Transactions of the Materials Research Society of Japan
Online ISSN : 2188-1650
Print ISSN : 1382-3469
ISSN-L : 1382-3469
43 巻 , 2 号
選択された号の論文の17件中1~17を表示しています
Review Paper
Regular Papers
  • Te-Wei Chiu, Chien-Hung Chen, Heng-Yi Shih, Horng-Yi Chang, Yao-Ming W ...
    2018 年 43 巻 2 号 p. 43-47
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    In this study, Pr2CuO4 was fabricated as a cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs) application. The Pr2CuO4 cathode was prepared using a solid-state reaction and an electrospinning technique. The prepared cathode material was characterized by the suitable characterization technique. The Pr2CuO4 was coated on a Sm0.2Ce0.8O1.9 (SDC20) pellet with a doctor blades to form a half-cell (Ag/Pr2CuO4/SDC20/Ag). The Pr2CuO4 cathode prepared using electrospinning method demonstrated an excellent cathode performance in electrochemical measurements. The fiber morphologies of the cathode induced large amounts of triple phase boundaries, which promoted oxygen diffusion on the surface. The lowest area-specific resistance obtained with the Pr2CuO4 fiber was determined to be 0.35 Ω cm2 at 800°C in air. The electrospinning prepared Pr2CuO4 fiber is a potential cathode material for IT-SOFCs.

  • Naofumi Nishikawa, Satoshi Takeichi, Takanori Hanada, Shuya Tategami, ...
    2018 年 43 巻 2 号 p. 49-52
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite (UNCD/a-C:H) films possess the following specific characteristics: (a) the appearance of additional energy levels in diamond bandgap and (b) large absorption coefficients ranging from visible to ultraviolet, both of which might be due to large number of grain boundaries between UNCD grains and those between UNCD grains and a-C:H. Owing to them, UNCD/a-C:H films are expected to be applied to photovoltaics such as UV sensors. Actually thus far, we have fabricated pn heterojunction diodes comprising p-type UNCD/a-C:H films and n-type Si substrates, and confirmed their photovoltaic action. In this study, the minority carrier lifetime, which is an important factor for photovoltaics, was experimentally measured by microwave reflected photoconductivity decay, and it was estimated to be 0.21 and 0.43 μs for UNCD/a-C and UNCD/ a-C:H, respectively. In addition, on the basis of the previous work on the heterojunctions, the effects of hydrogenation on the photovoltaic action of the heterojunctions were studied. The photocurrent apparently increases with an enhancement in the hydrogenation of UNCD/a-C:H films, which might be because dangling bonds in the UNCD/a-C:H films, which act as photogenerated-carrier trap centers, are terminated by hydrogen atoms.

  • M. Ochi, H. Kojima, K. Fukuda, Y. Kaneno, S. Semboshi, F. Hori, Y. Sai ...
    2018 年 43 巻 2 号 p. 53-56
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    To investigate the thermal stability of the ion-irradiation induced metastable lattice structures in bulk samples of NiTi intermetallic compound, they were irradiated with 16MeV Au ions at room temperature, and were subsequently annealed up to 823K. The lattice structures of the irradiated samples and the annealed samples were examined by using the x-ray diffraction. The measurements have also been performed for NiTi irradiated at 523K. The amorphous state induced by 16MeV Au ion irradiation at room temperature recovers to the intrinsic B19' structure by the thermal annealing above 673K. The lattice structure, however, hardly changed even after the irradiation at 523K. The experimental result implies that the thermal motion of atoms in NiTi during the irradiation is much more effective for the recovery of the irradiation effect. The effect of thermal annealing on the surface hardness is also discussed.

  • Md. Nazmul Kayes, Md Jalil Miah, Mohammad Shahabuddin, Michinori Karik ...
    2018 年 43 巻 2 号 p. 57-60
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    A polycondensed 2,15-dihydroxy-hexahelicene (HELIXOL) was used to prepare thin films by Langmuir-Blodgett (LB) and spin-coating (SP) techniques, and their structural and photoelectrochemical characteristics were investigated. Atomic force microscopic (AFM) observation indicated that, though the molecule possesses both the hydrophilic –OH groups and hydrophobic aromatic rings, a homogeneous monolayer was not formed by the LB technique, which may be due to lack of sufficient hydrophilicity of the molecule. On the other hand, films with uniform thickness were formed by the SP technique although many holes were generated most likely due to aggregation of the HELIXOL molecules in solvent evaporation process. The energy difference between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) was estimated by cyclic voltammetry (CV), and the optical band gap energy was determined from the UV-visible spectra. The photocurrent generation was also confirmed through a cyclic light-irradiation experiments with a conventional three-electrode system.

  • Keiichi Kaneto, Hiroki Takahashi, Fumito Hata, Sadahito Uto
    2018 年 43 巻 2 号 p. 61-64
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    Conducting polymers expand and contract by electrochemical oxidation and reduction, respectively. The electrochemical deformation (strain), which is caused by insertion and exclusion of anion, demonstrates artificial muscles (softactuator). The magnitude of strain depends on bulkiness (size) and number of inserted anions. The contraction force (stress) is associated with the elasticity of polymers. In this study the electrochemical strain has been measured as a function of tensile loads to elucidate the mechanism of electrochemical stress in conducting polymer, polyaniline films in various acid electrolytes. The results of electrochemical stress are compared with the elasticities of the films obtained by static stress-strain curves. The electrochemical stress is qualitatively discussed based on the elasticity of the films and anion size of various acid electrolytes.

  • Hirofumi Shibata, Yusuke Kanie, Yuya Kato, Toru Nonami
    2018 年 43 巻 2 号 p. 65-70
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    Anodized titanium plates were produced as implant material, using powdered titanium oxide suspended in sulfuric acid aqueous solution electrolyte. Based on X-ray diffraction (XRD) and Auger electron spectrometry analyses, the formation of approximately 2800-nm-thick surface oxide film on titanium consisting of rutile and anatase phases was confirmed. This oxide film on titanium contained many submicron-size pores. The anodized titanium plate was immersed in simulated body fluid, and evaluated using scanning electron microscopy and XRD. Low-crystalline hydroxyapatite formed on the surface after seven days of immersion. In contrast, a 270-nm-thick oxide film was produced on titanium plate anodized in phosphoric acid aqueous solution. In this instance, no additional layer was observed on the surface even after seven days of immersion in simulated body fluid. The biocompatibility was presumed to have improved in the titanium plate anodized using titanium oxide suspended in sulfuric acid aqueous solution electrolyte, because of the formation of a thick oxide film that contained a large number of pores. This material was thus found to be promising for use in implants.

  • Shohei Ida, Masamitsu Yamawaki, Tatsuya Maruta, Yoshitsugu Hirokawa
    2018 年 43 巻 2 号 p. 71-74
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    End-crosslinking of telechelic prepolymers is attractive for the construction of homogeneous network structure toward the development of functional gel materials. In this paper, we demonstrated the usefulness of thiol-ene reaction as crosslinking reaction in combination with prepolymer synthesis by reversible addition-fragmentation chain transfer (RAFT) polymerization. Telechelic poly(N-isopropylacrylamide) (PNIPAAm) with thiol-termini was successfully prepared by RAFT polymerization followed by aminolysis reaction. The obtained prepolymers were employed for the reaction with four-armed vinyl compounds as a crosslinker in various solvent. It demonstrated that the polarity of the solvent strongly affected the molecular weight of the product and, in particular, a stable gel was obtained in methanol. The effect of the molecular weight and the feed concentration was also examined and it clarified that thiol-ene reaction gave an efficient crosslinking reaction. These results indicated that the combination of RAFT polymerization and thiol-ene reaction is suitable for end-crosslinking system.

  • Yoshitaka Suzuki, Tomoya Kitagawa, Yoji Namekawa, Minoru Matsukura, Ka ...
    2018 年 43 巻 2 号 p. 75-80
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    The production of 99Mo via a (n, γ) reaction is a simple and easy method and is advantageous from the viewpoints of nuclear proliferation resistance and waste management. However, the production of 99 mTc solutions with heavy levels of radioactivity is difficult because the specific radioactivity of 99Mo produced via this method is extremely low. Thus, it is necessary to develop a novel adsorbent with high Mo-adsorption efficiency. In this study, alumina (Al2O3), which is often used in medical 99Mo/99 mTc generators, was used as the Mo adsorbent. Al2O3 specimens were prepared with three types of starting powders and sintered at different temperatures; in addition, their Mo adsorption and desorption properties were evaluated. The results indicated that the Mo-adsorption properties are influenced by the crystal structure and the specific surface of the Al2O3. In addition, the basic chemical properties of the solution eluted from each developed Al2O3 specimen were within the limits given by the guidelines.

  • T. Tsuda, C. Nakagawa, Y. Takeda, H. Cho
    2018 年 43 巻 2 号 p. 81-84
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    In this research, the effects of heating/cooling water temperatures of a heat engine on the output characteristics of the forced cooling pulley-type SMA heat-engine is investigated for the purpose of operating temperature optimization of the engine. The engine output increases almost linearly as the heating water temperature (TH) rises. On the other hand, the engine output shows a gradual decrease as the temperature of SMA element during cooling (TSMA) rises to 321.4 K and then an abrupt decrease when the TSMA = 322.7 K. Thermal cycling tests under constrained strain conditions for the SMA element were carried out to investigate the effect of heating/cooling temperatures to generation stress (Δσ) and reaction velocity (VR) of the SMA element. In result, Δσ increases gradually with the increase of TH. Besides, VR increases almost linearly as TH increases. This result suggests that the increase of engine output as TH increases is mainly due to the increase of the VR. Meanwhile, VR increases gradually with the increase of TSMA. Besides, Δσ increases as TSMA rise up to 318 K, above which it decreases rapidly. From these results, it may be concluded that the contributing factor to the engine output is the variation of Δσ and VR with the variation of TSMA.

  • Hayato Nakasawa, Tomohisa Takamatsu, Yoshihiko Iijima, Kei Hayashi, Yu ...
    2018 年 43 巻 2 号 p. 85-91
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    The thermoelectric properties of Mo and Ge co-substituted CrSi2 have been investigated. Polycrystalline samples of (Cr1−xMox)Si2 (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.10) and (Cr0.92Mo0.08)(Si1−yGey)2 (y = 0, 0.01, and 0.02) were prepared by the two-step arc-melting method followed by spark plasma sintering and annealing. Powder X-ray diffraction confirmed that single-phase (Cr1−xMox)(Si1−yGey)2 samples were obtained. Mo and Ge co-substitution in CrSi2 resulted in both an increase in the power factor and a large decrease in the thermal conductivity, which resulted in a high figure-of-merit (zT) value for the (Cr0.92Mo0.08)(Si0.99Ge0.01)2 sample (zT = 0.29 at 700 K). This zT value is the highest reported value for CrSi2-based thermoelectric materials.

  • Yasuhiro Yoneda, Ryo-ichi Kunisada, Tsukasa Chikada, Shintaro Ueno, Ko ...
    2018 年 43 巻 2 号 p. 93-96
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    KNbO3 nanocrystals were grown by solvothermal technique assisted by a microwave treatment. The morphology of nanocrystals is a cubic shape and the crystal structure is also cubic system. This is an ideal case for the so-called Sherrer's equation. We performed high- energy X-ray scattering to extract various structural parameters. The particle size can be evaluated by the Sherrer's equation. The unit cell size of the KNbO3 nanocrystals was reduced as the particle size increased. The local structure of the nanocrystals was found to be a rhombohedral structure similar to that of the bulk KNbO3. Although the periodic structure of the perovskite system unchanged locally, the first-nearest neighbor and the second-nearest neighbor bond distances corresponding to Nb-O and K-O was changed as the particle size increased.

  • Yuki Egami, Hata Soichiro, Seiken Kato, Sho Yamamoto, Toru Nonami
    2018 年 43 巻 2 号 p. 97-100
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    In this study, the phosphorus adsorption ability of natural diopside in an aqueous solution of phosphoric acid was evaluated. The influence of calcium ions present in the aqueous solution and pH on the phosphorus adsorption capacity of diopside was investigated. Diopside was found to adsorb a significant amount of phosphorus in the calcium-rich solution. In addition, its phosphorus adsorption ability tended to improve in aqueous solutions with lower pHs. In such solutions, calcium was eluted to a large extent from diopside. The adsorption rate of phosphorus in an aqueous solution of diopside was highly correlated to calcium elution. For solutions with low pH, the calcium bound to the OH group interacts with H+ and the charge on diopside becomes more positive. With this increasing positive charge, it can more effectively adsorb the negatively charged phosphate ions. It was assumed that calcium reacts with the phosphate ions and forms calcium phosphate on the diopside surface. The amount of phosphorus adsorption is related to the elution of calcium from diopside. We also found that natural diopside could be used as a phosphorus adsorbent in aqueous solutions without the need for adding calcium or adjusting pH.

  • Ten Sugimoto, Kinya Kawamura, Takuya Kawaguchi, Takashi Tsuchiya, Chiz ...
    2018 年 43 巻 2 号 p. 101-104
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    Amorphous WO3-x thin films with ~200 and ~600 nm thicknesses have been prepared on Pt/SiO2 substrates by RF magnetron sputtering. The mixed valence states of W6+ and W5+ are observed in the photoemission spectroscopy (PES) spectra of W 4d core level. The electrical conductivities exhibit the thermal activation-type behaviors in the temperature region of 100~200°C. The activation energies of 200 and 600 nm films are 0.1 and 0.6 eV, respectively. The band gaps (Eg) of 200 and 600 nm films are ~2.6 and ~2.0 eV, respectively. The expanded PES in the Eg region and X-ray absorption spectra exhibit the W 5d-DOS at the Fermi level and defect-induced state at the bottom of conduction band, respectively. The above results indicate that the conducting carrier of amorphous WO3-x thin film is closely related to the film thickness and oxygen vacancies.

  • Kazuki Kikuchi, Masafumi Kobune, Takeyuki Kikuchi, Tsubasa Migita, Yus ...
    2018 年 43 巻 2 号 p. 105-108
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    Ferromagnetic cobalt ferrite (CoFe2O4) thin films for magnetoelectric multiferroic applications were synthesized on (Bi3.25Nd0.65Eu0.10)Ti3O12/Nb:TiO2 substrates at reaction temperatures of 140-190°C using a non-aqueous sol-gel process. The magnetic properties of the films were measured, and the sample synthesized at 180°C was found to exhibit the highest residual magnetization and coercivity of 1.5 emu/g and 134 Oe, respectively. The ferroelectric properties of all samples were similar, with a large remanent polarization of 58-67 μC/cm2 and a coercive field of 421-462 kV/cm, regardless of the reaction temperature. Based on its magnetic and ferroelectric properties, the sample synthesized at 180°C has potential as a practical multiferroic material.

  • Jun Kawakami, Yui Kinami, Masahiro Takahashi, Shunji Ito
    2018 年 43 巻 2 号 p. 109-112
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    2-Hydroxy-1-tryptanthrin (T2OH) and 1-formyl-2-hydroxytryptanthrin (T2OH1CHO) were synthesized as fluorescent metal-ion sensors and near-infrared fluorescent labeling reagents. T2OH was well suited for use as a fluorescent chemosensor for Cu2+ and Al3+ in an acetonitrile solution, and as a near-infrared fluorescent (λf, max > 650 nm) labeling reagent. However, it was unable to detect changes in a surrounding aqueous environment (DMSO/H2O = 1/9, v/v). Meanwhile, T2OH1CHO was well suited for use as a fluorescent chemosensor for Al3+ in acetonitrile and aqueous solutions.

  • Kunio Funakoshi, Yusuka Imaya
    2018 年 43 巻 2 号 p. 113-115
    発行日: 2018/04/01
    公開日: 2018/04/01
    ジャーナル フリー

    Hydroxyapatite (HAp) crystals adsorb the many kinds of inorganic and organic compounds and HAp – adhered anatase titanium dioxide, TiO2, photocatalysts excel in the oxidizing abilities, rather than anatase TiO2 photocatalysts. The quantitative evaluation about the electrochemical properties of HAp crystals is, however, not discussed. In this study, the oxidation - reduction potentials (ORP) of the suspended solution for HAp - adhered anatase TiO2 photocatalysts and anatase TiO2 ones were measured by an ORP meter and the roles of HAp crystals to photocatalytic reactions of anatase TiO2 photocatalysts were discussed. The maximum ORP differences of suspended solutions for the case of anatase TiO2 photocatalysts were higher than those for HAp – adhered anatase TiO2 photocatalysts. The decreasing rates of the ORP differences for the case of HAp – adhered anatase TiO2 photocatalysts were slower than those for anatase TiO2 photocatalysts. When UV light is irradiated to HAp – adhered anatase TiO2 photocatalysts, electrons produced by photocatalytic reactions on anatase TiO2 photocatalysts transfer to HAp crystals, and then they are stored in HAp crystals. Moreover, their electrons transfer from HAp crystals to anatase TiO2 photocatalysts and the oxidation reactions occur on anatase TiO2 photocatalysts in the dark.

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