Feature: Advanced Ceramic Science and Technology in the Western Pacific Rim Area: Reviews
Feature: Advanced Ceramic Science and Technology in the Western Pacific Rim Area: Papers
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Dong-Yeol YANG, Duk Yong YOON, Suk-Joong L. KANG
2012 Volume 120 Issue 1407 Pages
467-472
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
JOURNAL
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Widely employed in the fabrication of structural ceramics, ball-milling is a process of mixing or pulverizing powders. Despite its popular use, the effects of ball-milling on grain growth behavior are nevertheless still obscure. In this study, we investigated the effects of ball-milling on grain growth behavior in light of the crystal growth theory in a model NbC–Co system with partially faceted grains. Two kinds of 90NbC–10Co (wt %) samples, with and without ball-milling, were prepared. With ball-milling, the density of dislocations increased considerably. In samples without ball-milling, abnormal grain growth (AGG) occurred from the beginning of liquid phase sintering at 1450°C. In contrast, in samples with ball-milling, grain growth behavior was quite normal and large abnormal grains did not appear up to 96 h of sintering. These observations can be explained in terms of the change in the critical driving force for appreciable growth with dislocation density. The present results also demonstrate that proper mechanical treatment (ball-milling) can be useful for suppressing AGG in cemented carbide systems.
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Takeo SASAKI, Naoya SHIBATA, Katsuyuki MATSUNAGA, Takahisa YAMAMOTO, Y ...
2012 Volume 120 Issue 1407 Pages
473-477
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
JOURNAL
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TEM in-situ indentation experiments were applied to directly observe the atomic structures on the cleavage planes of sapphire, and the structures were determined by HRTEM image simulation. It was found that cracks mainly propagate along the low index planes of sapphire, forming the atomic scale steps on the cleavage planes, and the atomic structures are dependent on the crystal orientation. In addition, the surface structures of the cleavage planes were found to be reconstructed in the vicinity of the respective surfaces. For the (11
20) cleavage plane, the surface is composed of Al–O–Al cluster to form the complicated and metastable Al rich surface.
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Kenji SHIDA, Yusuke OHARA, Motohide MATSUDA, Yoko SUYAMA
2012 Volume 120 Issue 1407 Pages
478-482
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
JOURNAL
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Yttria-stabilized zirconia (YSZ) fibers various widths ranging from 36 to 66 µm of width were prepared by a drying process at 363 K from a zirconia sol containing 4 mol % yttria with 40 nm of primary particle size. The effects of preparation method on the crystal phase, microstructure and electrical properties of the obtained YSZ fibers were investigated. The obtained fibers were heat-treated at 1473 K for 1 h. The grain size and relative density of the fiber were 126 nm and 97%, respectively. The oxygen ion conductivity of the fiber showed heat-treated at 1473 K is 0.18 S/cm at 1273 K, which is the same as 8 YSZ bulk ceramics.
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Naoki YAMAMOTO, Toshihiro ISOBE, Sachiko MATSUSHITA, Akira NAKAJIMA
2012 Volume 120 Issue 1407 Pages
483-489
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
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The influences of drying temperature on the crystallinity and specific surface area of TiO
2 (rutile) powders prepared from acid treatments of BaTiO
3 were investigated. Then, Cu was grafted onto the obtained powders using two sources: CuCl
2 and (CH
3COO)
2Cu (CuAc
2). The resultant powders were bundle-like rutile nanorods. Although a freeze-dried sample showed lower crystallinity and specific surface area, they increased concomitantly with increasing drying temperature. Results suggest that a hydrothermal-like reaction occurs in the samples during drying. With grafting of Cu ions, photocatalytic performance for the decomposition of gaseous 2-propanol (IPA) under visible light was improved. The optimal Cu concentration of the solutions for grafting was around 0.1%. Samples treated using a CuAc
2 solution exhibited better photocatalytic activities than those treated using a CuCl
2 solution.
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Yasuhiko BENINO, Yuki OHTSUKI, Shinichi SAKIDA, Tokuro NANBA
2012 Volume 120 Issue 1407 Pages
490-493
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
JOURNAL
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Sodium borosilicate glasses containing phosphorus were prepared, and the effect of Al
2O
3 and TiO
2 addition on the distribution behavior of phosphorus atoms associated with the phase separation was investigated. After heat treatment, a phase separation by the spinodal decomposition was commonly confirmed by SEM observation. In the additive-free sample, phosphorus was preferentially distributed into B
2O
3-rich phase after the phase separation, and after adding Al
2O
3 or TiO
2, the amount of phosphorus distributed into SiO
2-rich phase increased. It was also suggested that TiO
2 had a stronger influence on the phosphorus distribution into SiO
2-rich phase than Al
2O
3.
31P MAS-NMR revealed that most of phosphorus atoms in the additive-free glass were present in PO
4 units consisting of two terminal oxide ions, and the terminal oxide ions decreased and increased after the additions of Al
2O
3 and TiO
2, respectively. It was suggested that this structural change brought about a change in the distribution of phosphorus.
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Makoto KOBAYASHI, Hideki KATO, Masato KAKIHANA
2012 Volume 120 Issue 1407 Pages
494-499
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
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Morphological control as well as formation of nanoparticles of anatase-type titanium dioxide has been achieved by a solvothermal treatment of a water-soluble citratoperoxotitanium (CPT) complex using ethylenediamine (EDA) as a key solvent in the presence of a given amount of water. When the EDA concentration in the whole solvent (EDA + H
2O) remained low less than 12 M, the powder obtained after the solvothermal treatment consisted of spindle-like anatase particles. With an increase of the EDA concentration in the solvent, the shape of the obtained particles changed from spindle to square bipyramid. When another water-soluble oxoglycolatoperoxotitanate complex or TiCl
4 was used as a starting source of Ti, similar shaped anatase particles could be obtained by a careful choice of synthetic conditions. Using a mixed solvent of EDA and water, sheet-like titanic acid was produced as an intermediate phase, regardless of the EDA concentration. Therefore, the formation of anatase in the current system may take place through dissolution-recrystallization of titanic acid. The formation of square bipyramidal anatase particle achieved in the present study is not agreement with a reported theoretical calculation of equilibrium phase, because the calculation reveals that truncated square bipyramid-like anatase is obtained under an acidic condition and spindle-like anatase was formed under a basic condition. An adsorption of EDA on particle surface and the pH of the solvent may contribute to the achievement of morphological control.
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Tomoaki WATANABE, Kazumichi NONAKA, JinWang LI, Kazuhisa KISHIDA, Masa ...
2012 Volume 120 Issue 1407 Pages
500-502
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
JOURNAL
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Because of its use as a mother crystal of red phosphor in white LEDs, SrAlSiN
3 is a very interesting complex nitride. Till date, the only examples of europium-doped SrAlSiN
3 synthesis have been in high-pressure nitrogen atmospheres at high temperatures above 2000 K at 190 MPa with typical solid-state reaction. In comparison, our research is the first to achieve such synthesis at an extremely low temperature of 773 K at 100 MPa. In addition, we document the first instance of synthesis using supercritical ammonia fluid with NaNH
2 as a reaction medium. Moreover, to our knowledge, this report details the first instance of synthesis of europium-doped SrAlSiN
3 by using dissolution and precipitation reaction. Reaction temperature and time dependencies of ammonothermal reactions for the product are investigated. The obtained product exhibits a red emission by irradiation of blue light of 460 nm.
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Yasushi SATO, Valery PETRYKIN, Hiroshi YASUOKA, Masato KAKIHANA
2012 Volume 120 Issue 1407 Pages
503-508
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
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Polycrystalline samples of YbBa
2Cu
3O
7−d and LuBa
2Cu
3O
7−d were prepared by polymerizable complex method. The combined results of both X-ray diffraction and Raman scattering analyses indicated that YbBa
2Cu
3O
7−d sample was of single phase when the samples were sintered in a low oxygen partial pressure (1%) at relatively low temperature (845°C). On the other hand, LuBa
2Cu
3O
7−d sample was only slightly contaminated with a very small amount of Lu
2BaCuO
5 and BaCuO
2 impurities when the sample was prepared under the same condition as YbBa
2Cu
3O
7−d. Ac complex magnetic susceptibility measurements exhibited that a transition into the superconducting state for YbBa
2Cu
3O
7−d and LuBa
2Cu
3O
7−d samples was sharp and smooth, implying that both of the samples were of “superconducting” single phase. The
Tc onset values of the YbBa
2Cu
3O
7−d and LuBa
2Cu
3O
7−d, were 93.4 and 92.3 K, respectively.
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Keita KANENISHI, Shinichi SAKIDA, Yasuhiko BENINO, Tokuro NANBA
2012 Volume 120 Issue 1407 Pages
509-512
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
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Surface crystallized glass-ceramics with nonlinear optical Bi
2ZnB
2O
7 (BZB) crystals were prepared by ultrasonic surface treatment (UST) followed by crystallization heat treatment for stoichiometric glass with a composition of 33.3Bi
2O
3–33.3ZnO–33.3B
2O
3. According to the surface XRD measurements and microscopic observations, UST technique was found to be quite effective for lower temperature precipitation of BZB, indicating the ability of crystallization control of the target phase, such as phase selectivity, small size of precipitates, high orientation and their morphology. After the optimization of the process condition parameters for improving transparency and suppressing deformation of the sample, the effective optical nonlinearity of the transparent surface crystallized glass-ceramics was estimated as 0.7 pm/V.
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Yongzhao YAO, Takashi SEKIGUCHI, Takeshi OHGAKI, Yutaka ADACHI, Naoki ...
2012 Volume 120 Issue 1407 Pages
513-519
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
JOURNAL
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The influences of sapphire (Al
2O
3) substrate nitridation on the growth of GaN and InN by plasma-assisted molecular-beam epitaxy (PAMBE) were studied by using reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), and X-ray diffraction (XRD). Three factors have been investigated, including (1) the effect of ionic nitrogen species; (2) nitridation time; and (3) substrate temperature (T
s). RHEED and AFM results have suggested that although AlN formation on sapphire during nitridation is faster when ionic nitrogen species are present or when T
s is higher, the resultant AlN layer is not as homogeneous as that formed without ionic nitrogen species and/or at lower T
s. An inhomogeneous AlN coverage on sapphire leads to GaN and InN growth with more defects, especially to a serious twist misorientation in the case of InN. Optimal nitridation conditions in this experiment have been found to be applying ion-free nitrogen species at T
s = 300°C for a duration about 300 min.
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Yuki SHIROSAKI, Hiroki YOSHIHARA, Song CHEN, Mark BLEVINS, Yuri NAKAMU ...
2012 Volume 120 Issue 1407 Pages
520-524
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
JOURNAL
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Silica fiber mats were fabricated by soaking electro-spun poly(vinyl alcohol) fibril mat in NH
4OH-catalyzed (Stöber type) colloidal silica sol and silica oligomer solution from HCl-catalysis of the system tetraethoxysilane, ethanol, and water, followed by appropriate heat treatments. The silica fibrils from the Stöber silica sol were hollow nano-tubes (NT) consisting of nano-sized silica particles, while the silica nanofibers (NF) from the acid-catalyzed sol were solid with minimal porosity. A model was proposed for the NF and NT formation processes.
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Hye Young JUNG, Yoo Youl CHOI, Hyung Keun KIM, Doo Jin CHOI
2012 Volume 120 Issue 1407 Pages
525-529
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
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An investigation was conducted involving the memory characteristics of the Pt/Al
2O
3/Y
2O
3/SiO
2/Si structure using a high-k Y
2O
3 charge trapping layer for SONOS (poly-silicon/oxide/nitride/oxide/silicon)-type nonvolatile memory applications. This work focused on Y
2O
3 layer deposition at different substrate temperatures, which ranged from 450–550°C by metal organic chemical vapor deposition (MOCVD) and examined the electrical properties and structural differences of each specimen. Results showed that the Y
2O
3 deposited at 500°C had the highest memory characteristics and reliability than the other deposition condition. The maximum memory window of capacitor with an Y
2O
3 trapping layer deposited at 500°C was 3.11 V which well endured up to 10
4 program/erase (P/E) cycles. The results indicated that deposition temperature is one of the most critical factors influencing the charge trapping properties.
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Satoshi FUKUI, Shinichi SAKIDA, Yasuhiko BENINO, Tokuro NANBA
2012 Volume 120 Issue 1407 Pages
530-533
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
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SnO–P
2O
5 glasses have high refractive index and low glass transition temperature but have poor water durability. To improve water durability, NbO
2.5 was added to SnO–P
2O
5 glasses, preparing SnO–NbO
2.5–P
2O
5 glass. It was found that addition of only 4 mol % NbO
2.5 was enough to achieve significant improvement of water durability, and at the same time, no degradation in thermal and optical properties was observed.
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Takeshi NOMURA, Shunsuke NISHIMOTO, Yoshikazu KAMESHIMA, Michihiro MIY ...
2012 Volume 120 Issue 1407 Pages
534-538
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
JOURNAL
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K
2NiF
4-type Pr
2NiO
4 doped with Cu, Cu–Ga, or Co (Pr
2Ni
0.9Cu
0.1O
4, Pr
2Ni
0.75Cu
0.25O
4, Pr
1.91Ni
0.71Cu
0.24Ga
0.05O
4, or Pr
2Ni
0.9Co
0.1O
4) were synthesized by a solid-state reaction for use as cathodes in an intermediate-temperature (500–700°C) solid oxide fuel cell (IT-SOFC). Pr
2NiO
4, Pr
2Ni
0.9Cu
0.1O
4, Pr
2Ni
0.75Cu
0.25O
4, Pr
1.91Ni
0.71Cu
0.24Ga
0.05O
4, and Pr
2Ni
0.9Co
0.1O
4 crystallize in the space group
Bmab. Single test cells with samarium oxide doped ceria (SDC) as the electrolyte, Ni-SDC cermet as the anode, and the above-mentioned cathode material were fabricated for cell performance measurements at 700°C. Current interruption measurements and electrochemical impedance spectroscopic analysis revealed that the cathode properties of Pr
2NiO
4, Pr
2Ni
0.9Cu
0.1O
4, Pr
2Ni
0.75Cu
0.25O
4, and Pr
1.91Ni
0.71Cu
0.24Ga
0.05O
4 were comparable to that of La
0.6Sr
0.4Co
0.2Fe
0.8O
3 (LSCF) and the cathode properties of Pr
2NiO
4 were improved by doping with Cu or Cu–Ga at the Ni site of Pr
2NiO
4.
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Dae-Min KIM, Sung-Min LEE, In-Ki KIM, Byung Koog JANG, Dae-Soon LIM, Y ...
2012 Volume 120 Issue 1407 Pages
539-543
Published: November 01, 2012
Released on J-STAGE: November 01, 2012
JOURNAL
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The Y
2O
3 films were deposited on quartz plates using an electron beam (EB) evaporation method with different interlayer. The two types of interlayer, which were compositionally graded and alternated stacks of Y
2O
3 and SiO
2 layer, were applied with the intent to prevent flaking of the coating due to a thermal mismatch between the Y
2O
3 film and quartz substrate. The field emission scanning electron microscopy (FESEM) analysis indicated that the Y
2O
3 film with interlayer which consisting of alternated stacks of Y
2O
3 and SiO
2 layer, shows more structural stability, no crack propagation or flaking of the top layer, than other film samples. The plasma resistance of the Y
2O
3 films was analyzed by a plasma etching test using inductively coupled plasma (ICP) conditions with a gas mixture of CF
4/O
2. The etching resistance of the Y
2O
3 films was evaluated by measurement of etching depth. The etching depths of Y
2O
3 films with interlayer were shown as 20 times lower than quartz plate.
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Feature: Advanced Ceramic Science and Technology in the Western Pacific Rim Area: Technical report
Feature: Advanced Ceramic Science and Technology in the Western Pacific Rim Area: Notes