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Full Paper
published : vol. 128, no.5, May 2020
Taka ANDO, Yuta SATO, Takuya MATSUYAMA, Atsushi SAKUDA, Masahiro TATSUMISAGO and Akitoshi HAYASHI
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All-solid-state lithium-sulfur batteries are promising from the perspective of high safety, low cost, and high capability. Herein, composites of sulfur and microporous carbon (MSP20, MSC30) are prepared by a melt diffusion process, and their performance as electrode materials are compared with that of composites based on nanocarbons. In addition to the type of carbon, the degree of mixing with solid electrolytes is an important factor in the formation of ionic/electronic conduction pathways. The all-solid-state cell using S-MSC30-Li3PS4 shows a high initial discharge capacity of 1488 mAh per gram of sulfur at 25 °C at a current density of 1.3 mA cm−2 and operates reversibly at a high current density of 12.7 mA cm−2 (3C) at 100 °C. The amorphization of sulfur is effective for obtaining high capacity and sulfur impregnated into the meso- and micropores of carbon is more active than sulfur that forms nanocomposites with nanocarbon.
Review
published : vol. 128, no.5, May 2020
Zhenzhen WANG, Baomin WANG, Daling YANG and Junnan HAN
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As chloride ions ingress into cement-based composites, the service life of the cementitious materials will be negatively affected when the part overloading the content threshold of chloride ion can not be bound by hydrated products in cement-based materials. This paper doesn’t only indicate the chloride binding capability as well as the various effects of comprehensive influential factors correspondingly. But it also elucidates different chloride binding mechanisms of various cement matrix materials. In addition, the relationship between chloride binding and chloride permeability was also reconsidered in this paper. Especially, for the prediction to service life-span of reinforced concrete structures with chlorination, the authors reflect on the contribution of the chloride binding. Ultimately, on the basis of considerable significant existing researches some vital issues and challenges with relevant countermeasure are proposed by the authors.
Full Paper
published : vol. 128, no.5, May 2020
Zhiyong HE
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Calcined flint clay has a large reserve in China. In this paper, porous mullite ceramics are prepared by calcined flint clay, while the sawdust is pretreated with different concentrations of silica sol. Effects of sintering temperature and silica sol concentrations on physical properties and microstructures of the porous mullite ceramics are studied. Residual skeleton structure cross pores are clearly observed in the scanning electron microscope images, which is established as a key factor in improving the properties of specimens. With the pretreatment of silica sol on sawdust, mechanical properties are enhanced and thermal conductivities could be optimized. Under the firing temperature of 1350 °C, the compressive strength of specimens with sawdust pretreated in 5 wt % concentration of silica sol is 2.4 MPa.
Full Paper
published : vol. 128, no.5, May 2020
Saho KIMURA, Yuki KANEKO, Kazuhiro MARUMOTO and Yoshikazu SUZUKI
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Li2CoTi3O8 has a spinel-type crystal structure, and it can be simply synthesized by a solid-state method using Li2CO3, CoO and TiO2. Li2CoTi3O8 is currently used as a cyan-colored pigment, and it is highly safe as is actually utilized for cosmetics. In this paper, we have studied the color development mechanism of Li2CoTi3O8 with changing the synthetic temperatures, using X-ray diffraction (XRD), CIE-L*a*b* color coordinates, hue angle h, UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR). Li2CoTi3O8 formation was partially confirmed even at 500 °C, and single-phase Li2CoTi3O8 was obtained at 950–1200 °C. All the samples synthesized at 750–1200 °C located in the cyan color zone (h ∼ 195–235°). The color change with synthetic temperatures, from whitish to deep cyan, was well explained by the visible light absorptions of Co2+ ions with different coordinations.
Full Paper
published : vol. 128, no.5, May 2020
Kosuke HASHIMOTO, Daiki SHIRATORI, Daisuke NAKAUCHI, Takumi KATO, Noriaki KAWAGUCHI and Takayuki YANAGIDA
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We successfully synthesized Tl-doped SiO2 glasses by the spark plasma sintering method, and the prepared glasses doped with various concentration of Tl were studied for optical, scintillation, thermally-stimulated luminescence (TSL), and optically-stimulated luminescence (OSL) properties. The Tl-doped samples indicated photoluminescence (PL) due to Tl+ ions characterized as an emission peak around 310 nm. The PL decay time constants ascribed to the emission from Tl+ were 0.56–0.60 µs. In the scintillation, an emission peak due to Tl+ was observed as well as the PL. The highest PL quantum yield and light yield among the present samples were 10.2% and 1100 photons/MeV under 241Am α-ray exposure, respectively. Moreover, the Tl-doped samples showed the TSL and OSL emission peak caused by Tl+ and the dynamic range in OSL was confirmed from 0.01 to 100 mGy.
Full Paper
published : vol. 128, no.5, May 2020
Takuya AOYAGI, Daiko TAKAMATSU, Yohei ONODERA, Takashi NAITO, Taigo ONODERA, Tatsuya MIYAKE, Shinji KOHARA, Toshiaki INA, Yamato HAYASHI and Hirotsugu TAKIZAWA
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Understanding the mechanism behind the water durability improvement of phospho-vanadate glass is crucial for enabling the practical use of low-melting glass in lead-free sealing and secondary ion batteries. We demonstrate that Fe2O3 additive is a key component for improving the water durability while suppressing the rise of the glass transition temperature of V2O5–P2O5 (VP) glass, and characterize the local structural change by X-ray absorption fine structure measurements. In VP glass, the addition of Fe2O3 increases the coordination number of vanadium ion without changing the oxidation state. The water durability is relatively sensitive to the vanadium valence and coordination environment compared to the glass transition temperature and hardness. Minimizing V5+O4 units in phospho-vanadate glass is the key to improving the water durability.
Full Paper
published : vol. 128, no.5, May 2020
Hiroyuki INOUE, Atsunobu MASUNO, Atsuki SAITO, Yasuhiro WATANABE, Kazuya TOKUDA, Yoshihiro SAITO and Junji IIHARA
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The local structure around Eu3+ ions in Eu-doped glasses prepared by a levitation technique was analyzed by X-ray absorption fine structure spectroscopy. The X-ray absorption near edge structure spectra demonstrated that Eu3+ ions in Al2O3–SiO2 binary glasses were partly reduced during high-temperature melting. Extended X-ray absorption fine structure spectra indicated that in La2O3–Nb2O5, La2O3–Al2O3, and La2O3–TiO2 glasses that contained a large amount of La2O3, the bond lengths between Eu and O were distributed from 2.34 to 2.39 Å. The coordinated polyhedra around the Eu ions could be fitted to a single coordination sphere. It was found that the bond lengths tend to become shorter as the optical basicity of the glass increases. In the Al2O3–SiO2 glasses without any network modifiers, the local structure around the Eu was more complex, leading to the broader first correlation peak of radial structure function.
Full Paper
published : vol. 128, no.5, May 2020
Dong HAO, Takashi AKATSU and Nobuaki KAMOCHI
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The effect of cordierite crystallization on the densification and pyroplastic deformation (PD) of alumina-strengthened porcelain that contains talc is examined herein. During firing at a relatively low temperature below 1200 °C, the addition of fine talc powder with a mean diameter of approximately 7 µm is more effective in promoting the liquid phase sintering of the porcelain through an increase in the amount of the low-viscosity liquid phase due to Mg2+ doping than the addition of a coarse talc powder with a mean diameter of approximately 14 µm. Beyond the firing temperature, cordierite crystallization that is accelerated by the fine talc addition suppresses the PD of the porcelain through a decrease in the amount and an increase in the viscosity of the liquid phase due to the transfer of Mg2+ from the liquid to the cordierite crystals. As a result, a decrease in the water absorption (<0.5%) and PD index (<1.5 × 10−6 mm−1) is realized for the porcelain with 32 mass % addition of the fine talc powder over a relatively wide firing temperature range from 1194 to 1336 °C.
Full Paper
published : vol. 128, no.5, May 2020
Teruaki FUCHIGAMI, Ryosuke KIMATA, Masaaki HANEDA and Ken-ichi KAKIMOTO
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Raspberry-shaped Co3O4 nanoparticles has a great potential as a CO oxidation catalyst in a wide temperature range because of a high stability and a low-temperature oxidation activity. In this study, primary particle sizes, morphology and crystallite sizes were controlled by changing a synthesis time to enhance the CO oxidation activity and to reveal growth mechanism of the raspberry structure. The primary particle sizes increased while decreasing crystallite size, indicating crystal orientation and particle growth of Co3O4 nanoparticles were occurred in multistage, and a single-crystal-like structure formed in the hydrothermal treatment for 3.0 h. Long-time hydrothermal treatment for 12.5 h caused decomposition of the crystallographic orientation and the raspberry structure. H2-temperature programmed reaction analysis indicated that crystal orientation among multiple Co3O4 nanoparticles improved a mobility of bulk oxygen species, and our previous findings that 93% of CO conversion rate for the raspberry-shaped Co3O4 nanoparticles was confirmed analytically by the high oxygen mobility in the early 3.0 h-hydrothermal treatment.
Full Paper
published : vol. 128, no.5, May 2020
Yasuhiro SHIRAHATA
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Effects of annealing temperature on photovoltaic properties of lead-free (CH3NH3)3Bi2I9 solar cells were investigated. The (CH3NH3)3Bi2I9 photovoltaic cells were fabricated by a hot air blow-assisted spin-coating method. The spin-coated (CH3NH3)3Bi2I9 photoactive layers were annealed at temperatures of 100–150 °C. Current density–voltage characteristics of the (CH3NH3)3Bi2I9 photovoltaic cells showed that conversion efficiency increased with increasing annealing temperature. Microstructures and optical properties of the (CH3NH3)3Bi2I9 photoactive layers were also investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and ultraviolet–visible–near infrared spectroscopy. The investigation revealed that the changes in lattice constants, crystallite size, surface morphology, and iodide/bismuth ratio of the (CH3NH3)3Bi2I9 were attributed to the annealing temperature, resulting in the changes in the photovoltaic properties of the (CH3NH3)3Bi2I9 solar cells.
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.