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Study of Oxygen-Exchange Mechanism Between Fine Grain Surfaces of Alkali Earth Oxides and CO Gas

Research Project

Project/Area Number 01550017
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Applied materials
Research InstitutionNara University of Education

Principal Investigator

HUZIMURA Ryoiytiro  Nara University of Education, Faculty of Education, Professor, 教育学部, 教授 (30031537)

Co-Investigator(Kenkyū-buntansha) MATSUMURA Keiko  Nara University of Education, Faculty of Education, Associate Professor, 教育学部, 助教授 (20031560)
YAMABE Shinichi  Nara University of Education, Faculty of Education, Associate Professor, 教育学部, 助教授 (00109117)
YANAGISAWA Yasunori  Nara University of Education, Faculty of Education, Associate Professor, 教育学部, 助教授 (90031591)
Project Period (FY) 1989 – 1990
Project Status Completed (Fiscal Year 1990)
Budget Amount *help
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1990: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1989: ¥1,000,000 (Direct Cost: ¥1,000,000)
KeywordsOxygen-isotope exchange / Magnesium oxide surfaces / Carbon monoxide absorbate / Alkaliearth oxides / Step sites / 酸化マグネシウム / 一酸化炭素吸着 / MgO微粒子表面 / 一酸化炭素 / ステップサイト
Research Abstract

In this study we have found that Thermal Desorption (TD) of CO^<16> takes place after adsorption of CO^<18> gas on powders of alkali earth oxides and the oxygen exchange mechanism is explained as follows.
1. For MgO, CO-TD occurs at temperatures 200, 400 and 600K and the exchange ratio (R=the ratio of the CO^<16> peak intensity to the sum of intensities of CO^<16> and CO^<18>) amounts to 0.65 even in the low temperature peak and 0.8-0.9 in the peaks above room temperature. The R values decrease with the increase of CO^<18> exposure, to a more extent for the oxide baked at higher temperatures in high vacuum. Electron microscopic observation suggests more complicated surface structures for this oxide.
2. Ab initio MO calculations assuming MgO surface clusters suggests that a single point vacancy on a plane surface is inactive for the exchange. An oxygen vacancy on a <111>-directed step boundary between Mg(111) and O(111) surfaces can provide a way to form a CO_3-type bridged intermediate to induce the exchange.
3. The R values of CaO and SrO are near to that of MgO although slight differences in TD profiles are found. For comparison we studied TD's from TiO_2 and ZnO in which peaks with R<approximately equal>O were found while we observed that from NiO with almost same magnitudes of R as MgO.
4. From above results we conclude that the oxygen-isotope exchange takes place not through electronic processes but through structural changes at surface defects of the oxides.

Report

(3 results)
  • 1990 Annual Research Report   Final Research Report Summary
  • 1989 Annual Research Report
  • Research Products

    (7 results)

All Other

All Publications (7 results)

  • [Publications] 藤村 亮一郎: "Oxygenーisotope exchange between CO adsorbate and MgO surfaces" Physical Review B. 41. 3786-3793 (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] 柳沢 保徳: "Oxygen isotope exchange between O_2 adsorbate and UVーirradiated MgO surfacees" Surface Science. 242. 513-517 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] Ryoitiro Huzimura: "Oxygen-isotope exchange between CO adsorbate and MgO surfaces" Pysical Review b. Vol. 41. 3786-3793 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] Yasunori Yanagisawa: "Oxygen-isotope exchange between O_2 adsorbate and UV-irradiated MgO surfaces" Surface Science. Vol. 242. 513-517 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1990 Final Research Report Summary
  • [Publications] Ryoitiro HUZIMURA: "Oxygenーisotope exchange between CO adsorbate and MgO surfaces" Physical Review B. 41. 3786-3793 (1990)

    • Related Report
      1990 Annual Research Report
  • [Publications] Yasunori YANAGISAWA: "Oxygenーisotope exchange between O_2 adsorbate and UVーirradiated MgO surfaces" Surface Scienes. (1991)

    • Related Report
      1990 Annual Research Report
  • [Publications] 藤村亮一郎: "Oxygenーisotope exchange between CO adsorvbate and MgO surfaces" Physical Review B. 41. (1990)

    • Related Report
      1989 Annual Research Report

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Published: 1989-04-01   Modified: 2016-04-21  

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