen was ion-exchange reaction and that the charcoal samples acid-treated with HCl could be regenerated repeatedly by exchanging nitrate ion for chloride ion. The measurements of adsorption properties for nitrate nitrogen revealed that the adsorptive ability and durability of these samples were higher than those of activate carbon and anion-exchange resin. It was also found the obtained charcoal exhibited selective adsorption for nitrate nitrogen and fluoride anion, but not for sulfuric acid and phosphoric acid anions. As the result, the simple method, Ca-impregnation, thermal decomposition and acid treatment of wood waste, has advantages in production of nitrate nitrogen adsorption material.View full abstractDownload PDF (1155K) -
Koichi Harada, Tsukio OhtaniArticle type: Paper
2008 Volume 55 Issue 3 Pages 185-191
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSTernary sulfides of BiS(VS2)n (1 ≤ n ≤ 15) were prepared by heating the elemental mixtures in evacuated silica tubes at 1073 K. X-ray diffraction and electron diffraction measurements showed that BiS(VS2)1.50 has a misfit layer structure, where the BiS layers are randomly lacked from the known misfit layer sulfide of (BiS)1.16VS2. BiS(VS2)1.50 has a good conduction, showing a phase transition around 150 K possibly due to the CDW instability. The conduction of BiS(VS2)1.50 was interpreted by the electron donation from BiS into the semiconductive VS2. BiS(VS2)1.50 showed an antiferromagnetic ordering at ca. 30 K, and has a fairly small effective magnetic moments suggesting the strong itinerancy. It was found that the compounds of BiS(VS2)n with 3 ≤ n ≤ 15 have the intergrowth structures composed of BiS(VS2)3 and VS2 phases. Such a great variety of composite materials have never been investigated so far.View full abstractDownload PDF (1266K) -
Effect of Wire Diameter on Particle Size of Metal Nanosized Powder Prepared by Pulsed Wire DischargeYoshinori Tokoi, Tsuneo Suzuki, Tadachika Nakayama, Hisayuki Suematsu, ...Article type: Paper
2008 Volume 55 Issue 3 Pages 192-197
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSCopper, silver and nickel nanosized powders were prepared using metal wires with different diameters in nitrogen gas by pulsed wire discharge. The diameter of the wire was changed from 0.05 to 0.3 mm. The pressure of nitrogen and charged energy were fixed at 100 kPa and 540 J, respectively. After the discharge of the wires, the volume of plasma/vapor measured by high-speed photographs was almost constant even though the wire diameter was changed. On the other hand, the median diameter of copper, silver and nickel nanosized powders was decreased with decreasing the diameter of the wire. Therefore, the decrease in the median diameter accompanies the decrease in the density of the plasma/vapor.View full abstractDownload PDF (1506K)
Special Issue:Materials in Optics and Photonics
Summarization
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Katsuhisa TanakaArticle type: Summarization
2008 Volume 55 Issue 3 Pages 200
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSDownload PDF (144K)
Paper
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Chiwon Moon, Masayuki Nishi, Kiyotaka Miura, Kazuyuki HiraoArticle type: Paper
2008 Volume 55 Issue 3 Pages 201-204
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSWe report on the long-lasting phosphorescence in Ti-doped BaZrO3 perovskite-type crystals (synthesized by a solid-state reaction method). The phosphorescence color is blue and the phosphorescence can still be seen with the naked eye for 30 minutes or more in the dark after stopping UV light. By the measurement of electron spin resonance (ESR) spectra, it was confirmed that the defects of F+ center and Zr3+ exist in the Ti: BaZrO3 and their concentrations decrease with the additive amount of TiO2. It is expected that the luminescence center is FA center composed of Ti3+ and F+ center.View full abstractDownload PDF (596K) -
Ryo Nakajima, Tsuyoshi Honma, Takayuki KomatsuArticle type: Paper
2008 Volume 55 Issue 3 Pages 205-210
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSGlasses in the system of Sm2O3-Gd2O3-MoO3-B2O3-BaO are prepared, and structural changes are induced by irradiations of continuous wave Nd: YAG laser with a wavelength of λ=1064 nm. The optical absorption coefficient of Sm3+ ions at λ=1064 nm in the glasses is found to increase linearly with increasing Sm2O3 contents, and it is clarified that the Sm2O3 content in the glasses must be at least more than 6 mol% in order to induce crystallization under laser irradiations with powers less than P=1 W. The lines patterned by laser irradiations with P=0.8 W and a scanning speed of S=2.5 μm/s consist of a mixture of paraelectric α-SmxGd2-x(MoO4)3 and nonlinear optical β'-SmxGd2-x(MoO4)3 crystals. The formation of only β'-SmxGd2-x(MoO4)3 crystals is confirmed in the lines patterned at P=0.83 W. Although the addition of BaO increases largely the thermal stability against crystallization, the line patterning behavior is not affected significantly at least in the present laser irradiation conditions.View full abstractDownload PDF (727K) -
Norio Kobayashi, Rubin Ye, Takayuki Watanabe, Takamasa IshigakiArticle type: Paper
2008 Volume 55 Issue 3 Pages 211-215
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSHydrogen plasma irradiation technique was applied to improve UV luminescence properties of commercial GaN powder which contained the dissolved oxygen in GaN lattice and a small amount of Ga2O3. RF induction thermal plasma of pulse-modulated mode was used to generate a high concentration of hydrogen radical species. The treatment of a green compact of GaN powder in the tail flame of Ar-H2 PM-ICP gave rise to the increase of photo luminescent intensity at 380 nm. The strongest intensity was obtained when a GaN specimen was set in the plasma tail flame region, where the numerical analysis predicted the increase of hydrogen radical concentration and the decrease of heat flux. When the treatment time increased, partial decomposition of GaN took place in due to excess heat energy. A short time Ar-H2 plasma irradiation gave the appropriate heating and the optimal emission efficiency. Raman scattering spectroscopy showed the impurity Ga2O3 in plasma-irradiated specimens.View full abstractDownload PDF (909K) -
Shigeru Fujino, Koutaro Kunikawa, Toshihisa KajiwaraArticle type: Paper
2008 Volume 55 Issue 3 Pages 216-220
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSTransparent silica glasses were obtained by sintering a green compact in diverse atmospheres. The green compacts were fabricated by slip-casting methods for high-purity silica glass powder. The relationships between sintering atmosphere and sintering temperature that result in transparent, sintered silica glass were shown. It was found that the transparency-forming region of sintered silica glass corresponds to a sintering temperature above 1400°C and high-vacuum (10−4 Pa) atmosphere conditions. We investigate the fabrication of transparent and hydroxyl-free silica glass by a powder-sintered method. The sintered silica glass with 10 ppm OH content exhibited the highest transmittance at 157 nm (76% for 2 mm sample thickness). Refractive index dispersion curves in the wavelength region of 0.194μm to 3.584μm are presented for the sintered silica glass by minimum deviation method.View full abstractDownload PDF (1061K) -
Sonoko Kawase, Sakiko Ukon, Shunsuke Murai, Koji Fujita, Katsuhisa Tan ...Article type: Paper
2008 Volume 55 Issue 3 Pages 221-227
Published: 2008
Released on J-STAGE: October 17, 2008
JOURNAL OPEN ACCESSThermal poling has been applied to 2Ag2O·3Na2O·25ZnO·70TeO2 (in mol%) glass sandwiched in between two commercially-available cover glasses, and precipitation of Ag nanoparticles has been induced selectively in the vicinity of anode-side glass surface. Migration of Na+ during the thermal poling has been investigated by means of energy dispersive x-ray spectroscopy (EDX) to clarify the mechanism of Ag precipitation. The elemental analysis on the surfaces of cover glasses and tellurite glass samples using EDX indicates that the drift velocity of Na+ in the tellurite glass is lower compared to that in cover glass, suggesting that Na+ ions accumulate near the anode-side surface of tellurite glass to facilitate the reduction of Ag+ to Ag. Also, the radius and volume fraction of nanoparticles are evaluated by theoretical fit using Mie scattering theory and Drude free electron theory, and the variation of size and amount of Ag nanoparticles with poling conditions such as poling temperature, time, and voltage is discussed.View full abstractDownload PDF (757K)
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