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Chemical Analysis and Electronic Structure Studies of Vacancy-Type Defects by Measuring Positron Annihilation Momentum Distribution in Wide Range

Research Project

Project/Area Number 10450229
Research Category

Grant-in-Aid for Scientific Research (B).

Allocation TypeSingle-year Grants
Section一般
Research Field Physical properties of metals
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

HASEGAWA Masayuki  TOHOKU UNIVERSITY, INSTITUTE FOR MATERIALS RESEARCH, PROFESSOR, 金属材料研究所, 教授 (80005975)

Co-Investigator(Kenkyū-buntansha) YUBUTA Kunio  TOHOKU UNIVERSITY, INSTITUTE FOR MATERIALS RESEARCH, RESEARCH ASSOCIATE, 金属材料研究所, 助手 (00302208)
TANG Zheng  TOHOKU UNIVERSITY, INSTITUTE FOR MATERIALS RESEARCH, RESEARCH ASSOCIATE, 金属材料研究所, 助手 (80271972)
NAGAI Yasuyoshi  TOHOKU UNIVERSITY, INSTITUTE FOR MATERIALS RESEARCH, RESEARCH ASSOCIATE, 金属材料研究所, 助手 (10302209)
Project Period (FY) 1998 – 2000
Project Status Completed (Fiscal Year 2000)
Budget Amount *help
¥12,000,000 (Direct Cost: ¥12,000,000)
Fiscal Year 2000: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1999: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 1998: ¥6,400,000 (Direct Cost: ¥6,400,000)
KeywordsPositron Annihilation / BCC-Cu / Nano-particles / Fermi Surface / Reactor Pressure Vessel Steels / Fe-Cu / Al-Cu-Mg / Magic Number Vacancy Clusters / 電子運動量分布 / 黒鉛 / シリコン / 空孔クラスター / 酸素-空孔複合体 / 酸素極性基 / 原子空孔 / 魔法数 / 空孔・不純物
Research Abstract

We have measured electron momentum distributions in wider ranges sampled by positrons in several metals and semiconductors using positron annihilation techniques of two dimensional angular correlation of annihilation radiation (2D-ACAR) and coincidence Doppler broadening (CDB). Marked results are as follows.
1) Fe-Cu model alloys for nuclear reactor pressure vessel (RPV) steels containing harmful Cu impurities.
A quantum-dot-like positron state is demonstrated in the defect-free Cu ultrafine particles embedded in Fe matrix. The wave functions of all positrons are entirely confined in the particles. The positrons in this state convey us usefu and exclusive information about the atomic and electronic structures of the particles. By 2D-ACAR experiments on Fe-1.0%Cu single crystals, we have determined the Fermi surface of BCC Cu ultrafine particles in Fe. The Fermi surface is almost spherical but has 12 necks around the centers of (110) Brillouin faces of the BCC structure.
In neutron-irradiated Fe-Cu model alloys, we have observed irradiation-induced microvoids of which inner surfaces are almost coated with Cu atoms. After annealing around 4O0℃, the dissociation of vacancies from the microvoids leads to the formation of Cu ultrafine particles.
2) Role of vacancy-solute complex in the initial rapid age hardening in Al-Cu-Mg alloy.
Using CDB method, we have found that quenched-in vacancies are bound to Mg atoms rather than Cu atoms initially and the vacancy-Mg complexes easily migrate to vacancy sinks at 150℃. Vacancy-Mg-Cu complexes form during the initial 1 min aging at vacancy sinks. The dislocation-solute interaction is the origin of the initial rapid hardening.
3) Mgic number vacanvy clusters in graphite and Si.
By combining positron annihilation experiments and first-principles calculation, we firstly observed magic number vacancies in a covalent-bond materials : graphite after neutron irradiation.

Report

(4 results)
  • 2000 Annual Research Report   Final Research Report Summary
  • 1999 Annual Research Report
  • 1998 Annual Research Report
  • Research Products

    (26 results)

All Other

All Publications (26 results)

  • [Publications] Y.Nagai et al.: "Role of Vacancy-Solute Complex in the Initial Rapid Age Hardening in an Al-Cu-Mg Alloy"Acta Mater.. 59. 911-918 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Y.Nagai et al.: "An Origin of Embrittlement of Reactor Pressure Vessel Steels : Ultra-fine Cu Precipitates"Phys.Rev.B. 63(in press). (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Y.Nagai et al.: "Positron confinement in ultrafine embedded particles : Quantum-dot-like state in Fe-Cu"Phys.Rev.B. 61. 6574-6578 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] M.Hasegawa et al.: "Positron and Positronium Studies of Irradiation-induced defects and microvoids in vitreous and metamict silica"Nucl.Instr.Meth.in Phys.Res.B. 166-167. 431-439 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Z.Tang et al.: "Stable Vacancy Clusters in Neutron-Irradiated Graphite : Evidence for Aggregations with a Magic Number"Phys.Rev.Lett.. 82. 2532-2535 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Z.Tang et al.: "Electron Momentum Distributions in elemental semiconductors proved by positrons"Phys.Rev.B. 57. 12219-12228 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Y.Nagai, M.Murayama, Z.Tang, T.Nonaka, K.Hono and M.Hasegawa: "Role of Vacancy-Solute Complex in the Initial Rapid Age Hardening in an Al-Cu-Mg Alloys"Acta Mater.. 59. 911-918 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Y.Nagai, Z.Tang, M.Hasegawa, T.Kanai and M.Saneyasu: "An Origin of Embrittlement of Reactor Pressure Vessel Steels : Ultra-fine Cu Precipitates"Phys.Rev.. B63. 134110/1-5 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] C.L.Wang, Y.Kobayashi, W.Zheng, C.Zhang, Y.Nagai and M.Hasegawa: "Positronium Formation in a Polymer Blend System Consisting of Polyethylene and Chlorinated Polyethylene"Phys.Rev.. B.63. 064204/1-9 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Y.Nagai, M.Hasegawa, Z.Tang, A.Hempel, K.Yubuta, T.Shimamura, Y.Kawazoe, K.Kawai and F.Kano: "Positron confinement in ultrafine embedded particles : Quantum-dot-like state in Fe-Cu"Phys.Rev.. B61. 6574-6578 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] M.Hasegawa, M.Saneyasu, M,Tabata, Z.Tang, Y.Nagai, T.Chiba and Y.Ito: "Positron and Positronium Studies of Irradiation-induced defects and microvoids in vitreous and metamict silica"Nucl.Instr.Meth. in Phys.Res.. B166-167. 431-439 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Z.Tang, M.Hasegawa, T.Shimamura, Y.Nagai, T.Chiba, Y.Kawazoe, M.Takenaka, E.Kuramoto, and T.Iwata: "Stable Vacancy Clusters in Neutron-Irradiated Graphite : Evidence for Aggregations with a Magic Number"Phys.Rev.Lett.. 82. 2532-2535 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Y.Nagai, T.Nonaka, M.Hasegawa, Y.Kobayashi, C.L.Wang, W.Zheng and C.Zhang: "Direct evidence of positron trapping at polar groups in a polymer-blend system"Phys.Rev.. B60. 11863-11866 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Z.Tang, M.Hasegawa, T.Chiba, M.Saito, H.Sumiya, Y.Kawazoe and S.Yamaguchi: "Electron Momentum Distribution in elemental semiconductors proved by positrons"Phys.Rev.. B57. 12219-12228 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Y.Nagai et al.: "Role of Vacancy-Solute Complex in the Initial Rapid Age Hardening in an Al-Cu-Mg Alloy"Acta Mater.. 59. 911-918 (2001)

    • Related Report
      2000 Annual Research Report
  • [Publications] Y.Nagai et al.: "An Origin of Embrittlement of Reactor Pressure Vessel Steels : Ultra-fine Cu Precipitates"Phys.Rev.B. 63(in press). (2001)

    • Related Report
      2000 Annual Research Report
  • [Publications] M.Hasegawa et al.: "Magic Number Vacancy Clusters in Graphite and Silicon"(in press).

    • Related Report
      2000 Annual Research Report
  • [Publications] Y.Nagai et al.: "Positron confinement in ultrafine embedded particles : Quantum-dot-like state in Fe-Cu"Phys.Rev.. 61. 6574-6578 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] M.Hasegawa et al.: "Positron and Positronium Studies of Irradiation-induced defects and microvoids in vitreous and metamict silica"Nucl.Instr.Meth.in Phys.Res.B. 166-167. 431-439 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Y.Nagai et al.: "Chemical Analysis of Precipitates in Metallic Alloys Using Coincidence Doppler Broadening of Positron Annihilation Radiation"Rad.Phys.Chem.. 58. 737-742 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] 唐政,長谷川雅幸,永井康介 他6名: "Stable Vacancy Clusters in Neutron-Irradiated Graphite: Evidence for Aggregations with a Magic Number"Physical Review Letters. 82・12. 2532-2535 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] 永井康介,長谷川雅幸 他5名: "Direct Evidence of Positron Trapping at Polar Groups in a Polymer-Blend System"Physical Review. B60・17. 11863-11866 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] 長谷川雅幸,唐政,永井康介 他4名: "Positron and Positronium studies of irradiation-induced defects and microvoids in vitreous and metamict silica"Nucleor Instruments and Methods in Physical Research B. (印刷中). (2000)

    • Related Report
      1999 Annual Research Report
  • [Publications] 永井康介,唐政,長谷川雅幸: "Chemical Analysis of Precipitates in Metallic Allys Using Coincidence Doppler Broadening of Positron Annihilation"Racliction Physics and Chemistry. (印刷中). (2000)

    • Related Report
      1999 Annual Research Report
  • [Publications] 唐政、長谷川雅幸 他5名: "Electron momentum distributions in elemental semicondutcors probed by positrons" Physical Review B. 57・19. 12219-12228 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] 唐政、長谷川雅幸 永井康介 他6名: "Stable vacancy clusters in nautron-irradiated graphite:Evidence for aggregations with a magic number" Physical Review Letters. 82・13(3月29日号掲載予定). (1999)

    • Related Report
      1998 Annual Research Report

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Published: 1998-04-01   Modified: 2016-04-21  

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