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-tetrafluoroethylene) films using different mediaNuryanthi, N.*; Yamaki, Tetsuya; Kitamura, Akane; Koshikawa, Hiroshi; Yoshimura, Kimio; Sawada, Shinichi; Hasegawa, Shin; Asano, Masaharu; Maekawa, Yasunari; Suzuki, Akihiro*; et al.
Transactions of the Materials Research Society of Japan, 40(4), p.359 - 362, 2015/12
The ion-track grafting of a vinylbenzyl chloride (VBC) into a poly(ethylene-co-tetrafluoroethylene) (ETFE) film is necessary for preparing nanostructured hydroxide-ion-conductive electrolyte membranes. A key for success here is to obtain as high graft levels as possible (for higher conductivity) in a smaller number of tracks (for improving the other membrane properties). To this end, therefore, the effect of the medium for the VBC grafting was investigated as part of our continuing effort to optimize the experimental conditions. A 25 
m-thick ETFE film was irradiated in a vacuum chamber with 560 MeV 
Xe at different fluences, and then the grafting was performed by immersing the irradiated films in a 20vol% VBC monomer at 60
C. A medium was a mixture of water (H
O) and isopropyl alcohol (iPrOH) at different volume ratios. The degree of grafting increased as the HO content became higher, and reached a maximum in pure HO. These results can be explained by considering the well-known Trommsdorff effect, in which poor solubility of the grafted polymer in polar media leads to an increased polymerization rate probably due to a lower termination rate.
modulated by Mn substitutionYoneda, Yasuhiro; Kohara, Shinji*; Noguchi, Yuji*; Miyayama, Masaru*
Transactions of the Materials Research Society of Japan, 40(1), p.29 - 32, 2015/03
Barium titanate (BaTiO) with a high dielectric constant is widely used in the production of ceramic capacitors. However, during sintering large numbers of ionized oxygen vacancies and conduction electrons are created. Doping with manganese is one of several ways to confine the electrons to a small region. In Mn-doped BaTiO there exist three valence states for the manganese ions, Mn
, Mn
, and Mn
. The Mn is nearly exactly incorporated into Ti sites and participates in the collective motion in the lattice. We performed local structure analysis by using atomic pair-distribution function (PDF) and X-ray absorption fine structure (XAFS). Figure 1 shows the obtained PDFs for pure BaTiO and 0.5%-Mn-doped BaTiO. All data collected at room temperature. Two obtained PDF patterns are well in agreement. Mn doping has hardly affected local structure.
Arima, Tatsumi*; Idemitsu, Kazuya*; Inagaki, Yaohiro*; Kawamura, Katsuyuki*; Tachi, Yukio; Yotsuji, Kenji
no journal, ,
Molecular dynamics simulations of uranyl ion-clay-water systems were performed to investigate diffusion and sorption behaviors of uranyl ion at external surface and interlayer of clays. The simulation results showed uranyl ions are coordinated with five water molecules in free water. Uranyl ions were evaluated to adsorb on clay surface as pentaaquo species, implying outer-sphere complexation mechanisms.
Yamashita, Shinichiro; Miwa, Shuhei; Osaka, Masahiko
no journal, ,
Fission product (FP) chemistry under the LWR severe accident (SA) conditions should be deeply understood for more precise evaluation of FP release and transport behavior, which can lead to the reduction of uncertainty in the evaluation of source term issue. We have launched a new R&D program for the evaluation of FP release and transport behavior with focuses on the FP chemistry. According to this R&D program, the obtained data for the chemical form is analyzed and the FP release and transport model is to be improved, which will then be implemented into the SA-analysis code such as THALES-2.
Yoneda, Yasuhiro
no journal, ,
Atomic pair-distribution function (PDF) analysis is the method which visualizes the structure from a short- to middle-range order. It has been applied to amorphous materials and liquids in the past. It could also be used now for the crystallized materials by using a synchrotron X-ray and a pulsed neutron facilities. The deviation between the average structure obtained by the traditional crystal structure analysis, and the local structure caused by the domain configuration in ferroelectrics, magnetic materials, hydrogen-storage materials, etc. The PDF analysis is attracted as the method bridging the local and the average structures. In particular, the outline of development of research technique and applications are reviewed about the PDF analysis using synchrotron X-ray.
Hasegawa, Shin; Fukasawa, Hideyuki*; Koshikawa, Hiroshi; Chen, J.; Maekawa, Yasunari
no journal, ,
Polymer electrolyte membranes (PEMs) with high proton conductivity at low relative humidity (RH) and superior mechanical properties at high RH were required for commercialization of fuel cells. Herein, we investigated highly conducting and mechanically stable graft-type PEMs (PEEK-PEM) based on an aromatic hydrocarbon polymers, poly (ether ether ketone) (PEEK). According to the high mechanical strength, the thin PEEK-PEM (10 m) could be prepared and showed higher power generation density than that of Nafion. In addition, Hybrid PEEK-PEMs with inorganic nano-particles such as silica and almina were prepared for further mechanical reinforcement of PEEK-PEMs.
Owada, Kenji
no journal, ,
no abstracts in English
Yamamoto, Shunya; Hakoda, Teruyuki; Yamaki, Tetsuya; Shimada, Akihiko; Yoshikawa, Masahito
no journal, ,
Developments of low Pt loading catalysts and non-Pt catalysts for an oxygen reduction reaction have been required for practical use of polymer electrode membrane fuel cells. One promising non-Pt catalyst is based on the transition metal(TM)-nitrogen (N)-carbon(C) systems (TM: Fe, Co, Ni, etc.). In the present study, we prepared Fe and N doped carbon film on a glassy carbon (GC) substrate under the different presence of N gas during the pulsed laser deposition (PLD). The ORR activity of the films was electrochemically determined using a rotating disk electrode system. The ORR activity of Fe-N-C films increased with increasing N gas pressure during the deposition. The Fe-N-C film prepared at 800C under the 5 torr of N gas pressure showed high ORR activity; its ORR potential was 0.75 V (vs. NHE). Furthermore, XPS results suggest that the ORR activity of Fe-N-C relates to the N atoms which were connected to three C atoms (graphitic-N).
Onoda, Shinobu; Oshima, Takeshi; Teraji, Tokuyuki*; Jelezko, F.*; Isoya, Junichi*; Ito, Hisayoshi
no journal, ,
no abstracts in English
Maekawa, Yasunari
no journal, ,
Yamaki, Tetsuya
no journal, ,
Researchers at Japan Atomic Energy Agency (JAEA) have been intensively working on quantum beam technology for the development of proton-conductive membranes for PEMFCs since 2001. My presentation deals with the application of high-energy heavy ion beams from the cyclotron accelerator of Takasaki Ion Accelerators for Advanced Radiation Application (TIARA), JAEA. Our strategic focus is centered on using nano-scale controllability of the ion-beam processing; the membrane preparation involves (1) the irradiation of commercially-available base polymer films with hundreds of MeV ions, (2) graft polymerization of vinyl monomers into electronically-excited parts along the ion trajectory, called latent tracks, and (3) sulfonation of the graft polymers. The resulting membranes were compared with those prepared by the conventional 
-ray-induced grafting in terms of membrane nanostructures, proton conductivity, and other properties.
Yoshimura, Kimio; Koshikawa, Hiroshi; Yamaki, Tetsuya; Shishitani, Hideyuki*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari
no journal, ,
Anion-conducting electrolyte membrane fuel cells (AEMFCs) especially in direct hydrazine fuel cells have recently received considerable attention. Due to high temperature and highly basic operating condition, it is required to develop alkaline durable AEMs. In this work, we synthesized the AEM based on a 4(5)-vinylimidazole (4VIm) monomer by radiation-induced grafting and subsequent 
-alkylation and ion exchange reactions (
) because 4VIm does not possess 
-protons, leading to a Hoffman elimination reaction, which is the main degradation route in 1-vinylimidazolium-grafted AEM (
). The alkaline stability of AEMs was estimated by monitoring the change in conductivity of AEMs in 1 M KOH at 60C. As a result, the conductivity of suddenly decreased within few hours, while the initial decrement of conductivity of was clearly suppressed. It clearly showed that the prevention of a Hoffman elimination reaction enhanced the alkaline durability of the imidazolium-type AEM.
