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2007 Fiscal Year Final Research Report Summary

Study of space charge and local lattice distortion in ionic conductors by artificially synthesized superlattice structures in nanometer-scale

Research Project

Project/Area Number 16074202
Research Category

Grant-in-Aid for Scientific Research on Priority Areas

Allocation TypeSingle-year Grants
Review Section Science and Engineering
Research InstitutionTohoku University

Principal Investigator

SATA Noriko  Tohoku University, Graduate Schol of Engineering, Associate Professor (20271984)

Co-Investigator(Kenkyū-buntansha) IGUCHI Fumitada  Tohoku University, Graduate School of Engineering, Assistant Professor (00361113)
NAGAO Yuki  Tohoku University, CRESS, Assistant Professor (20431520)
Project Period (FY) 2004 – 2007
Keywordssuperlattice / MBE, epitaxial / interfacial properties / fuel cells / lattice defects
Research Abstract

In this study, artificial layers are synthesized to tune dopant distribution in proton-conducting perovskite-type oxides in order to investigate influence of the dopant distribution on proton dynamics. SrZrO3 doped with trivalent rare earth metal has been chosen as a model material, as its properties of bulk crystal is well known. In this type of proton conductors, it is suggested that the dopant might have a significant effect on the proton dynamics.
The artificial layers, in which the dopant is distributed periodically in two-dimensional plane, are formed by Pulsed Laser Deposition (PLD). The host material, SrZrO3 (SZO) and the dopant layer, Y2O3 are alternately deposited on (001)MgO substrate. The thickness of SZO and Y2O3 layers are 5-20 and 0.25-1nm, respectively, and the total thickness of the film is about 200nm. HREM cross sectional views of the thin films show that very thin and flat interfacial layers of Y2O3 are formed and there is almost no difference in atomic arrangements … More between SZO and Y2O3 in HREM image, though their structure in bulk crystals are different. XRD analysis revealed that the SZO lattice is slightly distorted due to a large difference in thermal expansion coefficient. The epitaxial relationship of the artificial layer and the MgO substrate is (001)//(001) and [100]//[100].
In-plane electrical conductivity in wet air saturated with H2O and D2O at 20℃ has been obtained by impedance spectroscopy. An isotope effect is observed and it is confirmed that the main carrier in the artificial layers is proton below 400℃. It is found that the conductivity is the highest and the activation energy is the lowest when the SZO layer thickness is about 10nm. This result suggests that there is a preferable arrangement of the dopant distribution in this material, however, the conductivity was much low and the activation energy was high compared to those of bulk crystals. The electronic structures around the band gap of artificial layers are the same irrespective of the layer structure and are different from those of SZO and SZY thin films. Different mechanisms of proton conduction must be considered to elucidate the results for the artificial layers. Studies by hetero-layered structures of proton conductors might give important information to solve the problem of very low conductivity at the grain boundary region in their bulk crystals. Less

  • Research Products

    (10 results)

All 2007 2005

All Journal Article (8 results) (of which Peer Reviewed: 4 results) Presentation (2 results)

  • [Journal Article] Study of proton-conducting oxides by artificial modulation of dopant distribution2007

    • Author(s)
      D. Hondo
    • Journal Title

      Solid State Ionics 178

      Pages: 685-690

    • Description
      「研究成果報告書概要(和文)」より
    • Peer Reviewed
  • [Journal Article] Synthesis of LaO.6SrO.4FeO3/LaO.6SrO.4Co03 mixed ion conducting superlattices by PLD2007

    • Author(s)
      Noriko Sata
    • Journal Title

      SOLID STATE IONICS 178

      Pages: 1563-1567

    • Description
      「研究成果報告書概要(和文)」より
    • Peer Reviewed
  • [Journal Article] Microstructures and grain boundary conductivity of BaZrl-xYxO3 (x-0.05, 0.10, 0.15) ceramics2007

    • Author(s)
      Fumitada IGUCHI
    • Journal Title

      SOLID STATE IONICS 178

      Pages: 691-695

    • Description
      「研究成果報告書概要(和文)」より
    • Peer Reviewed
  • [Journal Article] Study of proton-conducting oxides by artificial modulation of dopant distribution2007

    • Author(s)
      D. Hondo, T. Tsurui, N. Kuwata, N. Sata, F. Iguchi, H. Yugami
    • Journal Title

      Solid State Ionics 178

      Pages: 685-690

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Synthesis of La0.6Sr0.4FeO3/La0.6Sr0.4CoO3 mixed ion conducting superlattices by PLD2007

    • Author(s)
      Noriko SATA, Kazuya IKEDA, Fumitada IGUCHI, Hiroo YUGAMI
    • Journal Title

      Solid State Ionics 178

      Pages: 1563-1567

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Microstructures and grain boundary conductivity of BaZrl-xYxO3(x=0.05, 0.10, 0.15)ceramics2007

    • Author(s)
      Fumitada Iguchi, Noriko Sata, Takao Tsurui, Hiroo Yugami
    • Journal Title

      Solid State Ionics 178

      Pages: 691-695

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Proton Transport and Microstructure Properties in Superlattice Thin Films Fabricated by Pulsed Laser Deposition2005

    • Author(s)
      N. Kuwata
    • Journal Title

      Japanese Journal of Applied Physics 44

      Pages: 8613-8618

    • Description
      「研究成果報告書概要(和文)」より
    • Peer Reviewed
  • [Journal Article] Proton Transport and Microstructure Properties in Superlattice Thin Films Fabricated by Pulsed Laser Deposition2005

    • Author(s)
      N. Kuwata, N. Sata, T. Tsurui, H. Yugami
    • Journal Title

      Japanese Journal of Applied Physics 44

      Pages: 8613-8618

    • Description
      「研究成果報告書概要(欧文)」より
  • [Presentation] Synthesis of Hetero-Interface of Proton Conducting Oxides2007

    • Author(s)
      Noriko Sata
    • Organizer
      2nd International Conference on Physics of Solid State Ionics
    • Place of Presentation
      横浜(国内)
    • Year and Date
      2007-12-18
    • Description
      「研究成果報告書概要(和文)」より
  • [Presentation] Synthesis of Hetero-Interface of Proton Conducting Oxides2007

    • Author(s)
      Noriko SATA, Mio Sakuma, Yuta Nohara, Daisuke Hondo, Yuki Nagao, Fumitada Iguchi, Takao Tsurui, Tohru Higuchi, Hiroo Yugami
    • Organizer
      2nd International Conference on Physics of Solid State Ionics
    • Place of Presentation
      Yokohama, Japan
    • Year and Date
      2007-12-18
    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2010-06-09  

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