Journal of the Ceramic Society of Japan
Online ISSN : 1348-6535
Print ISSN : 1882-0743
ISSN-L : 1348-6535
119 巻, 1392 号
(August)
選択された号の論文の11件中1~11を表示しています
Review
  • Hidero UNUMA, Yuta MATSUSHIMA, Takahiro KAWAI
    2011 年 119 巻 1392 号 p. 623-630
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    Some enzymes catalyze the formation of precipitants of metal ions, and some others directly interact with metal-containing precursors. Such enzymes allow the synthesis of inorganic solids under mild conditions. Due to the nature of enzymatic reactions, enzyme-mediated ceramic synthesis techniques can facilitate (1) site-selective ceramic deposition, (2) low temperature ceramic synthesis, (3) intact combination of ceramics with heat-sensitive materials, and sometimes (4) synthesis of metastable phases. The morphology of the resultant ceramics can be tailored in many ways by immobilizing enzymes onto various templates. So far, successful cases have been reported in preparing thin film coatings, hollow micro- or nanospheres, multi-layer stacking, nanotubes, 2D patterns, honeycombs, 3D replicas of biominerals, and so on. Enzyme-mediated ceramic synthesis provoked the emergence of a new type of processing technique which employs proteins or peptides as the mediators. Practical applications of enzyme- or peptide-mediated ceramics are on the horizon in many fields, such as biomaterials, enzyme immobilization supports, and enzyme sensors. This article presents a comprehensive survey of the recent advances of enzyme-mediated ceramic synthesis and related techniques as well as future outlook.
Papers
  • Laiping ZHANG, Yunle GU, Weiming WANG, Jilin WANG, Guowei ZHAO, Qiongl ...
    2011 年 119 巻 1392 号 p. 631-634
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    Single phase of boron carbide B13C2 ultrafine powders was synthesized by a fast-pyrolysis-self-propagating high temperature synthesis method. The X-ray diffractometry is demonstrated a pure phase of rhombohedral structure. The field-emission scanning electron microscopy and transmission electron microscopy show that the size of particles ranged from 50 to 200 nm, with approximately 90 nm in average. The energy dispersive X-ray spectroscopy reveals that the sample has a uniform composition with the B/C atomic ratios ranging from 6.38 to 6.49. The Raman spectrum indicates the characteristic vibrations of C–B–C chain and B12 icosahedron. Fast-pyrolysis-self-propagating high temperature synthesis and vapor–solid growth mechanism ware proposed.
  • Shinnosuke OKADA, Yuya OAKI, Jun KOMOTORI, Hiroaki IMAI
    2011 年 119 巻 1392 号 p. 635-639
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    電子付録
    We studied the activity of osteoblastic cells on biphasic calcium phosphate (BCP) containing ca. 50 wt % hydroxyapatite and ca. 50 wt % β-tricalcium phosphate. The influence of the microtopography on the cellular activity was investigated by using three kinds of BCP scaffolds, which were composed of densely packed domains of 3–5 µm in size (dense-BCP), a porous framework of ∼1 µm in width (micro-BCP), and aggregated particles of ∼100 nm in diameter (nano-BCP). Basically, stable adhesion of the cells was achieved with defined focal adhesions on the BCP scaffolds regardless of their topography. The alkaline phosphatase (ALP) activity in the initial stage of the adhesion was more enhanced on micro- and nano-BCPs than it was on dense-BCPs due to the presence of a large number of calcium ions eluted from small grains in the micro- and nano-BCPs. However, the proliferation and the ALP activity were suppressed in the long-term culture on nano-BCP because of the limitation of the domain area for the formation of focal adhesions. Therefore, the cellular activity was successfully controlled with the surface microtopography of the scaffolds. The microstructured surface providing a sufficient domain area and essential ions would be suitable as a scaffold for osteoblastic cells.
  • Sea-Hoon LEE
    2011 年 119 巻 1392 号 p. 640-644
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    Dense SiC was obtained at 1525°C under 40 MPa pressure after sintering a sub-micrometer scale SiC powder for 3 h using Al8B4C7 and carbon additive. Densification was also accomplished within 1 min by increasing sintering temperature and pressure to 1575°C and 120 MPa. The average grain size could be maintained to 0.71 µm when using SiC powder having 0.55 µm in size by decreasing sintering temperature and time. Viscous flow and grain boundary sliding initiated sintering and liquid phase sintering occurred at the final stage. The formation of a core–rim structure within SiC grains indicated that liquid phase sintering occurred during densification. The sintering behavior of sub-micrometer scale SiC powder is similar with that of nano-SiC powder when using Al8B4C7 additive. The sintered SiC had high Young’s modulus (368 GPa) and fracture toughness (4.7 MPa·m1/2) after sintering at 1575°C for 1 min.
  • Anton TRNÍK, Igor ŠTUBŇA, Gabriel VARGA, Peter BA ...
    2011 年 119 巻 1392 号 p. 645-649
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    Mechanical behavior of the heatproof stove tile ceramic material Letovice, which consists of kaolinitic clays and quartz, and small amount of mica, calcite and feldspar, was studied using the non-destructive sonic resonant method mf-TMA. To find actual dimensions and the volume mass of the sample, thermodilatometry and thermogravimetry were carried out in the same temperature regime (20–1100°C, 5°C/min) as mf-TMA. It was found that liberation of the physically bounded water from the green mass makes Young’s modulus higher. Dehydroxylation of phyllosilicates and the α → β transformation of quartz affect Young’s modulus to a lesser degree. The collapse of phyllosilicates structure above 900°C and the creation of mullite cause an increase in Young’s modulus.
  • Hidetoshi MIYAZAKI, Atsushi NOSE, Hisao SUZUKI, Toshitaka OTA
    2011 年 119 巻 1392 号 p. 650-653
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    Phosphorus solid-soluted WO3 ceramics (PxW1−xO3) were fabricated by a solid state reaction at 1000°C for 100 h with the phosphorus concentration x of 0 to 0.3. Phosphorus-doped single-phase monoclinic WO3 ceramics were fabricated with phosphorus concentration between 0 and 0.3. Sintered WO3 pellets that were P-doped with phosphorus concentrations of 0–0.3 were synthesized at 1000°C in 24 h in order to evaluate electric and dielectric properties. The resistivity of specimens decreased concomitantly with increasing the stoichiometry x in PxW1−xO3 from 0 to 0.15, and that increased with increasing phosphorus concentration larger than 0.15. The dielectric constants of the specimens decreased with increase of phosphorus concentration, and the dielectric constant of the P0.05W0.95O3 and P0.10W0.90O3 were 2100 and 1400 at 100 kHz at room temperature, respectively.
  • Wenjuan WU, Dingquan XIAO, Jiagang WU, Jing LI, Jianguo ZHU
    2011 年 119 巻 1392 号 p. 654-657
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    Lead-free piezoelectric ceramics (K0.474Na0.474Li0.052)(Nb0.948Sb0.052)O3x%Co2O3 [KNLNS–x%Co2O3] were prepared by the conventional solid-state sintering method. The effects of the Co2O3 addition (0.03–0.40 mol %) on the phase structure and piezoelectric properties of KNLNS ceramics were systematically studied. The phase structure of KNLNS–x%Co2O3 ceramics at room temperature is the coexistence of orthorhombic–tetragonal phases, and only a small amount of Co2O3 additives can diffuse into KNLNS lattices to form a stable solid solution. The density of ceramics increases gradually with the introduction of Co2O3. KNLNS–0.1 mol %Co2O3 lead-free ceramics exhibit optimum properties (d33 = 262 pC/N, kp = 0.40, εr = 1025, tan δ = 0.03 and Tc = 352°C), owing to the TO–T near room temperature and the dense microstructure. The underlying physical mechanisms were clearly addressed. These results indicate that the KNLNS–x%Co2O3 ceramics are a promising candidate material for lead-free piezoelectric ceramics.
  • Ken’ichiro KITA, Naoki KONDO, Yasuhisa IZUTSU, Hideki KITA
    2011 年 119 巻 1392 号 p. 658-662
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    This paper describes a novel experiment involving the joining of alumina using polycarbosilane (PCS). PCS filled in the cracks on the surface of alumina, the silicon in PCS oxidized to silicon dioxide (SiO2), and part of SiO2 reacted with alumina to form mullite during pyrolysis of PCS at 1673 and 1873 K. The SiO2 and mullite acted as a binder between the alumina boards. 4-point bending tests showed the average flexural strength of the samples pyrolyzed at 1673 K was 81.8 MPa, whereas that of the samples that pyrolyzed at 1873 K was 109 MPa. The difference in flexural strength was caused by the difference in the thickness and the compounds of the joining area, which was brought by the diffusion of the decomposition products derived from PCS and alumina during pyrolysis.
  • Akira MIURA, Michael WESSEL, Richard DRONSKOWSKI
    2011 年 119 巻 1392 号 p. 663-666
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    The electronic structure (band structure, DOS and COHP) of the delafossite nitride AgTaN2 was investigated on the basis of density-functional theory using the generalized-gradient approximation (GGA). AgTaN2 is predicted to be a semiconductor with an indirect band gap. The characters of the top of the valence band and the bottom of the conduction band are attributed to Ag–N antibonding and Ta–N antibonding interactions, respectively. These results were compared to the bonding situation in isostructural AgGaO2. With increasing pressure, the electronic structure of AgTaN2 changes. At a pressure of ca. 42 GPa, the indirect band gap should transform into a direct one, and at even higher pressures (above 65 GPa) AgTaN2 should become metallic.
  • Tohru S. SUZUKI, Tetsuo UCHIKOSHI, Saki SAKAKIBARA, Hiroyuki MUTO, Ats ...
    2011 年 119 巻 1392 号 p. 667-671
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    Silicon carbide is a very important material for various applications and its properties are expected to be improved by controlling the crystallographic orientation. It was difficult to simultaneously consolidate SiC powder and sintering additives by electrophoretic deposition (EPD) because of the different electrophoretic mobility. When using the alumina-coated SiC by the sol–gel method, it is possible to deposit SiC and sintering additives by EPD at the same time.
    In this study, we demonstrated that the c-axis alignment of SiC was controlled by EPD and a strong magnetic field, and we investigated the effect of the surface-modification on the microstructure and the degree of orientation. The dilute solution and the large number of repeated coating times prevent the oxide phase from precipitating at the multiple grain junctions and enhance grain growth. The grain growth promoted the degree of orientation in the textured SiC prepared by EPD in a strong magnetic field.
  • Hiroaki KATSUKI, Nobuaki KAMOCHI, Atsunori SHIRAISHI, Woo-Seok CHO, Ja ...
    2011 年 119 巻 1392 号 p. 672-676
    発行日: 2011/08/01
    公開日: 2011/08/01
    ジャーナル フリー
    Old celadon samples produced at four early Arita kiln sites in the 1640–1650’s were used for the macroscopic, microscopic, compositional, and color studies of glaze and body using XRD, SEM, XRF and colorimeter. Molar ratio of SiO2/Al2O3 of the early Arita celadon glaze was 8.4–9.3, and the glaze and body had 1.68–3.95 and 1.07–2.21 wt % Fe2O3, respectively. The total amount of MgO and CaO in the glaze was 12.2–14.9 wt %. The celadon color of the early Arita celadon was influenced by a small amount of Fe2O3 in the glaze and body. The body was mainly composed of α-quartz, mullite, and glass, and the average particle size of α-quartz was 17–30 µm and 2–3 times larger than that of the modern celadon. Some characteristics were compared with those of the early Korean Koryõ celadon reported in some literatures.
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