Journal of the Ceramic Society of Japan
Online ISSN : 1348-6535
Print ISSN : 1882-0743
ISSN-L : 1348-6535
Volume 127 , Issue 7
(July)
Showing 1-12 articles out of 12 articles from the selected issue
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  • Daiki SHIRATORI, Yuya ISOKAWA, Hayata SAMIZO, Noriaki KAWAGUCHI, Takay ...
    2019 Volume 127 Issue 7 Pages 455-461
    Published: July 01, 2019
    Released: July 01, 2019
    JOURNALS FREE ACCESS

    We prepared glass samples with a chemical composition of 30KPO3–70Al(PO3)3 by the melt quenching method. As a radio-photoluminescence (RPL) emission center, Ag2O (0, 0.1, 0.3, 1.0 and 3.0%) was doped in these glasses. Before X-ray irradiation, Ag-doped samples showed a blue luminescence upon 254 nm excitation while they exhibited an orangish luminescence upon 304 nm excitation after X-ray irradiation. We evaluated dosimeter properties such as dose response properties of RPL, fading and thermally stimulated luminescence (TSL) glow curves. Dose response function in RPL emission indicated the lower detection limit of 100 mGy. In addition, TSL glow curve of Ag-doped 30KPO3–70Al(PO3)3 showed that accumulated carriers in the samples were released at around 85°C and easily re-excited at room temperature.

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  • Fumika SAKAMOTO, Takuma TAKAHASHI, Junichi TATAMI, Motoyuki IIJIMA
    2019 Volume 127 Issue 7 Pages 462-468
    Published: July 01, 2019
    Released: July 01, 2019
    JOURNALS FREE ACCESS

    Non-destructive analysis is important in terms of improving the reliability of ceramics. In the study, the internal structure of Al2O3 ceramics with artificial pores was observed via optical coherence tomography (OCT). The OCT observation was performed on a surface perpendicular to the tensile surface of the specimen. The spherical pores were successfully observed via OCT. The strength and fracture origin were predicted from the size and position of the observed pores. The lowest predicted strength (which is realized as the strength of the specimen) was in agreement with the bending strength obtained via three-point bending tests. The actual fracture origin observed by scanning electron microscope was also the same as that predicted via the OCT observation. Thus, the results indicated that the nondestructive testing via OCT was useful in terms of predicting the strength and fracture origin of ceramics.

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  • Yushi QI, Gang CHEN, Yehong CHENG, Wenbo HAN, Zhiming DU
    2019 Volume 127 Issue 7 Pages 469-473
    Published: July 01, 2019
    Released: July 01, 2019
    JOURNALS FREE ACCESS

    ZrB2–SiC porous ceramics with different porosities were prepared by spark plasma sintering. The effects of temperature and pressure on the porosity and mechanical properties were studied. The properties of samples after oxidation at 1773 K were also investigated. The sample sintered at 2073 K for 5 min without pressure showed better comprehensive performance. The porosity, flexural strength and fracture toughness were 38.6%, 108.6 MPa and 1.7 MPa·m1/2, respectively. In contrast, the flexural strength of ZS1 (1973 K, 0 MPa, 5 min), ZS2 (2073 K, 0 MPa, 5 min) and ZS3 (1973 K, 10 MPa, 5 min) were remarkably improved after oxidation, reached 97.2, 166.4, 200.9 MPa, respectively. After oxidation, the fracture toughness of ZS1, ZS2 and ZS3 were 2.57, 2.34 and 2.63 MPa·m1/2, respectively. The ZrB2–SiC porous ceramics fabricated in this paper will have considerable application in the composite material field.

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  • Shintaro YASUI, Tsukasa KATAYAMA, Takuya OSAKABE, Yosuke HAMASAKI, Tom ...
    2019 Volume 127 Issue 7 Pages 474-477
    Published: July 01, 2019
    Released: July 01, 2019
    JOURNALS FREE ACCESS

    RhxFe2−xO3 solid-solution epitaxial thin films were prepared by pulsed laser deposition. The ferroelectricity of Rh0.15Fe1.85O3 thin film was presented by the result of piezoelectric force microscopy phase and amplitude loops measured at room temperature. Ferrimagnetism at room temperature is confirmed by the magnetic hysteresis loop. The coercive field of Rh0.15Fe1.85O3 thin film at 5 K is 12 kOe, which is larger than that of ε-Fe2O3. Rh0.15Fe1.85O3 is confirmed to be a room temperature multiferroic material.

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  • Yoshiharu ITO, Akinori TATEYAMA, Yoshiko NAKAMURA, Takao SHIMIZU, Mino ...
    2019 Volume 127 Issue 7 Pages 478-484
    Published: July 01, 2019
    Released: July 01, 2019
    JOURNALS FREE ACCESS

    (K,Na)NbO3 thick films were grown at 240°C on Ni-based metal substrates by repeated hydrothermal method. The metal substrates were covered with two types of buffer layers; SrRuO3/LaNiO3 and SrRuO3. Film thickness monotonically increased with increasing number of deposition cycles. The 27 µm-thick film was obtained on the metal substrate with SrRuO3/LaNiO3 by four cycles. The obtained films tended to show {100}c orientation and their degree of orientation increased with increasing number of deposition cycles. Films deposited on SrRuO3/LaNiO3-covered metal substrates showed more highly {100}c orientation compared with those on SrRuO3-covered metal substrates. Remnant polarization and coercive field measured at 5 kHz were 12 µC/cm2 and 70 kV/cm, while their effective values of piezoelectric coefficient (d33) was 35–40 pm/V for both films. These properties remained unchanged irrespective of a number of deposition cycles despite the orientation change of films. These results show that repeated hydrothermal deposition technique is one of the effective ways to prepare thick (K,Na)NbO3 films on metal substrates.

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  • Yuki YAMAGUCHI, Hirofumi SUMI, Hiroyuki SHIMADA, Yoshinobu FUJISHIRO
    2019 Volume 127 Issue 7 Pages 485-490
    Published: July 01, 2019
    Released: July 01, 2019
    JOURNALS FREE ACCESS

    In this study, we prepare Ba0.5Sr0.5Co0.8Fe0.2O3–δ (BSCF) cathodes using the reactive sintering method. BSCF is known as a candidate for cathode material of intermediate temperature solid oxide fuel cell. This BSCF cathode is fabricated on the anode supported cells at a low-temperature of 700°C in order to overcome a crystal phase transition from cubic to hexagonal. Utilizing the reactive sintering, hexagonal BSCF cathode can be synthesized and sintered at 700°C by using the intermediate compound of BSCF. In addition, the reactive sintering can improve the sinterability of BSCF and decrease the ohmic and polarization resistances of the cells. The anode supported cell having hexagonal BSCF cathode shows a good power output, compared with the sample made from a commercial cubic BSCF powder. Its maximum power output reaches to ca. 1 W cm−2 at 700°C. It is considered that the reactive sintered BSCF cathode layer has a good interface with gadolinium doped ceria interlayer. It is found the hexagonal BSCF has good cathode properties if the cathode sintered well at low-temperature.

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  • Taku KISHIMOTO, Atsushi SUZUKI, Naoki UEOKA, Takeo OKU
    2019 Volume 127 Issue 7 Pages 491-497
    Published: July 01, 2019
    Released: July 01, 2019
    JOURNALS FREE ACCESS

    CH3NH3PbI3−xClx-based photovoltaic devices with guanidinium [C(NH2)3, GA] were fabricated and characterized. The additive effects of guanidinium iodide, formamidinium [CH(NH2)2, FA] iodide, and guanidinium chloride were compared. Short-circuit current densities, open-circuit voltages, series resistances and shunt resistances were improved by the GA addition. The short-circuit current densities were increased by FA addition with GA. The incident photon-to-current conversion efficiency increased, which results from the suppression of pin-holes in perovskite layers by GA addition. The conversion efficiencies were improved by GA addition. X-ray diffraction showed that the lattice constants of the perovskite crystals increased by GA and FA addition, and that the GA substituted partially at the CH3NH3-site.

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  • Tsu-Chia CHAO, Subramanian SAKTHINATHAN, Te-Wei CHIU, Yongsheng FU
    2019 Volume 127 Issue 7 Pages 498-503
    Published: July 01, 2019
    Released: July 01, 2019
    JOURNALS FREE ACCESS

    Delafossite CuFeO2 anisotropic thin films were prepared by electrospinning method with rotating collector. The pure phase CuFeO2 anisotropic thin films were prepared by heat treatment at 773 K in the air for 600 s and 1023 K under nitrogen for 600 s. Besides, an electrospinning process rotation speed influence on the CuFeO2 film formation. The delafossite-type CuFeO2 films were identified by X-ray diffraction and field emission scanning electronic microscopy. High-speed rotating collector were used to prepare the anisotropic thin film. Glass substrates were fixed on a rotating collector and rotated at speeds of 100–3000 rpm. The optical and electrical properties of the prepared CuFeO2 thin film were measured by ultraviolet–visible spectrometry and two-point probe method, respectively. The electrical resistance of the macroscopically anisotropic CuFeO2 thin films in the parallel and vertical directions showed a difference of 2–3 orders.

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  • Satoshi SUEHIRO, Teiichi KIMURA
    2019 Volume 127 Issue 7 Pages 504-506
    Published: July 01, 2019
    Released: July 01, 2019
    JOURNALS FREE ACCESS

    Reaction sintering of silicon carbide (SiC) using a continuous-wave Nd:YAG laser as a heating source was investigated. The laser was used to irradiate pellets of a stoichiometric powder mixture of Si and C under Ar gas flow. At an appropriate laser power, a dense SiC layer was formed consisting of grains with a size of 100–500 nm; this layer was several micrometers thick. At lower laser power, fine grains of SiC were formed and dispersed in the unreacted Si–C matrix. On the other hand, at higher power, larger faceted SiC grains (1–3 µm) were formed.

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