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Feature: The Second Young Professional Forum (YPF) in PACRIM 13
Review
published : vol. 128, no.7, July 2020
Duo YU, Jie YIN, Buhao ZHANG, Xuejian LIU and Zhengren HUANG
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The high-entropy carbides (HECs) are reviewed in terms of the crystal structure, powder synthesis, densification, and mechanisms in this article. The inter-diffusion rate of binary carbide is mainly analyzed and predicted based on lattice parameters. During the solid solution formation progress, the densification methods usually adopted were hot pressing and spark plasma sintering. It was found that the distribution of metal atoms was more uniform in high-entropy powders derived from binary carbide raw materials. HECs displayed higher hardness, elastic modulus, and oxidation resistance, and meanwhile exhibited lower thermal conductivity compared to binary carbides. HECs are expected to be used as high-speed atmospheric re-entry vehicles.
Feature: The Second Young Professional Forum (YPF) in PACRIM 13
Full Paper
published : vol. 128, no.7, July 2020
Akira MIURA, Sho ISHIYAMA, Daiju KUBO, Nataly Carolina ROSERO-NAVARRO and Kiyoharu TADANAGA
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A high-entropy layered hydroxide (HELH), in which Mg2+, Al3+, Co2+, Ni2+, Zn2+ were homogeneously distributed on two dimensions sheets, was synthesized for the first time. The HELH shows moderate thermal stability and hydroxide ion conductivity up to 10−3 S cm−1. This finding presents tremendous opportunities for emerging new two-dimensional high-entropy materials.
The 74th CerSJ Awards for Academic Achievements in Ceramic Science and Technology: Review
Special Article
published : vol. 128, no.7, July 2020
Satoshi YOSHIDA
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The indentation test using a sharp diamond indenter, such as a Vickers indenter, has been long employed for comparing mechanical properties among various glass compositions, because of its simple procedure and easy operation. However, mechanisms of permanent deformation and crack nucleation in glass are far from simple. This has made it difficult to understand what controls the threshold load for cracking in a certain glass during indentation. In this review, the author’s works on indentation-induced deformation and cracking in glass are introduced, and relevant issues on the indentation technique are discussed. Especially, it is pointed out that permanent densification of glass under the indenter is a key phenomenon which controls the following cracking event. Further, it is also shown that the micro-photoelastic observation system, by which the indentation-induced stress field can be visualized, and the indentation microscope, which enables one to measure the contact area between glass and the indenter, are powerful tools to stimulate new and fresh ideas for improving mechanical properties of glass.
The 74th CerSJ Awards for Advancements in Ceramic Science and Technology: Review
Special Article
published : vol. 128, no.7, July 2020
Sungho LEE
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Glasses can be systematically designed according to their composition, and their potential to release ions can also be manipulated by tailoring their structures. Notably, phosphate invert glasses (PIG) can contain various elements that are comparable with silicate glasses due to their acidity. In this review article, novel PIGs containing therapeutic ions for bone regeneration, and anisotropic scaffolds for reconstructing bone quality were reviewed. PIGs have been structurally designed to utilize intermediate oxides, such as TiO2, Nb2O5, ZnO, and MgO. As a result, PIGs with excellent chemical durability are expected to sustain their ion-relesability for bone regeneration and exhibit antibacterial activities. In contrast, PIGs have been designed with improved ion-releasing rates, with some releasing 20 times more ions compared to conventional PIGs. This was accomplished by manipulating the glass structure to contain only orthophosphates and orthosilicates. In other words, these glasses have no long-chain structures. Therefore, such glasses can be carriers of therapeutic ions for composite biomaterials, and are expected to enhance bone regeneration. Fibrous anisotropic scaffolds containing the designed glass have also been developed for the simultaneous reconstruction of bone quantity and quality. These scaffolds were enhanced to encourage bone formation by releasing ions from the glass, which controlled bone quality by direction of the calcified tissue in a single direction. Therefore, PIGs are expected to expand into various biomedical fields, as they can be tailored to have different properties according to their glass network structure.
Full Paper
published : vol. 128, no.7, July 2020
Pei-Ru ZHOU, Xin HE, Feng ZHU and Xiao-Qing ZHAO
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The effect of cellulose nanofibrils (CNFs) on the mechanical properties of substrate of metal ceramic heater and electrical properties of electrically conductive layer were studied experimentally in a tube furnace at 1600 °C under reduced atmosphere. The alumina ceramics with 96 wt % of alumina and 4 wt % of sintering additives, namely SiO2 and MgO were applied as the substrate. There was a noticeable rise in fracture toughness of alumina ceramics. The addition of 3 wt % of CNFs in ceramic had a significant effect on the improvement of fracture toughness. A KIC of 6.52 MPa·m1/2 was achieved through the addition of 3 wt % CNFs. A considerable decrease in KIC was observed with addition beyond 3 wt % of CNFs. On the other hand, the relative density and bending strength had been steadily dropping with addition of CNFs. The bending strength was 296 MPa with no addition of CNFs. The bending strength of only 158 MPa was achieved with the addition of 5 wt % of CNFs. The sample with 1 wt % CNFs was selected as the substrate. The SiO2 in the ceramic was reduced by pyrolysis of CNFs and formed W–Si solid solution. The temperature coefficient of resistance was decreased by the solution of Si into W.
Full Paper
published : vol. 128, no.7, July 2020
Toru SEKIYA, Takahiro YAMADA and Hisanori YAMANE
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Agglomerates of faceted single crystal grains of titanium nitride (TiN) with a size of 1–100 µm were synthesized by heating TiO2, FeTiO3, or TiO and Na in a boron nitride (BN) crucible at 1000–1100 °C under an argon atmosphere. Water soluble sodium borates were also produced as a melt phase during the heating. The yield of TiN prepared from TiO2 at 1100 °C was 77%. Wavelength-dispersive X-ray analysis of the TiN single crystal grains revealed that the composition was almost stoichiometric, and the oxygen content was less than 1.2 at %. The TiN formation could be regarded as a sort of metathesis reaction, in which the oxygen of TiO2 and the nitrogen of BN were exchanged.
Full Paper
published : vol. 128, no.7, July 2020
Maoqi JU, Yonghe LIANG, Saisai LI, Manfei CAI, Jianhua NIE and Zhilin SHAN
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This work addresses the evaluation of different spinel-containing composition sagger material in thermo-mechanical properties and corrosion resistance contacting with cathode material. In order to improve the corrosion resistance, the efficient way is to prevent the Li+ diffusion into the sagger material, LiAlO2 generated by the reaction between spinel and Li-ion battery cathode material wrapped on the surface as corrosion protective layer during the calcination, which prevent the physically contact and react with cathode materials, due to the LiAlO2 obtained the low-activity to react with cathode material. Meanwhile, the thermo-mechanical properties of sagger material with different addition of spinel were characterized. The results indicated that the using of spinel lead to the better mechanical strength and thermal shock resistance of the sagger material due to introducing the second phase and mismatch of thermal expansion, respectively. Considering all the aspects, the optimal addition of spinel was 14 wt %.
Full Paper
published : vol. 128, no.7, July 2020
Koji KAWADA, Kimihiro YAMASHITA and Toshinori OKURA
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This study has focused on the effect of Si-substitution with alio-valent boron and phosphorus on sodium-ion (Na+) conduction properties of the newly developed glass-ceramic Na5FeSi4O12. The glass-ceramics with the Na+ conducting single phase were obtained with the compositions Na5+xFeBxSi4−xO12 and Na5−yFePySi4−yO12, although the solubility limits were restricted as x < 0.4 and y < 0.3. The conductivity of the mother Na5FeSi4O12 glass-ceramics was enhanced on both Na5+xFeBxSi4−xO12 and Na5−yFePySi4−yO12, and the maximum conductivities were achieved on the compositions Na5.2FeB0.2Si3.8O12 (x = 0.2) and Na4.9FeP0.1Si3.9O12 (y = 0.1), as high as 3.1 × 10−3 and 4.2 × 10−3 S cm−1 at 300 °C, respectively.
Full Paper
published : vol. 128, no.7, July 2020
Kazuki TAJIMA, Hiroshi WATANABE, Mizuka NISHINO and Tohru KAWAMOTO
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Tungsten trioxide (WO3) undergoes an electrochromic (EC) color change upon ion exchange via electrochemical redox reactions. Thin films of WO3 are often fabricated by physical processes based on magnetron sputtering, and lithium is typically used as the cationic species that causes the color change. In a preliminary study, we achieved a suitable EC performance by using potassium as the cation in wet-processed films manufactured by a spin-coating method using WO3 nanoparticles. However, comparisons of the EC properties of the WO3 thin films prepared by various techniques are insufficient, and the behavior of potassium in these systems remains unclear. In this study, we observed that it was difficult for potassium to be swept smoothly into films prepared by sputtering or ion plating. In contrast, a wet-processed thin film obtained by spin coating was found to exhibit a good EC performance. This appeared to be largely attributable to structural variations arising from the film preparation methods.
Full Paper
published : vol. 128, no.7, July 2020
Guo-Rui LI, Chen-Hui LI, Jiang-An LIU, Yang ZOU, Liang HU and Yu-Sheng SHI
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The foamed alumina ceramics with excellent sound absorption performance especially at low frequency were fabricated by gelcasting-foaming process which gelled at room temperature. This process was simpler and more environmental-friendly than conventional gelcasting process because only a very small amount of organics were used and then green bodies could be sintered directly without binder removal process. The effects of foaming agent on porosity, pore size, compressive strength and sound absorption characteristics of the porous ceramics with different air-gap depths were discussed. The results showed that with the increasing of foaming agent content from 0.10 to 0.25 wt %, the porous ceramics had higher porosity, larger pore size, smaller compressive strength and better sound absorption characteristics. But the foaming agent’s effect got less significant than before when it’s amount was more than 0.25 wt %. The sound absorption peak of foamed ceramics shifted towards higher frequency as increasing foaming agent content, but it shifted towards lower frequency as increasing the air-gap depth. And within the data range of this study, increasing porosity could improve the sound absorption characteristic of the ceramics with an air gap. The ceramic with foaming agent content of 0.25 wt % and air-gap depth of 80 mm had the best sound absorption whose maximum sound absorption coefficient and noise reduction coefficient is 0.99 at 400 Hz and 0.79 respectively, and its mean sound absorption coefficient at 50–1000 Hz is ∼0.6.
Full Paper
published : vol. 128, no.7, July 2020
Yujing WANG, Junnan HAN, Jiexiu ZHAI and Daling YANG
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Due to the unique three-dimensional spatial network structure formed by SiO2 nanoparticles and high surface aera, silica aerogel is a high-profile material in many fields. In the present study, by adopting the industrial water glass as the silicon source, silica aerogels had been prepared via the sol–gel approach followed by the ambient pressure drying process. The effects of different alkaline catalysts in terms of LiOH, NaOH, KOH, and NH3·H2O on the formation of silica aerogels were investigated. It was found that with the introduction of alkaline catalysts, the gel aging time dramatically decreased from 5840 to 31 min during the sol–gel process. Compared with the silica aerogels prepared without any catalyst, accordingly, the thermal stability was significantly improved, and the decomposition temperature increased from 375 to above 410 °C. Furthermore, the silica aerogels prepared with alkaline catalysts were featured in a distinctive double-pore structure. It was shown that the alkali metal ions might have an alkaline dissolution effect in the weakly acidic environment during the sol–gel process. Moreover, this effect might increase the contact area between different SiO2 nanoparticles, which was benefit to maintain the three-dimensional spatial network structure and resulted in the silica aerogels with higher thermal stability. The alkaline dissolution effect had an influence on the pore size distribution of silica aerogels with a double pore structure at 1.7 and 32 nm as well as retained large pore volume at about 2.60–3.35 cm3/g.
Full Paper
published : vol. 128, no.7, July 2020
Junhong ZHANG, Zhijun HE, Chen TIAN, Qing GUO, Guojian HU and Wenlong ZHAN
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In this paper, the influence of different microwave conditions on industrial waste residue was studied. It is hoped that the porous ceramic materials which can absorb SO2 and NOx in flue gas efficiently can be prepared by using these industrial waste residues. The results show that microwave treatment can effectively improve the activity of industrial waste residue and the adsorption capacity of flue gas. And the appropriate microwave sintering power and sintering time can improve the specific surface area and pore size of adsorbent, and enhance the adsorption capacity of flue gas. Under the experimental conditions, the best microwave sintering conditions are sintering power 1000 W and sintering time 1200 s. Under these conditions, the porous ceramic adsorbent has the best adsorption effect, with the desulfurization rate of 98.8% and the denitration rate of 91.9%.
Full Paper
published : vol. 128, no.7, July 2020
Fuya SUGIYAMA and Shinji IWAMOTO
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Zirconia particles were prepared by thermal treatment of zirconium(IV) tetra-n-propoxide (ZNP) in C2–C6 glycols (Glycothermal method) at 300 °C and morphology and pore structures of the products were examined. X-ray diffraction results revealed that nanocrystals of tetragonal zirconia phase were mainly obtained in all cases. However, the morphology and pore structures of the products were quite different depending on the glycols used. The products prepared in 1,4-butanediol (1,4-BG) were spherical particles with ca. 5 µm size while aggregations of fine particles were observed for other glycols. The samples obtained in 1,4-BG had large surface areas and showed narrow pore-size distributions in the mesopore region. To investigate the formation process of the products having such a unique morphology and pore system, the mixtures of ZNP and glycols were heated at lower temperatures. It was found that the thermal reaction of ZNP in 1,4-BG at 200 °C afforded intermediates with layered structures, which subsequently changed into nanocrystalline ZrO2 at elevated temperatures. These stepwise crystallization processes attribute to the unique morphology and pore system of the products obtained by the thermal treatment of ZNP in 1,4-BG.
Technical Report
published : vol. 128, no.7, July 2020
Zikri NOER, Timbangen SEMBIRING, Kerista SEBAYANG, Muhammad Noer NASRUDDIN, Rifki SEPTAWENDAR and Bambang SUNENDAR
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In this study, the effects of atmosphere firing and pre-heating treatment on the characteristics of sodium titanates were investigated. The materials were successfully prepared from titanium tetraisopropoxide-sodium chloride (TTIP-NaCl) precursors assisted by organic templates (ethylene glycol and citric acid) via facile templating and hydrothermal methods. Sodium titanates were initially prepared by mixing a sodium precursor solution with a titanium precursor solution at a stoichiometric mole ratio of 1.6:1 under vigorous stirring. This was followed by pre-heating treatment via a hydrothermal method at 150 °C for 6 h and then calcination at 800 °C for 1 h in two different atmospheres including reduction and oxidation conditions. The same process was carried out in the synthesis of the other samples without the preheating treatment. The thermal behaviors of all the as-synthesized samples were evaluated. Meanwhile, the mineralogy and microstructures of all calcined samples were investigated. Both atmosphere firing and pre-heating treatment influenced the thermal behaviors of the as-synthesized sodium titanates, resulting in various sodium titanate types with different microstructures. To prepare the sodium titanates from TTIP-NaCl precursors, the pre-heating treatment and the reduction firing seemed to be the optimum conditions for the formation of sodium titanate, in order to produce Na2Ti6O13-type sodium titanates with rod-like particles in nanometer sizes.
Note
published : vol. 128, no.7, July 2020
Masataka KINOSHITA, Teruhisa HONGO, Yoshio MATSUI and Atsushi YAMAZAKI
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Manganese oxide particles were prepared by alkaline treatment of the manganese and silicon compound. Silicon was selectively dissolved by the alkaline treatment, forming an aggregate structure of plate-like particles. Consequently, owing to the high specific surface area and surface exposure of the manganese, the catalyst exhibited excellent behavior in the oxidative decomposition of benzene.
Note
published : vol. 128, no.7, July 2020
Yoshiteru ITAGAKI, Eri SARUMARU and Hiromichi AONO
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Potentiometric sensors aiming at detecting H2 were examined. Yttria-stabilized zirconia (YSZ) based sensor elements, H2, Pt/YSZ/Pt, air, responded to a ppm level of H2 contamination in air with the value of electromotive force (ΔEMF) = 30 mV at 350 °C. Coating the Pt sensing electrode with a powder of hexagonal boron nitride (h-BN) increased the EMF response, and the sensor response further increased by the milling treatment of the h-BN powder in ethanol. However milling treatment over 24 h reversed the response to decreasing. The specific surface area of the h-BN powder monotonously increased by the ball-milling which induced exfoliation of the BN layer. While Fourier transform infrared spectroscopy analysis suggested that point defects existing in the BN plane react with ethanol or water by the milling for >48 h. It was concluded that the point defects in h-BN play a decisive role in the property of the h-BN auxiliary phase in sensor response to H2.
Technical Report
published : vol. 128, no.7, July 2020
Chihiro SAKAI and Ryoji SATO
Full Paper
published : vol. 128, no.6, June 2020
Bingyang MA, Zixian TAN, Xiaoben QI, Rongbin LI, Geyang LI and Hailong SHANG
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This paper proposed a kind of Aluminum (Al) foil filler with sputtering Ni/Al double layers on surface and a brazing method of elevating temperature. Results showed that this coated foil filler could make Al2O3 film on aluminum surface broken and sweep them into brazing seam because it was buried by Ni/Al double layer. The direct brazing of Al alloy to Al2O3 could be realized without interface reaction transition layer. Rising brazing temperature could enhance the interface between seam and ceramic, making joint fracture transfer from the interface into seam gradually. The shear strength of joint was improved to the maximum of 158 MPa at above 840 °C from 49 MPa at 680 °C.
Full Paper
published : vol. 128, no.6, June 2020
Youngjin KWON and Youngbae HAN
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The high energy density of hydrogen, in addition to its convenience for transportation and infinite resource base, make it a promising energy carrier. Solid oxide fuel cells (SOFCs), in particular—which utilize the oxidation of hydrogen at high temperatures to generate electricity—have been studied widely because of their high efficiency and relatively low cost. However, the lack of a suitable mass production method currently precludes the commercialization of SOFCs. To address this, we herein evaluate tape-casting as a means to reduce the cost of SOFC mass production. A simple de-airing technique is used to simplify the production process and an electrolyte-supported SOFC is produced without employing a buffer or functional layers. The rheological properties of green tape slurries are explored to improve tape completeness and electrolyte performance. Electrolyte conductivity is measured for a fabricated half-cell; the fine structural details are analyzed via scanning electron microscopy. As a result, a unit cell with an open-circuit voltage of 1.05 V and an electric power density of 0.476 W cm−2 at 800 °C was fabricated.
Full Paper
published : vol. 128, no.6, June 2020
Masashi MAEDA and Hiromi NAKANO
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In the Li2O–Ta2O5–TiO2 system, Li1+xyTa1−x−3yTix+4yO3 (0.14 ≤ x ≤ 0.175, 0.04 ≤ y ≤ 0.175) forms a superstructure by periodical insertion of an intergrowth layer in a matrix having a trigonal structure. In this study, to apply this unique structure as a host material of phosphor, new phosphors with a red emission color were synthesized by doping Mn4+ ion. The phosphor emitted at around 685 nm excited by 493 nm. The photoluminescence (PL) intensity closely related to the ratio of Mn4+/Mn3+ ion because the ratio changed by sintering temperature and/or Ti content in the matrix. The relationship between PL intensity and crystal structure was investigated using X-ray diffraction, a transmission electron microscope, and X-ray absorption fine structure.
Full Paper
published : vol. 128, no.6, June 2020
Waramon LANGLAR, Areeya AEIMBHU, Pichet LIMSUWAN and Chesta RUTTANAPUN
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In this paper, the synthesis of C12A7 nanopowders with OH specie inside cage via biological method using Aloe Vera (A. vera) leaf extract with different concentrations of 0, 15, 20, 25 and 50%, and microwave-assisted synthesis was reported. The effects of A. vera leaf extract concentration on the structure, morphology and specific surface area of C12A7 nanopowders were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy and N2 gas adsorption–desorption isotherm, respectively. The functional groups of C12A7 nanopowders with OH specie inside cage were analyzed by fourier transform infrared spectroscopy (FT-IR). The XRD patterns showed that the pure peak of C12A7 was obtained from the samples prepared with A. vera leaf extract concentration of 20% and above. The minimum crystallite size of the C12A7 nanopowders was found to be 43.17 nm for the sample prepared with 25% A. vera leaf extract concentration. The maximum specific surface area (SBET) obtained from N2 gas adsorption–desorption isotherm was found to be 17.25 m2/g with a minimum pore size of 12.24 nm for the sample prepared with 25% A. vera leaf extract concentration. The FT-IR spectra of C12A7 prepared with A. vera leaf extract reveals the presence of amide of protein in A. vera leaf bonded to C12A7 indicating the biological responsibility for the synthesis of C12A7. Furthermore, in this work with the microwave-assisted synthesis of C12A7 nanopowders, the calcining time could be reduced by 10 h compared with a chemical process and temperature could be reduced to 900 °C compared with a standard sintering temperature.
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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