Gas element-vacancy complexes investigated by electron momentum distribution analysis using a combination of positron annihilation and first-principles calculations
| Project/Area Number |
20K03902
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 14020:Nuclear fusion-related
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Project Status |
Completed (Fiscal Year 2022)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2022: ¥130,000 (Direct Cost: ¥100,000、Indirect Cost: ¥30,000)
Fiscal Year 2021: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000)
Fiscal Year 2020: ¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000)
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| Keywords | 陽電子寿命 / 消滅ガンマ線ドップラー広がり / 電子運動量分布 / 第一原理計算 / 原子空孔 / 欠陥複合体 / 陽電子消滅 / 電子運動量 |
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| Outline of Research at the Start |
タングステン結晶中の原子空孔（原子の抜けた孔）では、多くの研究において理論計算で予想されている陽電子寿命値に比べ20-30 ps程度短い実験値が報告されている。これは実験で観察している原子空孔には不純物ガス元素が結合していることを示唆している。本研究では陽電子捕獲サイトの空隙サイズを反映する陽電子寿命法に加え、陽電子捕獲サイト周囲の元素の違いを反映する消滅ガンマ線ドップラー広がり法を用いる。ドップラー広がりスペクトルの実験値と計算値を比較することで欠陥構造を同定し、タングステン結晶中の原子空孔で見られる陽電子寿命の実験値と計算値とのズレの原因を明らかにする。
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| Outline of Final Research Achievements |
The change in the positron lifetime of defect complexes (VXk) with multiple interstitial impurity atoms (X=H, C, N, O) bound with a vacancy in tungsten was investigated using first-principles calculations. It was found that the VH2, VC1, VN1, and VO1 complexes all exhibit a positron lifetime of around 170 ps. The Doppler broadening of the annihilation radiation spectra of these defect complexes was also calculated. It was shown that a shoulder appears around 16 mrad of electron momentum in the spectra of all defect complexes, making it difficult to distinguish the defect species. It was concluded that a combination of observation of the annealing behavior of defect complexes and calculation of the binding energy between vacancy and impurities is necessary to identify the species of these defect complexes.
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| Academic Significance and Societal Importance of the Research Achievements |
核融合炉のプラズマ対向壁材料として期待されているタングステン中の原子空孔と侵入型不純物原子との相互作用、および不純物原子の空孔への結合が陽電子寿命や陽電子消滅ガンマ線ドップラー広がりに与える影響について第一原理計算を用いて調べた。タングステン中のそのような欠陥の種類を同定するためには欠陥のアニール挙動観察と不純物原子の空孔への結合エネルギー計算の併用が必要であることが示された。
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Report
(4 results)
Research Products
(38 results)
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[Journal Article] Experimental plan for displacement damage cross sections using 120-GeV protons at Fermi National Accelerator Laboratory2022
Author(s)
Yosuke IWAMOTO, Makoto YOSHIDA, Shin-ichiro MEIGO, Katsuya YONEHARA, Taku ISHIDA, Keita NAKANO, Shin-ichiro ABE, Hiroki IWAMOTO, T. SPINA, K. AMMIGAN, N. MOKHOV, Atsushi YABUUCHI, and Toshimasa YOSHIIE
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Journal Title
JAEA-Conf
Volume: 2021-001
Pages: 138-143
Related Report
Peer Reviewed / Open Access / Int'l Joint Research
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[Journal Article] Change in the Positron Annihilation Lifetime of Vacancy Clusters Containing Hydrogen Atoms in Electron-Irradiated F82H2021
Author(s)
Sato Koichi, Kondo Yohei, Ohta Masakiyo, Xu Qiu, Yabuuchi Atsushi, Kinomura Atsushi, Onoue Masahira, Onitsuka Takash,i Hatakeyama Masahiko, Iwakiri Hirotomo, Kato Daiji, Watanabe Yoshiyuki, Tanigawa Hiroyasu
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Journal Title
Materials Science Forum
Volume: 1024
Pages: 71-78
DOI
Related Report
Peer Reviewed
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[Presentation] Flux pinning engineering by low-energy heavy ion irradiation for GdBa2Cu3Oy coated conductors2021
Author(s)
Toshinori Ozaki, Itsuhiro Kakeya, Tatsunori Okada, Satoshi Awaji, Satoshi Semboshi, Hiroyuki Okazaki, Hiroshi Koshikawa, Shunya Yamamoto, Tetsuya Yamaki, Atsushi Yabuuchi, Tetsuro Sueyoshi, and Hitoshi Sakane
Organizer
virtual 2021 joint 23rd Cryogenic Engineering Conference and International Cryogenic Materials Conference (CEC/ICMC 2021)
Related Report
Int'l Joint Research / Invited
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