Transactions of the Materials Research Society of Japan
Online ISSN : 2188-1650
Print ISSN : 1382-3469
ISSN-L : 1382-3469
Volume 38 , Issue 3
Showing 1-39 articles out of 39 articles from the selected issue
Regular Papers
  • Hironori Itoh, Hideyuki Okamura, Chihiro Nakamura, Maiko Mimura, Takas ...
    2013 Volume 38 Issue 3 Pages 337-340
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    The cutting loss of Si ingot in conventional manufacturing process of Si wafers for solar cells is one of the main obstacles to reduce the cost of solar power generation. Growth of Si crystals without the cutting process is possible using substrates repelling Si melt. In this study, the porous ceramic substrate repelling Si melt was successfully developed and spherical Si and Si sheet crystals were directly prepared using this substrate. Effect of cooling rate on the quality of grown spherical Si crystals was also investigated. Spherical Si crystals consist of less than three grains were stably grown with cooling rate less than 100 K/h when the undercooling of Si melt was estimated to be 40 K. Slow cooling of Si melt on the substrate leads to low undercooling of Si melt that enables the growth of high quality spherical Si crystals. Carbon and oxygen concentration in the grown Si sheet crystal was below the specification value of Si for solar cells. Sticking or infiltration of Si against the substrate was not observed after the growth of Si crystals so the developed substrate is reusable multiple times.
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  • H. Okamura, M. Mimura, M. Nagai, H. Itoh, R. Komatsu
    2013 Volume 38 Issue 3 Pages 341-344
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
      Scorodite crystals have been paid much attention to immobilize (insolubilize) arsenic. In this paper, new synthesis method of scorodite crystals has been investigated and scorodite crystals have been successfully grown for the first time by photocatalysis method using UV light irradiation. Formation behavior of scorodite crystals with UV light irradiation was also examined and compared with the method of O2 gas injection.
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  • K. Kasatani, M. Kakuichi, Y. Morita, H. Okamoto, Y. Suzuki, J. Kawamat ...
    2013 Volume 38 Issue 3 Pages 345-348
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Fluorescence behavior of nanoparticles of two aromatic compounds, 2-ethylanthracene and pyrene, was studied. Doped nanoparticles were also studied. Transparent organic nanoparticles dispersed in water were prepared by reprecipitation method. Polyvinyl alcohol was added in water to improve stability of organic nanoparticles. Fluorescence spectra and fluorescence quantum yields were measured by an absolute photoluminescence quantum yield measurement system. Fluorescence lifetimes were measured with a combination of a femtosecond Ti:sapphire laser and a streak camera. Fluorescence behavior of 2-ethylanthracene nanoparticles doped with naphthacene, pyrene nanoparticles doped with perylene, and polycrystals of 2-ethylanthracene and pyrene, was measured. Doping of nanoparticles with dopant quenched fluorescence of nanoparticles and strong fluorescence of dopant was observed. Fluorescence quantum yield of 2-ethylnaphthacene nanoparticles doped with naphthacene and that of pyrene nanoparticles doped with perylene were as high as 0.52 and 0.58, respectively.
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  • M. Eguchi, K. Baba, K. Iwasawa, M. Nishitani-Gamo, T. Ando
    2013 Volume 38 Issue 3 Pages 349-352
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    A fibrous carbon material has been used as the catalyst support of a polymer electrolyte fuel cell (PEFC) that is called Marimo carbon (MC). The Marimo carbon has a sufficient space volume between the each fiber without any fine pores. The Marimo carbon supported Pt catalyst (Pt/MC) should show a performance different from the traditional catalyst. The Pt/MC has a better performance than the traditional catalyst when the ionomer content is less than 15.5 wt% in the catalyst layer. The traditional catalyst needs about 25 wt% ionomer for optimal performance. By using the Marimo carbon, we simultaneously succeeded in increasing the cell performance and reducing the Pt catalyst and ionomer in the catalyst layer.
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  • Akio Ohta, Hideki Murakami, Seiichiro Higashi, Seiichi Miyazaki
    2013 Volume 38 Issue 3 Pages 353-357
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    We have studied the chemical bonding features and electronic states of ultrathin Hf-La oxide using high-resolution x-ray photoelectron spectroscopy (XPS). 6 nm-thick Hf-La oxides with different La/(Hf+La) content were prepared on wet-chemical cleaned p-type Si(100) and Pt layer by thermal decomposition of Hf(DPM: dipivaloymcthanato)4 and La(DPM)3 in O2 ambient at 450℃. From XPS core-line analysis, diffusion and incorporation of Si atoms from the Si substrate into the Hf-La oxide film by 800℃ annealing in O2 ambience were pronounced with increased La content over 35%. The energy band profile of the Hf-La oxide/Si system as a function of La content has been determined by a combination of oxide bandgap (Eg) values and valence band (VB) line-ups. The conduction band (CB) offset has been also estimated using the Eg of the Si substrate, measured Eg, and VB offset. The impact of Si incorporation into Hf-La oxide on CB and VB offsets between the Hf-La(:Si) oxide and Si substrate also discussed in comparison to the energy band diagram of the Hf-La oxide/Pt structure.
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Review Papers
  • Kazuki HAYAKAWA, Takayoshi YAGASAKI, Hitoshi KOHRI
    2013 Volume 38 Issue 3 Pages 359-362
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    The engineered biodegradable plastics polylactic acid (PLA) and polybutylene succinate (PBS) were irradiated by an ion beam under argon gas and subsequently observed by atomic force microscopy. The PLA and PBS substrates were found to have smooth surfaces after ion beam irradiation with an accelerating voltage of 5 keV. The decomposition rate of the ester group, identified by Fourier transform infrared spectroscopy, increased with increasing acceleration voltage. The quantity of carbide, identified by Raman spectroscopy, was also found to increase with increasing accelerating voltage. It was difficult to observe the D peak. Based on the above results, it was concluded that the carbonization layer (self-carbonization layer) obtained mainly composed of graphite. A Ti thin film was added to the test specimen surface by ion beam mixing, forming a self-carbonization layer, and its adhesion was analyzed by performing a scratch test. High adhesion was obtained at an accelerating voltage of 5 keV. Similar results were obtained for PBS, which has low heat resistance.
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  • M. A. Guziak, T. Nishizaki, Y. Honma, K. Watanabe, T. Sasaki
    2013 Volume 38 Issue 3 Pages 363-367
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    We report on the method of enhancement of the electrical conductivity of poly(3,4-ethylene dioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) films through a treatment with newly found organic additives, such as ethylene carbonate (EC) and ethylene sulfite (ES). Addition of these secondary dopants to PEDOT:PSS aqueous solution and subsequent film preparation resulted in conductivity enhancement by three orders of magnitude. Electrical resistivity of EC (3.1 mΩcm) and ES (2.9 mΩcm) added PEDOT:PSS films are comparable with previously reported secondary dopant, such as dimethyl sulfoxide (DMSO) (2.8 mΩcm). The temperature dependence of electrical resistivity of EC, ES and DMSO added PEDOT:PSS films indicates 3D-varible range hopping (VRH) conduction. Improving the electrical conductivity, however, we need to consider a crossover from VRH to metallic conduction at low temperature.
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Regular Papers
  • Kazuhiro Kudo, Daisuke Tsutsumi, Hiroshi Yamauchi, Shigekazu Kuniyoshi ...
    2013 Volume 38 Issue 3 Pages 369-372
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Vertical-channel organic field-effect transistors (SVC-OFET) having a very short channel length formed at step-edge are fabricated by a self-aligned process. The carriers flow the vertical direction in the short channel along of the step-edge structure. SVC-OFETs showed excellent device performances with a high current and high cutoff frequency of approximately 2 MHz, which is a very high value as organic transistors. We demonstrate that the SVC-OFET has advantages for an active antenna of flexible information tag and active-matrix display applications. The fabrication process and device characteristics of SVC-OFETs are described. Furthermore basic performances of an active antenna system using SVC-OFETs are discussed.
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  • Yusuke Funatsu, Akinari Sonoda, Masahiro Funahashi
    2013 Volume 38 Issue 3 Pages 373-375
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    In this study, we designed a ferroelectric liquid crystalline semiconductor. A phenyterthiophene derivative having a double bond at the terminal of the side chain was synthesized using the Suzuki coupling reaction. This compound exhibits chiral smectic C and ordered smectic phases. In the chiral smectic phase, the spontaneous polarization reaches around 100 nC cm-2. Hole mobility in the phase is also determined to be 3 × 10-4 cm2 V-1 S-1 by a time-of-flight technique.
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  • Tsutomu Sonoda, Setsuo Nakao, Masami Ikeyama, Takuya Fujima, Takahiro ...
    2013 Volume 38 Issue 3 Pages 377-379
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    The synthesis of chromium oxycarbide thin films by reactive sputtering with carbon dioxide gas was examined in order to investigate the effects of such processing parameters on the formation of the chromium oxycarbide. The deposition of Cr-C-O films onto silicon substrates was carried out in the gas mixture of argon and carbon dioxide at the pressure of 0.5Pa by reactive DC sputtering of a chromium target with DC power of 250W. The gas flow rate of the Ar/CO2 was 7 sccm (standard cubic centimeter per minute)/ 3 sccm. For the investigation on the effects of substrate temperature, the reactive sputtering was performed with the substrates heated at various temperatures ranging from 370 to 450 degree Celsius. Under visual observation, the obtained Cr-C-O films appeared to be uniform and adhesive, and their color tone was metallic black. According to electron probe microanalysis (EPMA), it was found that the films were of oxygen-rich composition comparing with the stoichiometric chromium oxycarbide. Based on XRD, it was found that the crystallinity of chromium oxycarbide [Cr(C,O)] phase in the films depended on the substrate temperature, and assumed that the optimum temperature for the formation of the phase was about 400 degree Celsius in the examined range. Furthermore, the lowest electrical resistivity was also obtained for the film deposited at 400 degree Celsius, finding that it was approximately 10mΩcm.
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  • Masato Oda
    2013 Volume 38 Issue 3 Pages 381-383
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    We investigate the electronic structures and absorption spectra of a phenylalanine on H-terminated C(111) surfaces. It is shown that the state originates from a lowest unoccupied molecular orbital (LUMO) of phenylalanine is localized and its energy level is located at the middle of the band gap of C(111) substrate, while the state originates from a highest occupied molecular orbital (HOMO) is buried in the valence band of the substrate. Comparing the absorption spectra of the non-adsorbed substrate with the phenylalanine-adsorbed substrate, we reveal that the selective excitation of an electron from the substrate to the LUMO of phenylalanine is possible. These results indicate that we can effectively ionize a phenylalanine on diamond surfaces.
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  • M. Muhibbullah, M. Golam Mowla Choudhury, Sharif M. Mominuzzaman, Juni ...
    2013 Volume 38 Issue 3 Pages 385-388
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
      In a semiconductor, the average lifetime of the minority carriers is important for the applications of optoelectronic devices. Longer and shorter average lifetimes are expected for different applications. Photo-electrochemical measurement shows electrical and optical properties with some information of average lifetime of the minority carriers. An equation of the average lifetime for excited minority carriers in the semiconductors is derived from the results of photo-electrochemical measurement.
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  • Y. Kimishima, K. Shimada, D. Ota, M. Uehara, M. Ishii
    2013 Volume 38 Issue 3 Pages 389-392
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Room temperature ferromagnetism was observed in the rutile-type SnO2 by mechanical milling (MM). XRD results showed that the particle diameter d of SnO2 powder was 22-32 nm after MM. Magnetization measurement showed that saturated magnetization Ms at 300K was 7.8×10-2, 4.6×10-1 and 6.0×10-1 emu/mol for the milled samples at 100, 200 and 300 rpm, respectively. The oxygen vacancies may be produced on the surface of SnO2 nano-particles by the MM above 100 rpm for 15 minutes.
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  • N. Tsunekawa, K. Makihara, M. Ikeda, S. Miyazaki
    2013 Volume 38 Issue 3 Pages 393-396
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    We have studied time evolution of spatial distribution of charges stored in one-dimensionally self-aligned double-stack of Si quantum dots (QDs), which were formed on thermally-grown SiO2 with an areal dot density as high as ~1013 cm-2, by surface potential measurements using an atomic force microscope (AFM)/Kelvin probe technique. Electron injection to and emission from the Si-QDs were initially carried out by scanning the surface with an electrically-biased AFM tip in a tapping mode. A stepwise decay in the surface potential accompanied with a gradual change in the potential profile after electron injection can be interpreted in terms that the electron transfer from the upper dot to the lower dot for a stable charged state and the propagation of electron tunneling to neighboring dots proceed simultaneously. In addition, the temporal change in the surface potential after electron extraction shows early propagation of hole tunneling to neighboring dots and progressive hole tunneling from the upper dot and the lower dot but less. These results suggest that Coulomb interaction among charged dots plays a role in the time evolution of charge distribution in the closely-arranged Si-QDs.
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  • Yuji Ikeda, Masato Senami, Akitomo Tachibana
    2013 Volume 38 Issue 3 Pages 397-404
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Electronic structures with electric currents are considered in order to investigate conductive properties of nanomaterials in detail. For this purpose, complex potentials which represent sources and sinks of electrons are considered. These complex potentials make Hamiltonian non-Hermitian generally, and hence coupled perturbed Hartree-Fock (CPHF) equations for them are required. In this study, self-energies of electrodes are considered so as to describe interactions between electrodes and a channel molecule, and a perturbation Hamiltonian which corresponds to the complex potentials is constructed based on the self-energies. The present CPHF method is discussed for the perturbation Hamiltonian. Benzenedithiol (BDT) and dihydro-benzenedithiol (DHBDT) are analyzed, and local electric current densities are obtained by using the present method. The delocalization effects of electrons appear as the change of the distribution patterns of the current densities. Conductive properties of nanomaterials are investigated in terms of local conductivities defined in rigged quantum electrodynamics. It can be found that the local conductivities around the π bond between C atoms in BDT are much larger than those around the σ bond in DHBDT.
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  • Yoshifumi Suzuki, Yoshinori Chikaura, Masami Ando
    2013 Volume 38 Issue 3 Pages 405-408
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    X-ray optics for XDFI (X-ray Dark-Field Imaging) and BFI (Bright-field imaging) have been proposed and applied to visualize X-ray refraction effects yielded in biomedical objects1). In order to clarify the spatial resolution due to a crystal analyzer in Laue geometry, a program based on the Takagi-Taupin equation was modified to be used for carrying out simulations to evaluate the spatial resolution of images coming into a Laue angular analyzer (LAA). The calculation was done with a perfect plane wave for diffraction wave-fields, which corresponded to both DFI and BFI, under the conditions of 35 keV and a diffraction index 440 for 160 and 480 μm-thick LAAs, adding to refraction effects.
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  • Kohki Mukai, Rikiya Munekata, Jun Tanaka, Satoshi Sakamoto, Seisuke Na ...
    2013 Volume 38 Issue 3 Pages 409-413
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    We report that the nickel micro parts produced via the micromolding method were highly hardened through the heat treatment. The resin mold modeled by stereolithography was replicated by nickel electroless plating to fabricate the nickel micro fastener. Vickers hardness of the nickel parts was improved to 800 HV by 200℃ heat treatment. The hardness depended on the heat-treatment temperature, and it was attributed to the result of competition between the re-crystallization of nickel and the eduction of nickel-phosphorus compound.
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  • Takako Nakamura, Tsuguyori Ohana
    2013 Volume 38 Issue 3 Pages 415-418
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    A useful method of modifying the surface of diamond powders with sulfur-containing functionalities was developed by the use of the photolysis of elemental sulfur. The sulfur-modified diamond powder exhibited a surface-attachment behavior to gold nanoparticles through the sulfur-containing linkage. In brief, the exposure of the modified diamond powders to gold colloids resulted in gold nanoparticles being attached to the diamond powders. The introduction of sulfur-containing functional groups and gold nanoparticles on the diamond surfaces was confirmed by means of XPS, DRIFT and mass spectroscopy analyses. Subsequently, the probe DNA attached onto the gold-modified diamond powder showed a DNA hybridization behavior by the treatment with a fluorescence-labeled target DNA oligonucleotide.
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  • N. Nakayama, K. Takahashi, K. Fujiwara, A. Nakatsuka, M. Isobe, Y. Ued ...
    2013 Volume 38 Issue 3 Pages 419-422
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Structural phase transitions of Li2MgSiO4 and Li2MgGeO4 at high temperature have been investigated by means of in situ high temperature powder XRD measurements. The monoclinic P21/n phase of Li2MgSiO4 shows a reversible phase transition to high temperature orthorhombic Pmnb phase due to the order-disorder of Mg and Li atoms at 590 ℃. By slow cooling from 1000℃ to room temperature, the monoclinic Pn phase of Li2MgGeO4 was obtained. Lattice parameters are a = 6.389(1), b = 5.475(1), c = 4.995(1) Å, and β = 90.18(1). The monoclinic Pn phase of Li2MgGeO4 shows a reversible transformation to the orthorhombic Pmn21 phase at 540 ℃, accompanied with the abrupt contraction along c-axis and elongation along b-axis on heating.
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  • H. Cho, M. Senju, Y. Takeda, T. Yamamoto, T. Sakuma
    2013 Volume 38 Issue 3 Pages 423-426
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Heat-engines using shape memory alloy (SMA) were expected to be employed as heat-engines driven by low-temperature thermal energy. Therefore, some trial products of heat-engines using SMA were produced and studied. However, since the inhomogeneous temperatures of the SMA element result during heating / cooling of the SMA element, the product-life cycle of conventional heat-engines using SMA becomes short. Moreover, if large power outputs are to be achieved, these engines would become large in size. Therefore, conventional SMA heat-engines have not been put into practical use. We propose a new actuator using a SMA spiral spring. By using this system, the uniform heating / cooling of the SMA element (improvement of the product life) and downsizing of the equipment are expected. Therefore, we manufactured a prototype of a heat-engine using a SMA spiral spring actuator, and the output characteristics of this heat-engine were investigated.
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  • H. Cho, D. Kotegawa, T. Sakuma, K. Yamauchi
    2013 Volume 38 Issue 3 Pages 427-431
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    The repeated heat-treatment under constrained strain is necessary for the manufacturing process of laser-cut Ti-Ni shape memory alloy (SMA) stent. In this research, the effect of applied strain during repeated heat-treatment under constrained strain on the mechanical and shape-memory properties of the Ti-Ni SMA wire was investigated. The chemical composition of the alloy is Ti-50.4at%Ni. At first, the specimen is heat-treated at 673 K for 3.6 ks. And then, heat-treatment under constrained strain, at 773 K for 0.3 ks. The applied strain at a single heat-treatment (εap) was 8 %, 10 % and 13.3 %, and the heat-treatment is repeated so as to achieve a total applied strain of 40 %. The critical stress for inducing martensite (σM) and minimum recovery stress (σmin) increases with increasing εap. However, σM of each specimen becomes constant during amplitude testing. In addition, σmin of εap=8 % and 10 % became 0 MPa during amplitude testing. Meanwhile, the σM of εap=13.3 % does not become 0 MPa during amplitude testing. Thus, the function deterioration is reduced by increasing εap. The reduction of function deterioration is caused by the increase of dislocation density with increasing εap.
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  • N. Tsubouchi, S. Shikata
    2013 Volume 38 Issue 3 Pages 431-434
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    In this paper, we report investigations on optical and electrical properties of diamond implanted with high dose (up to ~1021 cm-3) B, C, N or P at elevated temperatures in the energy range 30-175 keV and post-implantation annealed, and discuss their related band structures. It is known that the high-dose ion implantation over critical dose Dc to diamond about room temperature results in graphitization after a post-implantation annealing process. In contrast to that, it is revealed that any diamonds B-, C-, N- and P-implanted at high doses at elevated temperatures (~400 ℃) maintain diamond structures (graphitization does not occur) after annealing. In the cases of B and N, not only graphitization is avoided but also their resistivities are reduced after annealing. In the B doped sample, electrical activation of B impurity to its valence band occurs and becomes a p-type degenerate semiconductor. In the N doped sample, the resistivity is ~103 times as high as that in the B doped sample, but the value is much lower than a C implanted sample formed in this study. This suggests that in the N doped sample impurity band conduction related to nitrogen (including nitrogen-vacancy complexes) occurs unlike the B doped sample. The resistivity of the P doped sample is ~106 times as high as that of the N doped sample.
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  • Gai Tsujino, Kiyoharu Nakagawa, Hirokazu Oda, Toshihiro Ando
    2013 Volume 38 Issue 3 Pages 435-438
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Carbon nanotube was synthesized by decomposition of ethylene over oxidized diamond-supported catalysts at a relatively mild temperature. We focused inner structure of carbon nanotubes which were synthesized using Ni-Fe, Co-Fe, and Ni-Co loaded oxidized diamond catalysts. In these catalysts of Ni-Fe, Co-Fe, and Ni-Co-loaded oxidized diamond catalysts, oxidation state of loaded metals were compound oxide of NiFe2O4, CoFe2O4, and NiCo2O4, respectively. The oxidation state of loaded-bimetallic species might have played an important role in clear internal structure of synthesized carbon nanotube.
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  • M. Takeda, M. Migita, Y. Nozaki, M. Uehara, T. Kuramoto, D. Hamane, Y. ...
    2013 Volume 38 Issue 3 Pages 439-442
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Re was added into the MgB2 superconductor. The Mg, B and Re were sintered at 1173K for 30 minutes under H2/Ar atmosphere in the electric furnace. The nominal Rex(MgB2)1-x samples were prepared in 0≤x≤0.05. The field and x dependences of the critical current density Jc were analyzed by the extended critical state model. The enhancement of Jc was observed for the x = 0.02 sample. The effective pinning center should be ReB2 nano-particles on the MgB2 grain boundaries.
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  • Wataru Kada, Takahiro Satoh, Akihito Yokoyama, Masashi Koka, Tomihiro ...
    2013 Volume 38 Issue 3 Pages 443-446
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    A new microscopic imaging technique using a MeV ion microbeam probe was demonstrated for the nondestructive imaging and spectroscopy analysis of micrometer-sized targets. Visible luminescence caused from the impact of MeV ion irradiation was analyzed using a newly developed Ion-Luminescence (IL) Microscopic Imaging and Spectroscopy (ILUMIS) system based on a microbeam line of a 3 MV single-ended accelerator. Wavelength-dispersive images of IL were obtained from particulate targets with a spatial resolution of 1 μm and a wavelength resolution of 2 nm. Particular chemical state inside the target was successfully obtained through the spectroscopy of IL analysis.
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  • Toru Harigai, Koyo Iwasa, Hirofumi Koji, Noriko Nitta, Hiroshi Furuta, ...
    2013 Volume 38 Issue 3 Pages 447-450
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Nanosize fibers were formed by RF O2 plasma etching of flat diamond-like carbon (DLC) film. The DLC films were deposited on Si substrates by an RF plasma chemical vapor deposition (CVD) method and subsequently etched by the RF O2 plasma. The length (height) of nanofibers increased and the thickness of remaining bulk DLC layer decreased with increasing etching duration. It was due to 10 times difference in etching rates at the top of nanofibers and on the bottom surface of nanofibers. After disappearance of the bulk DLC layer, the length of nanofiber gradually decreased and the diameter slightly increased with increasing etching duration, and finally deformed into candle-like shapes due to sputtering and re-deposition. The effects of electrical charging up locally on the top of fibers and of unintentional contamination of Cu sputtered from electrode were considered as the mechanisms for initiation of selective etching, formation and deformation of nanofibers.
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  • Ryumon Tajima, Kenji Kamishima, Koichi Kakizaki, Nobuyuki Hiratsuka, A ...
    2013 Volume 38 Issue 3 Pages 451-454
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
      We have investigated the synthesis conditions and the magnetic properties of a new U-type hexaferrite, Ba4Cu2Fe36O60(Cu2U). The samples were prepared by a conventional ceramic method. We used BaCO3, CuO, and α-Fe2O3 as starting materials. They were mixed in a desired proportion, Ba4+xCu2Fe36O60, and synthesized at 1050℃. We found that a 10 at.% excess of barium compared with the stoichiometric composition, is the best condition for the synthesis of the U-type hexaferrite. It is also found that the saturation magnetization at room temperature is 53.5 emu/g, and the Curie temperature is about 420℃.
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  • K. Fujiwara, T. Tamaki, C. Kishimori, R. Titorenkova, A. Nakatsuka, N. ...
    2013 Volume 38 Issue 3 Pages 455-458
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Fine particles of Na-GTS have been prepared by using hydrothermal method. Co2+-exchanged GTS were obtained by shaking 0.5 g of the single-phase Na-GTS sample in the aqueous solutions of CoCl2 (25 mL, 0.025~1.0 M) at 40℃ for 24 hours. Samples with the composition 0.23 ≤ x ≤ 0.9 in the formula of Na4-4xCo2xTi4Si3O16 were obtained. With the increase of Co composition x, the rhombohedral lattice parameter a increases and α becomes close to 90°. The Co elution ratios were about 90 % for the samples with x = 0.23 and 0.56, whereas 70% for the samples of ion exchange ratio with x = 0.88. By Co2+ exchange, the water content increased from 20.5 to 24.5 % and the DTA peak temperature due to the dehydration was lowered from 253 to 230℃. FT-IR spectra showed apparent change in the absorption peaks due to the O-H stretching in the range of 3000~3600 cm-1 suggesting some change in the hydration state.
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  • T. Umegaki, Q. Xu, Y. Kojima
    2013 Volume 38 Issue 3 Pages 459-462
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
      Hollow nickel-silica composite spheres were synthesized by sol-gel based method using L(+)-arginine as a promoter for the reaction followed by in-situ activation in aqueous sodium borohydride (NaBH4)/ammonia borane (NH3BH3) solutions. The resulting powder products include hollow spheres with the diameters of 200-400 nm and wall thickness of ca. 60 nm. The evolution of 2, 53, and 58 mL hydrogen was finished in about 25, 310, and 90 min in the presence of the hollow nickel-silica composite spheres from aqueous NH3BH3 solution, aqueous NH3BH3 solution following by ex-situ activation in aqueous NaBH4 solution, and aqueous NaBH4/NH3BH3 solution, respectively. The results indicate that the in-situ synthesized hollow nickel-silica composite spheres in aqueous NaBH4/NH3BH3 solution show higher activity for hydrolytic dehydrogenation of NH3BH3 than the hollow nickel-silica composite spheres obtained in aqueous NH3BH3 solution and in aqueous NH3BH3 solution following ex-situ activation in aqueous NaBH4 solution. The evolution of 50 mL hydrogen was finished in about 100 min introducing additional aqueous NH3BH3 solution to the solution in the presence of the in-situ synthesized hollow nickel-silica composite spheres, indicating the in-situ synthesized hollow nickel-silica composite spheres have the ability for recycle use for hydrolytic dehydrogenation of NH3BH3.
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  • Quang-Duy Dao, Hitoshi Fukui, Sun Hwan Lee, Masashi Ohmori, Taishi Kum ...
    2013 Volume 38 Issue 3 Pages 463-466
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    The improvement of the photovoltaic performance of 1,4,8,11,15,18,22,25-octahexyl-phthalocyanine (C6PcH2)-based bulk-heterojunction solar cells using various fullerene derivatives was studied. By using asymmetric fullerene derivatives, the external quantum efficiency of the solar cells at around 500 nm was improved from 8% to 24%, and the short-circuit current density increased from 8.09 to 10.17 mA・cm-2. An open-circuit voltage of 0.96 V was achieved by a using fullerene derivative with a high lowest unoccupied molecular orbital. The photovoltaic properties were also discussed, taking into consideration the effects of adding the fullerene on the crystallization of C6PcH2 molecules in the hexagonal structure and the optical properties.
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  • Yasuo Kojima, Yoshiaki Kato, Hiroshi Takeda, Seung-Lak Yoon
    2013 Volume 38 Issue 3 Pages 467-471
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Changes of the extractives contents in pruning shoots of Japanese cedar during storing and pelletizing procedure were determined with GC and GC/MS. The extractives are consisted with essential oil and phenols such as terpenoids, flavonoids and lignans. Monoterpenes with high volatile properties were released from the leaves during storing and pelletizing of the pruning shoots. The remaining essential oils in the pellets were mainly consisted of sesquiterpenes, diterpenes, and some monoterpene-alcohols with lower volatility. These remaining oils are well known for having anti-biotic properties. Other extractives were also subjected to qualitative and quantitative analysis. Ethyl acetate and alcohol soluble fractions containing phenols and phenol glycosides, respectively, also remained in the pruning shoots and pellets after storage and pelletizing. These fractions exhibited anti-oxidant activity.   Pellets produced from pruning residues with varied moisture content. No correlation between moisture content and durability was detected. However, the durability did correlate with the pellet length. The durability of the pellets was slightly lower than that of the normal tree trunk pellets. In addition, the higher heating value (HHV) of the pruning residue pellets was higher than that of the normal pellets because of the higher extractive concentrations such as in terpenoids, phenols, and wax.
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  • Wariya Sirithep, Yusuke Narita, Yu Nagase
    2013 Volume 38 Issue 3 Pages 473-476
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    The syntheses of novel polyesters and poly(ester-urethane)s containing phosphorylcholine (PC) group was carried out. The obtained polymers were soluble in aprotic polar solvents such as DMSO and NMP. By the way, the copolyesters containing polycarbonate segment showed the better solubility than the homopolyester, which were soluble in the low boiling point solvents such as THF and chloroform. Furthermore, the obtained polymers showed the high thermal stability up to 250℃, at which the thermal degradation of PC moiety occurred. In particular, the self-standing polymer films could be prepared from poly(ester-urethane). The poly(ester-urethane) films exhibited the elastic properties with high tensile strength, therefore, these polymers could be expected as elastic biocompatible materials for the use of biomedical devices.
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  • Hong Guang, Masato Aoki, Shingo Tanaka, Masanori Kohyama
    2013 Volume 38 Issue 3 Pages 477-480
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Adsorption of oxygen molecule on single layer graphene with the STW defect is investigated using the density functional calculations. The physisorption and induced change in the low energy band structure are discussed in detail. A physisorbed O2 molecule on defect-free graphene acts as a hole-dopant as a result of that minority-spin O2-π* state is fractionally occupied due to hybridization with graphene π-band. In the STW defective graphene, C-C dimer at the center of the defect provides a more favorable physisorption site with more gain in adsorption energy and accordingly a stronger hopping between a minority-spin O2-π* state and π-band of graphene. We predict that the STW defect would make the O2 physisorption more tightly bound and be promoting the hole-doping in graphene.
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  • Mikihiro Nomura, Daiki Tamashiro, Shogo Sakai, Ryuhei Ono, Abudullah B ...
    2013 Volume 38 Issue 3 Pages 481-484
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Improving water flux through a zeolite membrane is important in reducing the cost of manufacturing such membranes. Water flux through a mordenite (MOR) zeolite membrane was increased by 84% by treating it with a novel ion beam irradiation technique that maintained high water permselectivity (1200). Os ions were accelerated in a cyclotron at 490 MeV, and a fluence of 3.0 × 1011 ions cm-2 was employed for treatment. A calculation using SRIM 2012 showed that the Os ion tracks at 490 MeV should be passed through the MOR zeolite layer. In this study, ion tracks of approximately φ 8 nm were measured on the surface view of the transmission electron microscope (TEM) observations. The single gas permeation of H2 and N2 at room temperature was almost the same before and after irradiation treatment. The ion track pathways through the MOR layer were water permselective assuming that all the permeation change before and after irradiation was due to the ion track paths.
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  • Kazuaki KOBAYASHI, Shojiro Komatsu
    2013 Volume 38 Issue 3 Pages 485-492
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    We have investigated the electronic and lattice properties of AlBN and related ternary polytypes which are sp3-bonded compounds. Considered polytypes are 2H-, 3H-, 4H-, 5H-, 6H-, 3×2H-, and 12H. Internal atoms (Al or N) of AlN polytypes replaced with B, P, or As atoms as AlBN, AlPN, and AlAsN. Their electronic and lattice properties are optimized automatically by the first-principles molecular dynamics (FPMD) method. Their electronic band structures are non-metallic with the exception of 2H-AlBN(Al2BN), 4H-AlAsN(Al4AsN3), 4H-AlAsN0(Al4As2N2), and 4H-AlPN(Al4PN3). Most band gaps of calculated AlBN polytypes are indirect. One 3×2H-AlBN(Al5BN6) structure has a direct band gap although the band gaps of other calculated 3×2H-AlBN are indirect.
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  • Tomoya Sato, Yoji Jimba, Hiroshi Miyazaki
    2013 Volume 38 Issue 3 Pages 493-496
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    We study the surface electromagnetic waves (SEMWs) of bi-isotropic chiral metamaterials. Phase diagrams of SEMWs are derived by combining the Maxwell equations and the constitutive relations which include chirality. Numerical results of the phase diagrams are presented for chiral metamaterial surfaces in the vacuum as functions of permittivity, permeability, and chiral parameters. It is shown that the chirality tends to change the localization lengths of SEMWs and strongly modifies the characteristic feature of the electromagnetic fields near the surface.
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  • Y. Sasajima, H. Onuki, N. Ishikawa, A. Iwase
    2013 Volume 38 Issue 3 Pages 497-502
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    The structural modification caused by the high-energy-beam irradiation of single-crystalline β-cristobalite was simulated by the molecular dynamics method. As the initial condition, high thermal energy was supplied to the individual atoms within a cylindrical region of nanometer-order radius located in the center of the specimen. The supplied thermal energy was first spent to change the crystal structure into an amorphous one within a short period of about 0.3ps, then it dissipated in the specimen. The amorphous track radius Ra was determined as a function of the effective stopping power gSe, i.e., the thermal energy per unit length created by ion irradiation. It was found that the relationship between Ra and gSe follows the relation Ra2=alog(gSe)+b. Compared to the case of Si single crystal, it was easier to produce amorphous track because of the weakness of the bonding between SiO4 tetrahedra. It was also found that the mechanism of structural transition changes at Ra = 1 nm.
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  • Naoyuki Yamasaki, Hideyuki Utsumi, Jaeki Kim, Hiroyuki Yoshida, Akihik ...
    2013 Volume 38 Issue 3 Pages 503-506
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
    Polymer main chain alignment under reciprocating shear flow to conjugated polymer films has been studied. A piezoelectric element, which generates oscillating shear stress, was employed as an actuator. Uniaxially oriented poly(3-dodecylthiophene) (P3DDT) films were fabricated by the reciprocating shearing stress. The optical and electrical anisotropies in the oriented P3DDT films were investigated and discussed by taking the polymer alignment into consideration.
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  • Yoshinao OKACHI, Kazuhiko OGAWA, Junichiro TSUJI, Toshihiro OKABE
    2013 Volume 38 Issue 3 Pages 507-512
    Published: September 01, 2013
    Released: January 17, 2014
    JOURNALS FREE ACCESS
      Development of eco-friendly drying process at biomass complex, using Japanese medical herb, was conducted in this study. It is neccessary to materialize low temperature drying in a short period of time to achieve required quality target at competitive cost without losing nutritional value. Eco-material named Woodceramics, invented in Aomori, Japan, was also known for radiation heating from far infrared rays, which is usually effective for plants drying from the inside. Woodceramics also has the properties of absorbing water and storing heat. It was applied as a drying material for Japanese traditional herb in this study. Frequent studies of possible application of Woodceramics as a heating material have been reported in the past. Because of the drying effect of far infrared rays and the other two properties with synergetic effect, we have viewed that it could be also applied as a drying unit of vegetables and grain, and their byproducts. In the first experiment, we tested the various temperature conditions to obtain optimum temperature for maintaining color, appearance and nutritional value. As a result, the quality of leaves and stalks has no deterioration even when applied at over 80℃, after adequate low temperature drying time at and around 45℃. Secondly, a test in drying stalks, which is usually the most difficult to dry, was conducted on Ashitaba, a Japanese herb, in various forms under control test such as cutting, slicing, smashing and pelleting to determine the most appropreate form for drying. Thirdly, the effect of far infrared rays of Woodceramics was tested by comparing Woodceramics burned at 500℃ and 800℃. Consequently, based on these three tests, we have discovered that the ideal process of drying Ashitaba is to start at a low temperature of 45℃ and sterilize at 80℃. We have verified that we can reduce the weight of Ashitaba by 50% and save time and energy by 30% with Woodceramics burned at 800℃, as compared to no treatment in drying in cutting pelleting form.
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