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The 71st CerSJ Awards for Academic Achievements in Ceramic Science and Technology: Review
Special Article
published : vol. 125, no.12, December 2017
Yoshinobu FUJISHIRO
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Electrochemically active ceramic anodes for next-generation solid oxide fuel cells (SOFCs) were studied by controlling the anode structure at the submicro-scale. Specifically, the effect of highly porous metal-ceramic structures on electrochemical properties such as power density and conversion efficiency at an intermediate temperature was investigated. Moreover, the structural control technology of active fuel electrodes for direct hydrocarbon SOFCs was discussed. In addition, high-temperature steam solid oxide electrolysis cells (SOECs) with highly porous fuel electrodes have been developed for advanced ceramic reactors.
The 71st CerSJ Awards for Academic Achievements in Ceramic Science and Technology: Review
Special Article
published : vol. 125, no.12, December 2017
Naoki WAKIYA, Takahiko KAWAGUCHI, Naonori SAKAMOTO, Harinarayan DAS, Kazuo SHINOZAKI and Hisao SUZUKI
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When a focused laser beam is irradiated onto a target, electrons and cations are emitted from the target to form a plume (plasma). This phenomenon is referred to as laser ablation (LA). The thin film deposition method using laser ablation is referred to as pulsed laser deposition (PLD). Recombination of electrons and cations usually occurs in the plume before they arrive at a substrate to form a thin film. However, previous reports show that applying a magnetic field to the plume suppresses recombination and enhances electron-impact excitation. The flux of electrons and cations can therefore be controlled by an external magnetic field during PLD. Charged cations can separate from neutral particles or heavy clusters such as droplets. This principle has been used to obtain droplet-free thin films. Applying a magnetic field to the plume also causes ohmic heating and suppression of adiabatic expansion. The electron temperature in a plume with magnetic field application is therefore higher than that in a plume without magnetic field application. This principle has been used to lower crystallization temperatures, improve crystallinity, and enhance thin film properties. Because application of a magnetic field suppresses recombination and enhances electron-impact excitation, several cations exist in the plume. These then rush to the substrates. This principle produces changes the growth mode, which in turn brings about changes in the thin film morphology. Furthermore, this principle leads to phase separation control. The impingement of cations reportedly brings about lowering of the activation energy for diffusion, which leads to phase separation by spinodal decomposition. A thin film with a spontaneous superlattice structure forms when compositional wave propagation occurs in one direction, but when a cross-linked microstructure is obtained the compositional wave direction of propagation is random. This review presents the influence of application of a magnetic field during deposition.
Full Paper
published : vol. 125, no.12, December 2017
Ke BAO, Liangxu LIN, Hong CHANG and Shaowei ZHANG
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Calcium hexaboride (CaB6) nanoparticles were prepared via low temperature magnesiothermic reduction of CaO and B2O3 in molten NaCl, KCl or CaCl2. The effects of salt type, Mg amount, and firing temperature and time on the reaction extents were examined, and the responsible reaction mechanisms were discussed. Under an identical firing condition, CaCl2 facilitated the overall synthesis more effectively than the other two salts. In the case of using 20 mol % excessive Mg, phase-pure CaB6 nanoparticles of ∼50 nm were formed in CaCl2 after 6 h at 800°C. The “dissolution-precipitation” mechanism is believed to be responsible for the molten salt synthesis of high quality nanosized CaB6 particles at such a low temperature.
Full Paper
published : vol. 125, no.12, December 2017
Issei SUZUKI, Masatoshi TANEMURA and Takahisa OMATA
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The β-NaGaO2 thin film is a precursor film for the fabrication of a β-CuGaO2 thin film by ion exchange, which is expected to be applicable to a thin film solar cell. The β-NaGaO2 thin films were fabricated by electron beam evaporation, and they showed substrate dependence of the crystal orientation, which is in contrast to the recently reported β-NaGaO2 films obtained by sputtering that exhibited no substrate dependence. The difference observed for evaporation and sputtering was discussed based on the kinetic energy of the particles impinging on the substrate during the deposition. An appropriate orientation of the β-NaGaO2 film for ion exchange was discussed in terms of the in-plane shrinkage generated during the ion exchange from β-NaGaO2 to β-CuGaO2.
Full Paper
published : vol. 125, no.12, December 2017
Hoang Tuan TONG, Zhongchao DUAN, Dinghuan DENG, Takenobu SUZUKI and Yasutake OHISHI
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Supercontinuum (SC) generation in tellurite hybrid microstructured optical fibers (HMOFs) whose refractive index difference between core and cladding materials was as large as 0.49 was demonstrated for the first time. The fiber was successfully fabricated and its chromatic dispersion was tailored to be near-zero and flattened with three zero-dispersion wavelengths at 1270, 1973 and 3627 nm. A broad SC generation was experimentally demonstrated with 5-dB spectral flatness over a 1060-nm spectral bandwidth by using a 20-cm-long section of the fabricated tellurite HMOF.
Full Paper
published : vol. 125, no.12, December 2017
Qifu BAO, Weixia DONG, Jian-er ZHOU, Kun LIU and Tiangui ZHAO
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Porcelain ceramic tiles are low-temperature prepared by introducing multiple fluxes. The multiple flux compositions are potash feldspar-sodium feldspar-lithium porcelain stone- calcite four flux system. Effects of calcite contents on the microstructure, sintering and mechanical properties of the samples are studied in a fast firing process. The sintering behaviors of the samples are evaluated by linear shrinkage, water absorption and bulk density. The fired samples are characterized by X-ray diffraction, scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy and bending strength measurements. Well densification of the porcelain ceramic tiles is obtained at a low temperature 1130–1150°C. The sample prepared with 11% calcite exhibits higher shrinkage and bulk density, lower water absorption at a temperature of 1130°C. Higher bending strength at a composition containing at 11% calcite is due to appropriate densification and high anorthite, quartz and mullite crystallinity.
Full Paper
published : vol. 125, no.12, December 2017
Chengxiang ZHENG, Hua YANG and Ziming CUI
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Rose flower-like Bi2WO6 hierarchical architectures with average diameter of 7 µm were synthesized via a hydrothermal route. The as-synthesized Bi2WO6 hierarchical architectures were decorated with Au nanoparticles (20–110 nm in size) by a photocatalytic reduction method. The prepared samples were systematically investigated by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, electrochemical impedance spectroscopy and photocurrent response. The photocatalytic performance of the samples was evaluated by the degradation of RhB in aqueous solution under simulated sunlight irradiation. It is observed that Au–Bi2WO6 composite exhibits a photocatalytic activity much higher (about 2.7 times higher) than that of bare Bi2WO6. The enhanced photocatalytic activity of Au–Bi2WO6 can be attributed to the enhanced separation of photogenerated electron–hole pairs due to the electron migration from Bi2WO6 hierarchical architectures to Au nanoparticles. As a result, more electrons and holes are able to participate in the photocatalytic reactions. The underlying photocatalytic mechanism was discussed.
Full Paper
published : vol. 125, no.12, December 2017
Shigeo HAYASHI, Takahiro ONUMA and Fumito KAGAYA
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The fixing of electrophoretically deposited natural zeolite particles on a metal substrate by “geopolymer reaction,” i.e. the polymerization of silicate monomers in a solution to form a polymer phase that can bind particles onto solid materials, was investigated. Finely ground natural zeolite (clinoptilolite) particles were dispersed in ethanol, and deposited on a stainless-steel electrode by electrophoretic deposition (EPD) with silica sol particles and polyvinylpyrrolidone (PVP) as binder materials. The deposit was then fixed to the electrode by curing in an alkali silicate aqueous solution containing Na2SiO3 and NaOH at 40°C for 24 h. The addition of the mixed binder of silica sol and PVP to the suspension used for the EPD was effective for the fixing treatment. After the fixing treatment, the durability of the zeolite deposit in stirred water was largely enhanced. It was also found that fixed deposits treated in solutions containing a smaller amount of Na2SiO3 showed better durability. Fixed deposits, containing the starting zeolite phase, moreover, showed the adsorption property of Pb2+ ions in the aqueous solution.
Full Paper
published : vol. 125, no.12, December 2017
Jongman LEE, Jang-Hoon HA, In-Hyuck SONG and Dong Woo SHIN
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A facile surface modification technique for imposing antifouling properties on ceramic microfiltration (MF) membranes was developed based on the chemical conjugation of organosilane molecules on ceramics. The ceramic MF membranes (pore size: approximately 0.1 µm) were fabricated using conventional dip coating in an alumina slurry with nano-sized particles. The membranes were subsequently subjected to organosilane grafting with different molar concentrations (25, 50, and 100 mM). The physicochemical analysis of the organosilane-grafted membranes revealed a small decrease in pore size/roughness, which resulted from the new formation of organosilane multilayers (i.e., pore-filling effect). The pure water permeability was also diminished to some extent while exhibiting minimal influence on the permeation flux. Because of the electrostatic repulsion force between the surface-modified MF membranes and the model foulants, serious foulant adsorption followed by flux decline was significantly alleviated. In particular, the lowest organosilane concentration (25 mM) showed the greatest flux performance. This was mostly attributed to the reduced effect of pore-size restriction and electrostatic repulsion forces. We therefore achieved the optimum organosilane-grafting conditions for ceramic MF membranes, which not only minimized the alteration of surface morphology/pore size and hydraulic permeability but also remarkably improved the antifouling properties.
Full Paper
published : vol. 125, no.12, December 2017
Kazuma OIKAWA, Kei TOYOTA, Shigeaki SAKATANI, Yamato HAYASHI and Hirotsugu TAKIZAWA
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Hydrophobic silica xerogels containing trimethylsilyl (TMS) and dimethylsilyl (DMS) organic hydrophobic functional groups were synthesized using waterglass as the starting material. Five types of hydrophobic silica xerogels with varying surface coverages of the TMS and DMS groups were synthesized by changing the molecular structure of siloxane, which was used to introduce the hydrophobic moieties into the hydrogel and to investigate the resultant surface structures and thermal characteristics. The results revealed that the relative area of silica xerogels was smaller with a higher coverage of DMS groups. In addition, the thermal decomposition temperature of the silyl group shifted to higher temperatures, and the weight reduction during heating was also relatively limited in the above samples.
Full Paper
published : vol. 125, no.12, December 2017
Anongsack PASEUTH, Yasuki KIDO, Shinya IMAMURA, Kazuo YAMAGATA, Akira MIURA and Kiyoharu TADANAGA
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Al-rich cubic (c-) AlxTi1−xN (x ≈ 0.8) coating comprising self-organised c-Al(Ti)N/c-Ti(Al)N nanolamellae was prepared in a previous study by low-pressure chemical vapour deposition (LP-CVD) using an AlCl3–TiCl4–NH3–Ar–H2 precursor system. In the present study, we investigated the effects of isothermal annealing at 800 to 1200°C for 1 to 10 h on the crystal structure, microstructure, and hardness of the coating, and compared them to those of a monolithic c-AlxTi1−xN (x ≈ 0.6) coatings prepared by arc-evaporated physical vapour deposition (PVD). The X-ray diffraction patterns indicated high phase stability of the former coating up to 1200°C after 1 h. High-resolution transmission electron microscopy revealed that the nanolamellae in c-AlxTi1−xN (x ≈ 0.8) coating remained stable after post-annealing at 900°C for 5 h. The spontaneously formed coherent nanostructure suppressed diffusion in this coating, and the spinodal decomposition and hexagonal phase formation were thus shifted to higher temperatures. Consequently, age hardening in LP-CVD c-AlxTi1−xN (x ≈ 0.8) helped to maintain its hardness at up to 1100°C after 10 h. The improved thermal stability and hardness at elevated temperature of the Al-rich c-AlxTi1−xN coating by LP-CVD led to a significant improvement in the cutting tool life, by factors of 2 and 10 compared to state-of-the-art CVD- and PVD-coated inserts, respectively. These improvements in thermal stability and elevated hardness in c-AlxTi1−xN (x ≈ 0.8) coating prepared via LP-CVD process could remarkably enhance tool life for dry and high-speed cutting applications.
Technical Report
published : vol. 125, no.12, December 2017
Hirotaka MAEDA, Tomoya SATO, Matthew William ENGLAND, Atsushi HOZUMI and Toshihiro KASUGA
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Thermal properties of superhydrophilic nanocomposite films prepared from polyvinylpyrrolidone and aminopropyl-functionalized clay were studied. The films were treated at various relative humidities to absorb water. They showed excellent water-absorption properties and their capacity (amount of water absorbed from the air) was found to be markedly influenced by the relative humidity. Absorbed water into the films led to enhancement of their thermal diffusivity. Due to the large amount of absorbed water by the films after the treatment at 98%, their thermal conductive properties were considerably improved.
Note
published : vol. 125, no.12, December 2017
Jae-Young SHIN and Bong-Ki RYU
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For lead-free low-melting sealing materials, the boron oxide alkali molybdate glass system was investigated with different boron oxide contents between 0 and 8 mol %. The glasses were characterized using differential scanning calorimetry, and infrared spectroscopy, and by their dissolution rates and densities. As the boron oxide contents increase, the glasses maintain their low temperature properties (Tg under 175°C), and new network formers of [BO3] triangular units and [BO4] tetrahedral units appear. The glasses possess MoO4, MoO6, BO3 and BO4 groups as basic structural units, and existing weak Mo–O–Mo bridge bonds convert into strong Mo–O–B bridge bonds. As a result, chemical durability is improved.
Note
published : vol. 125, no.12, December 2017
Fumiyuki SHIBA, Takumi SUZUKI and Yusuke OKAWA
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One-dimensional hydroxyapatite (1D-HAP) particles were synthesized via a hydrothermal process using calcium sodium nitrilotriacetate (CaNa–NTA) as a Ca2+ reservoir. CaNa–NTA dissolved slowly at 150°C to enable Ca2+ to be supplied to the aqueous phase to react with phosphate and hydroxide ions. The average length and width of the 1D-HAP particles were 6.0 µm and 60 nm, respectively; the former depended on the amount of CaNa–NTA loaded but the latter did not. We investigated the formation of 1D-HAP particles by powder X-ray diffraction measurement and electron microscopy observation.
Express Letter
published : vol. 125, no.11, November 2017
Kotaro FUJII, Kazuho SHIMADA, Masatomo YASHIMA
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Crystal structure and electron-density distribution of the perovskite-type oxynitrides BaNbO2N and SrNbO2N have been analyzed by the synchrotron X-ray powder diffraction, Rietveld and maximum-entropy methods. In both BaNbO2N and SrNbO2N, the electron-density levels along the Nb–(O,N) bonds are significantly higher than those along the Ba–(O,N) and Sr–(O,N) bonds, which indicates higher covalency of the Nb–(O,N) bonds. The Nb–(O,N) bonds in SrNbO2N have higher electron-density levels than that in BaNbO2N, which suggests higher covalency of Nb–(O,N) bonds in SrNbO2N. The higher covalency of SrNbO2N cannot explain its wider band gap Eg than Eg of BaNbO2N. The wider Eg of SrNbO2N compared to BaNbO2N is attributable to the smaller Nb–(O,N)–Nb′ angles of SrNbO2N.
Feature: The 55th Symposium on Basic Science of Ceramics
Full Paper
published : vol. 125, no.10, October 2017
Sayaka NODA, Masanori KOSHIMIZU, Yutaka FUJIMOTO, Go OKADA, Keiichiro SAEKI, Takayuki YANAGIDA and Keisuke ASAI
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We report the properties of CsCaCl3, storage phosphors doped with Eu, Ce, or Cu. Both doped and undoped CsCaCl3 samples were synthesized as ceramics. For undoped CsCaCl3, thermally stimulated luminescence (TSL) spectrum showed a broad band around 360–390 nm, and optically stimulated luminescence (OSL) spectrum exhibited the same band with a shoulder near 320 nm. These bands were attributed to different kinds of defects or impurities. The OSL and TSL spectra of Eu-doped CsCaCl3 showed a band around 440 nm arising from the 5d–4f transition of Eu2+. The Ce-doped CsCaCl3 showed the OSL and TSL bands originating from the 5d–4f transition of Ce3+. An intense band at 345 nm appeared in the OSL spectrum of Cu-doped CsCaCl3 due to Cu+, and an additional peak at 430 nm was ascribed to Cu+ ion perturbed by OH ion. On the other hand, the TSL spectrum of Cu-doped CsCaCl3 had a peak around 470 nm and it was assigned to Cu2+. The TSL glow curves of the undoped, Eu-doped, Ce-doped, and Cu-doped CsCaCl3 were different from each other. This suggested that the dopant ions influenced the trapping process of electron–hole pairs, which were formed upon irradiation.
Feature: The 55th Symposium on Basic Science of Ceramics
Full Paper
published : vol. 125, no.10, October 2017
Akira KISHIMOTO, Koyo SHIMOYAMA, Takashi TERANISHI and Hidetaka HAYASHI
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Improving the conductivity of 8 mol % yttria-stabilized zirconia (8YSZ) electrolyte has enabled a lowering of the operating temperature of solid oxide fuel cells. We previously reported that millimeter-wave irradiation heating increases the ionic conductivity of ceramics. The ionic conductivity of 8YSZ under millimeter-wave irradiation heating had been up to 20 times higher than that with conventional heating. In the present study, we investigated the optimal thermal environment for millimeter-wave irradiation heating. We also investigated the thermal profile of samples under millimeter-wave irradiation heating to elucidate the rate of the non-thermal effect.
Feature: The 55th Symposium on Basic Science of Ceramics
Full Paper
published : vol. 125, no.10, October 2017
Naoyuki KITAMURA
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Uniaxial-compression creep test and dynamic viscoelastic measurement were performed on binary sodium- and lithium-silicate glasses at around their deformation temperature. The derived creep function was converted into a relaxation modulus using the Laplace transformation and its inversion. Shear relaxation modulus G(t) was expressed by a 1-term Maxwell model for both glass systems. In the sodium system, the viscous term in the model decreased with increasing modifying oxide. In contrast, the lithium system showed a higher value in the elastic term and a lower value in the viscous term than the sodium system. The storage elastic modulus E′(ω) observed in the dynamic measurement started to decrease at the glass transition temperatures, and complicated fluctuation of the modulus was observed at around the deformation temperatures for frequencies larger than a few Hz. The decrease in the modulus at the transition temperature has been suggested to originate from slipping between silicate clusters which were separated by non-bridging oxygen with the modifying cations similar to polymer materials. The master curve of the loss elastic modulus E′′(ω) showed unique frequency dependence in all sodium-silicate glasses, while the data at high frequencies at around the deformation temperature deviated from the curve. This suggested that slipping between silicate clusters is the main process of structural relaxation, and anomalies in the dynamic modulus at around the deformation temperature could be related to other relaxation. The E′(ω) of the lithium-silicate glass showed similar temperature dependence and the master curve of E′′(ω) had a narrower frequency distribution. The contribution to E′′(ω) below 10−2 Hz was smaller than in the sodium system. This lack of slow relaxation was well consistent with the comparably lower viscous term of G(t) in the Maxwell model. Injection testing into a narrow pore showed a faster saturation of the injected volume for the lithium-silicate glass.
Feature: The 55th Symposium on Basic Science of Ceramics
Full Paper
published : vol. 125, no.10, October 2017
Fumitake OKABE, Chinami MOCHIZUKI, Takahiro TAKEI, Sayaka YANAGIDA, Akira MIURA and Nobuhiro KUMADA
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Mesoporous silica-phosphate hybrids were successfully prepared by three processes: hybridization post synthesis by H3PO4, hybridizations during synthesis by Na2HPO4 and by PO(OC2H5). X-ray diffraction patterns confirm that the hexagonal pore structure was maintained after the hybridization process. The maximum phosphate amount was 2.9 mol % in the sample prepared by hybridization during synthesis from Na2SiO3 and PO(OC2H5)3. The specific surface area showed a large value of approximately 1000 m2/g despite the hybridization. The Si–O–P bonds were confirmed by nuclear magnetic resonance and X-ray photoelectron spectroscopy. The maximum adsorption amount of rare earth metal cations into the hybrid was approximately 70% of the initial concentration (50 mg/L) for each rare earth metal cation in coexistence with 13 rare earth metal cations.
Feature: The 55th Symposium on Basic Science of Ceramics
Full Paper
published : vol. 125, no.10, October 2017
Fumiya SATO, Hitoshi SHIOKAI, Yusuke YANO, Masatoshi SUGIURA and Ryoji TAKAHASHI
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Rare earth hydroxide nitrates are prepared from rare earth nitrates by hydrothermal treatment. Three crystal phases, M(OH)3 (M1), M2(OH)5.14(NO3)0.86·H2O (M2), and M4O(OH)9NO3 (M4) are identified. The crystal phase systematically changes from M1 to M4 through M2 with decreasing radius of rare earth cation. Morphology of nanocrystal depends on the crystal phase. M1 and M4 phases grow to be nanorod, and M2 to nanoplate.
Feature: The 55th Symposium on Basic Science of Ceramics
Full Paper
published : vol. 125, no.10, October 2017
Ryoji TAKAHASHI, Akiko ONISHI, Fumiya SATO and Makoto KURAMOTO
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Bimodal porous alumina was prepared from the solution with aluminum chloride and 1,2-propylene oxide by adding propylene glycol oligomers (PPG). Because of hydrophobic nature of PPG, the addition of PPG induces phase separation during sol–gel reaction, and macroporous morphologies are formed by fixing transitional structure of phase separation. Since ethanol works as a co-solvent, the macropore size of the obtained gel can be increased by decreasing ethanol content. Change in the concentration of other constituents such as PPG has also an effect to control morphologies through changing the timing of phase separation and sol–gel transition.
Feature: The 55th Symposium on Basic Science of Ceramics
Full Paper
published : vol. 125, no.10, October 2017
Yuma MITANI, Takahiro TAKEI, Sayaka YANAGIDA and Nobuhiro KUMADA
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Cr-based layered double hydroxides (LDHs) containing Ni, Zn, or Cu as the divalent cation were prepared with a divalent-to-trivalent cation molar ratio of 3. Then, LDH hybrids intercalated with polyanions ([PMo12O40]3−(PMoO) or [H2W12O42]10− (HWO)) were prepared by ion exchange and hydrothermal processes. The shift of the diffraction line indicating interlayer space in the X-ray diffraction patterns confirmed the intercalation in the LDH. The fraction of PMoO and HWO anions incorporated was 30–70 or 60–90% of ion exchange capacity, respectively, by charge compensation for Cr3+. In the conversion of styrene by epoxidation and oxidation, the hybrid of the LDH composed of Zn and Cr with PMoO showed the maximum catalytic activity, with 70% conversion. For the LDH composed of Ni and Cr, hybridization with a polyanion enhanced the catalytic behavior by a synergistic effect resulting from the basicity of the LDH phase.
Feature: The 55th Symposium on Basic Science of Ceramics
Full Paper
published : vol. 125, no.10, October 2017
Norio SAITO, Pierric LEMOINE, Stéphane CORDIER, Takeo OHSAWA, Yoshiki WADA, Fabien GRASSET, Jeffrey Scott CROSS and Naoki OHASHI
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The electronic and structural characteristics of the octahedral molybdenum cluster-based ternary compound, Cs2[Mo6Cl14], were investigated based on density functional theory (DFT) and subsequent comparisons with experimentally observed results. The geometry optimization and band structure calculations of Cs2[Mo6Cl14] were performed using three standard functionals: local density approximation, Perdew-Burke-Ernzerhof (PBE) as a generalized gradient approximation, and PBE revised for solid compounds (PBEsol). The validity of the calculated results was experimentally examined via X-ray powder diffraction, ultraviolet–visible (UV–vis) diffuse reflection, and X-ray photoemission spectra (XPS) measurements. PBEsol was found to show the best performance in terms of reproducing the experimentally refined lattice structure of the compound. The calculated band gap energy (Eg) was consistent with the value evaluated from the UV–vis measurement. Furthermore, the XPS valence spectrum of the compound was well reproduced by the calculated projected density of state weighted with the photoionization probabilities of Al Kα. Although the spectral shapes simulated using the three functionals were similar, PBEsol reproduced the energy levels of the electronic states of both [Mo6Cl14]2− and Cs+ ion with greater consistency. Therefore, it was concluded that PBEsol is the most appropriate functional for DFT calculations of the metal cluster-based lattice system.
Feature: The 55th Symposium on Basic Science of Ceramics
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published : vol. 125, no.10, October 2017
Go SAJIKI, Yasuhiko BENINO, Chinatsu OKI, Koji OHARA, Hiroshi OKANO and Tokuro NANBA
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Structural analyses of niobium oxide (NbOx) amorphous film prepared with a sputtering method have been performed by using synchrotron X-ray radiation at SPring-8. The composition was determined as Nb2O5·0.8H2O from the measurements of Rutherford back scattering, X-ray fluorescence, X-ray absorption near edge structure, and thermal desorption spectroscopy. Structural information was obtained by extended X-ray absorption fine structure and high energy X-ray diffraction measurements. It was supposed from the experimental data that NbOx consisted of distorted NbOn polyhedra connected by corner- and edge-sharing. Structural models were constructed with reverse Monte Carlo (RMC) simulations. In the RMC models, the structural characteristics were successfully reproduced, and H atoms were, however, randomly distributed. Then, bond valence sum (BVS) constraint was introduced to the RMC simulation. As the results, narrower distribution in BVS was achieved for all the constituent atoms, and distinct OH bonds were effectively generated in the RMC model.
Feature: The 55th Symposium on Basic Science of Ceramics
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published : vol. 125, no.10, October 2017
Yutaka FUJIMOTO, Takayuki YANAGIDA, Masanori KOSHIMIZU and Keisuke ASAI
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In this study, we report on the optical and thermolumienscence (TL) properties of newly developed (30 − x)Li2O–20Al2O3–50B2O3–2xCeO2 (values are in mol %) glass dosimeters prepared by a conventional melt quenching method. The optical absorption spectra showed broad absorption band in the 200–370 nm wavelength with Ce-doping. The photoluminescence (PL) band appeared near the wavelength of 365 nm under excitation at 240, 270, and 315 nm, which is due to the transition from 5d excited states to 4f (2F5/2, 2F7/2) ground states of Ce3+. In the TL glow curve measurements, the Ce-doped glasses exhibited a dominant glow peak in the 370–425 K temperature range. The 0.5 cat% Ce-doped glass (x = 0.5) showed the highest TL intensities in our prepared glasses. The 5d–4f (2F5/2, 2F7/2) emission band of Ce3+ also appeared in the 365 nm wavelength range in the TL spectrum. TL response in the dynamic range was confirmed using the 0.5 cat% Ce-doped glass over 10−3–102 Gy X-ray dose.
Feature: The 55th Symposium on Basic Science of Ceramics
Note
published : vol. 125, no.10, October 2017
Kenji SHINOZAKI, Ryosuke KAMAKURA, Shunsuke MURAI, Toshiyuki MIHARA, Naoyuki KITAMURA, Yuki KAWACHIYA, Katsuhisa TANAKA and Tomoko AKAI
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We demonstrated that a moth-eye surface pattern on the luminous inorganic glass could enhance the photoluminescence (PL) intensity notably. A moth-eye pattern of a square array of cones at pitch of 250 nm was fabricated on Eu3+-doped MgF2–MgO–BaO–B2O3 glass by thermal nanoimprinting at 520°C. A simulation with rigorous coupled-wave analysis demonstrated that the surface structure could reduce the surface reflectance in the optical input for the excitation wavelength λ of 405 nm, i.e., −1.1% for p-polarized light, 10.6% for s-polarized light, and 4.1% for non-polarized light in total of a half round angle for the irradiation from a surface light source. The angularly dependent PL of the excitation angle on the nanoimprinted glass was measured by an excitation of UV laser diode (λ = 405 nm). The enhancements of ∼0% for p-polarized light and ∼9% for s-polarized light were observed at the incident angle = 5°.
Feature: The 55th Symposium on Basic Science of Ceramics
Note
published : vol. 125, no.10, October 2017
Satoshi HINOKUMA, Yusuke KAWABATA, Saaya KIRITOSHI, Shun MATSUKI and Masato MACHIDA
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Local structures around copper oxides (CuOx) supported on aluminum oxide borates (10A2B) during the NH3 combustion reaction were studied by operando XAFS. Although CuOx in as-prepared CuOx/10A2B at room temperature can be assigned to CuO, the CuO was partly reduced to Cu2O during NH3 combustion at 400°C. In contrast, CuAl2O4 was formed after thermal aging of CuOx/10A2B at 900°C for 100 h in air, local structures of which were preserved during NH3 combustion at 600°C.
Feature: The 55th Symposium on Basic Science of Ceramics
Note
published : vol. 125, no.10, October 2017
Naoyoshi NUNOTANI, Naoki MORIYAMA, Kenji MATSUO and Nobuhito IMANAKA
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A novel PdO/La10Si6O27/γ-Al2O3 catalyst was developed in order to decompose methane. In this catalyst, we selected the oxide-ion-conducting La10Si6O27 solid with an apatite-type structure as a promoter to facilitate the supply of active oxygen to the PdO activator. For the comparison with PdO/La2O3/γ-Al2O3, where La2O3 is a simple rare earth sesquioxide, the catalytic activity of PdO/La10Si6O27/γ-Al2O3 was higher than that of PdO/La2O3/γ-Al2O3, regardless of their same surface area. Since La10Si6O27 exhibited two orders of magnitude higher conductivity than La2O3, the high oxide-ion-conducting property of La10Si6O27 might facilitate the oxidation of methane by supplying active oxygen from inside the lattice.
Feature: The 55th Symposium on Basic Science of Ceramics
Note
published : vol. 125, no.10, October 2017
Isuru WITHANAGE, Nobuhiro KUMADA, Takahiro TAKEI, Sayaka YANAGIDA, Yoshihiro KUROIWA and Chikako MORIYOSHI
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Pyrochlore-type (K0.73H0.27)NbO3·1.72H2O and (K0.56H0.44)TaO3·1.14H2O were synthesized by a hydrothermal reaction. The K+ ions in these compounds were reacted with Ag+ ions in excess molten AgNO3 at 300°C. This reaction produced fluorite-type Ag0.41Nb0.59O1.68 and pyrochlore-type Ag0.93TaO2.97·0.94H2O. Their crystal structures were refined by the Rietveld method using synchrotron X-ray powder diffraction data. Only the pyrochlore-type Ag0.93TaO2.97·0.94H2O exhibited photocatalytic activity toward phenol degradation under UV light irradiation.
Full Paper
published : vol. 125, no.10, October 2017
Geun-Hyoung LEE
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One dimensional rod-shaped and two dimensional twin-crystal shaped ZnO crystals were fabricated by thermal evaporation of a mixture of ZnS and graphite powders in air at atmospheric pressure. Twin-crystal shaped ZnO crystals were formed at 1050°C, while rod-shaped ZnO crystals were synthesized at 1150°C. The morphology of ZnO crystals was drastically changed according to the growth temperature. It is particularly interesting that two hexagonal plates formed a twin crystal, in which hexagonal shaped ZnO plates were symmetrically grown on both sides of a mirror-like plane. The twin crystal looked like a yo-yo. X-ray diffraction analysis showed that the rod and twin-crystal shaped ZnO crystals exhibited a wurtzite crystallographic structure. A strong green emission peak at 500 nm was observed in the cathodoluminescence spectra of the ZnO crystals at room temperature.
Full Paper
published : vol. 125, no.10, October 2017
Naoya IWATA and Takamasa MORI
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Suspension spraying is a promising surface modification technique, because finer particles can be used in contrast to the case of conventional thermal spraying. However, the optimal conditions for preparing suitable suspensions have not yet been established. Thus, the effects of particle dispersion and flocculation states on the properties of suspension-sprayed coatings were examined in the present study. Y2O3 suspensions were prepared using various quantities of the dispersant. The flow curves and gravitational settling behaviors of the prepared suspensions were investigated. The amounts of the dispersant adsorbed on the particles were also determined. In addition, Y2O3 coatings were fabricated using suspension spraying, and the properties of the obtained coatings were investigated. The addition of the dispersant affected the suspension flow characteristics, because the amount of the dispersant adsorbed increased with increasing dispersant concentration. Furthermore, the coating characteristics improved as the apparent viscosity of the suspension decreased.
Note
published : vol. 125, no.10, October 2017
Liangbiao WANG, Wanjun XI, Tao MEI, Yibing CAI, Juanjuan LU, Dejian ZHAO, Hongying HUANG, Weiqiao LIU and Quanfa ZHOU
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Usually, the synthetic process of hafnium carbide (HfC) by using hafnium dioxide as hafnium source requires high reaction temperature. In this study, we have successfully synthesized HfC nanoparticles by a solid state reaction of hafnium dioxide, lithium carbonate and metallic magnesium in a stainless-steel autoclave at 700°C for 10 h. The X-ray powder diffraction pattern reveals that the obtained sample is cubic phase HfC with lattice constant of a = 4.633 Å. Scanning electron microscope images show that the obtained HfC sample is composed of uniform particles with an average size of about 10 nm. Furthermore, the formation mechanism and oxidation resistance of the HfC nanoparticles have been investigated.
Technical Report
published : vol. 125, no.3, March 2017
Hironobu ABIKO
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Silica gel is commonly used as a sampling agent in small glass tube products for work environment measurements of organic solvent vapor, as established by the Industrial Safety and Health Act in Japan. However, to date there has been no national standard for sampling tube products, and the extraction efficiency of adsorbed organic solvent vapor from silica gel significantly affects the accuracy of measurement. Here, we have investigated the material properties of silica gel used in typical Japanese sampling tube products, and the effects on the efficiency as determined by the phase equilibrium method. This study focused particularly on specific surface area, porosity and grain diameter of silica gel specimens.

Special Call for Papers

Specially Scheduled Issue “the 56th Symposium on Basic Science of Ceramics”PDF
Posted Deadline:March 31, 2018
Posted schedule No.:2018. October issue