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Full Paper
published : vol. 128, no.4, April 2020
Kenji SAWAMURA, Kenichiro IWASAKI, Takayuki NAKANISHI, Fumitaka IWAKURA, Yasushi NAKAJIMA, Ken-ichi KATSUMATA and Atsuo YASUMOR
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Luminescent zirconium oxide (ZrO2) with high purity (>3N) was annealed under different oxygen partial pressures (Po2 = 10−14–104 Pa) to investigate the effect of lattice defects on persistent luminescence (PersL). Although the Photoluminescence spectra profiles of samples (broad band emission centered at 485 nm) matched with the PersL spectra, PersL durations differed depending on the value of Po2 during annealing. Samples annealed under a medium value of Po2 such as 1 Pa tended to show long PersL duration. The two main trap levels were evaluated from thermoluminescence glow curves, and the ratio of two traps changed depending on the value of Po2 during annealing. The time profiles of intensities of EPR signals (which assigned to F+-center and hole-trapped oxygen) were linked to the time profiles of luminescence intensities under and after ultraviolet irradiation. This result indicates that the F+-center and hole-trapped oxygen are involved in PersL.
Express Letter
published : vol. 128, no.4, April 2020
Hyoung-Won SON, Philipp SAUERSCHNIG, David BERTHEBAUD and Takao MORI
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Dense YB22C2N samples were directly synthesized from powder mixtures via reactive spark plasma sintering. The gas/solid reaction step was applied to introduce nitrogen into the mixture during heating. The sample reactively sintered at 1700 °C for 10 min after the gas/solid reaction step at 1200 °C for 30 min consisted of YB22C2N with small amounts of secondary phases. The thermoelectric behavior shifted toward n-type behavior with increasing amount of YB22C2N phase. This newly developed synthesis technique could facilitate the rapid and cost-effective preparation of complex borocarbonitrides.
Full Paper
published : vol. 128, no.4, April 2020
Noboru TAKAMURE and David Robert MCKENZIE
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We carry out electric field assisted diffusion of copper ions from metal electrodes into soda-lime glass and demonstrate diffusion at a lower temperature than thermal diffusion. We demonstrate the formation of a spontaneous potential difference when the glass is reheated between non-contacting electrodes, and show how this technique, termed Thermal Relaxation Ion Electro-Spectroscopy,1 when combined with energy dispersive analysis in scanning electron microscopy can be used to understand aspects of the diffusion process. We find strong interactions between copper and the other ions in glass that cause local concentration maxima in these ions. Thermal annealing of copper diffused glass leads to a uniform concentration of copper that may be useful for device applications. Copper ions obey the same Meyer-Neldel rule2 as other metals when diffusing in glass.
Full Paper
published : vol. 128, no.4, April 2020
Dong HAO, Takashi AKATSU and Nobuaki KAMOCHI
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The water absorption (WA) and pyroplastic deformation (PD) of alumina-strengthened porcelain with talc-addition is examined to develop porcelain with optimized properties for a wide range of firing temperatures. An increase in talc amount enhances the porcelain densification, i.e. decreases WA and the increase in sintering shrinkage which accelerates PD, because it leads to an increase in the amount of liquid phase with a low viscosity during firing. On the other hand, talc and Gairome clay addition yields rigid crystalline microstructures in the glass matrix of the porcelain, which suppresses PD. As a result, optimized properties, i.e. WA less than 0.5% and pyroplastic deformation index less than 1.5 × 10−6 mm−1, are realized in porcelain with 2 mass % talc addition in a wide firing temperature range from 1240 to 1384 °C.
Full Paper
published : vol. 128, no.4, April 2020
Li ZHANG, Yingjie JIN, Feixue LIANG, Ruijiang FENG, Ping LI, Xuebo ZHAO, Sachio ASAOKA and Kaoru FUJIMOTO
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This study aims to prepare the Jilin-Davy-Faraday, Layered solid no.1 (JDF-L1) type of layered materials and to elucidate the role of fluoride mineralizing agents in inducing crystal orientation growth featuring lamellar textures. The layered zeotypes synthesized by fluoride routes were characterized by several techniques, viz. X-ray diffraction, fourier transform infrared spectroscopy, field emission scanning electron microscopy, 27A1 and 29Si magic angle spinning-nuclear magnetic resonance, etc. The JDF-L1 crystals were shown to crystallize in the uniform habit of square-sheet structures when the fluoride synthesis systems adopted a lower initial alkalinity and reduced crystallization temperatures. This method facilitated both the isostructural incorporation of tetrahedral [AlO4] or [FeO4] for unique SiO4 units and also allowed the orientation growth of lamellar Al(Fe)-JDF-L1 crystals. Isomorphous substitution of trivalent Al or Fe was likely to perturb the JDF-L1 structure and hence caused the orthogonal multiplication of smaller lamellar subindividuals onto the basal crystal surfaces.
Technical Report
published : vol. 128, no.4, April 2020
Takuya HIROSAWA, Toshihiro ISOBE, Sachiko MATSUSHITA and Akira NAKAJIMA
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Rod-like cerium dioxide (CeO2) powder was prepared using hydrothermal processing. Then ceria thin films were prepared by coating of ethanol suspensions with a sublimation agent and a mixture of the rod-like ceria with commercial irregular nanoparticles onto glass substrates, followed by firing. Transparent superhydrophobic ceria films were obtained from samples with more than 50% rod-like ceria after coating hydrophobic fluoroalkyl silane on the surface. Both sliding angles and contact angles increased concomitantly with increase of the ratio of rod-like ceria. The trend of the contact angle increase was rationalized by the increase of the pore structure in the film. The sliding angle increase was accountable by consideration of the depth of droplet penetrating into the surface obtained by assuming normal pillar-array structure models calculated from the packing of particles with a high aspect ratio.
Note
published : vol. 128, no.4, April 2020
Masaki KAKIAGE, Taiju KOBAYASHI and Kazuma YABUYA
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Fibrous crystalline boron carbide (B4C) was fabricated by carbothermal reduction starting from electrospun condensed boric acid (H3BO3)-poly(vinyl alcohol) (PVA) product fibers. The addition of hydrochloric acid to a H3BO3-PVA/dimethyl sulfoxide solution resulted in electrospinnability of the solution; thus, condensed H3BO3-PVA product fibers were prepared by electrospinning. The fibrous B4C precursor was prepared by the thermal decomposition of the electrospun H3BO3-PVA product fibers in air. The fibrous B4C was obtained by heat treatment of the fibrous precursor at 1400 °C in an Ar flow. The structure of fibers in fibrous B4C consisted of connected particles.
Note
published : vol. 128, no.4, April 2020
Tatsuro HORIUCHI and Kazuki YOSHIMURA
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In this study, we investigated the solar heat gain coefficient of aluminum-doped ZnO (AZO) low-emissivity (low-e) glass. Silver-based low-e glass has excellent solar heat shading performance. However, this is undesirable in winter. When the outside temperature is low, low-e glass should allow the passage solar heat into a building. Transparent conductive oxides can be applied for this purpose, as they transmit near-infrared light. Indium tin oxide (ITO) has already been used in this way. However, ITO is toxic, and the availability of indium is limited, making it expensive. As an alternative material, AZO is promising. We fabricated AZO films on glass substrates and measured their transmittance, specular reflectance and absorbance. The solar heat gain coefficient and the heat transmission coefficient were then calculated.
Note
published : vol. 128, no.4, April 2020
Kunihiko KATO, Yunzi XIN, Takashi HITOMI and Takashi SHIRAI
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Fly ash (FA), an environmental pollutant created in combustion of coal for energy production, is generated in huge amounts worldwide every year. Among the considerable number of utilizations, FA has been used as a suitable silicon (Si) and aluminum (Al) supplier in synthesis of geopolymers. We previously reported a detailed study on surface modification of FA via mechanochemical (MC) treatment with regard to the dissolubility dynamics of Si and Al ions in alkali solutions. Here, we present the fabrication of solidified bodies using MC-modified FA with a low-concentration alkali solution at low temperature as a practical application. In addition, the chemical states of Si and Al in MC-modified FA powders and solidified bodies were systematically investigated further, showing them to be well-correlated with the dissolubility of FA powders and mechanical strength of solidified bodies.
Note
published : vol. 128, no.4, April 2020
Koji KURAOKA, Yuta SHIMMEN, Hidetoshi KATO, Hiroyasu SEKI and Takeshi NISHIKAWA
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Organic–inorganic hybrid gas barrier layers using 3-glycidoxypropyl silsesquioxane with random structures on plastic film were prepared by cross-linking reaction between glycidoxy functional group of 3-glycidoxypropyl silsesquioxane and amino functional group of p-xylylenediamine (PXDA). The effects of PXDA content on the gas barrier property of the membranes were investigated. Oxygen permeability coefficient and water vapor transmission rate of the hybrid layer were the same order of poly(vinylidene chloride). Pencil hardness (750 g load) of the hybrid layers on the polyethylene terephthalate (PET) substrate were HB. The pencil hardness of the PET was B. Thus, the pencil hardness of the hybrid layers was slightly higher than that of PET. These characteristics were attributed to the sufficient dispersion of inorganic segments (siloxane network, –Si–O–Si–) and organic segments in the hybrid.

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