| 研究実績の概要 |
Fluorite ceramic oxides are radiation resistance materials and Gd2O3 doped CeO2 (GDC) is considerable as a surrogate of nuclear fuels such as (U,Gd)O2. The oxygen vacancies (VOs) are created in GDC for charge compensation and excitation which lead the synergetic effect for radiation damage recovery. GDC with different Gd concentrations were irradiated by heavy ions in high ion fluences. Virgin and irradiated samples were measured in long- and medium-range scales to evaluate disordering induced by irradiation or intrinsic VOs induced by Gd ions doping. In addition, images of damaged regions were evaluated by using TEM. In-situ cathodoluminescence spectra for virgin samples under high energy electron irradiation were compared to ceria to investigate charge states of VOs in-beam condition.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
Most of the research proceeded as it planned. Since GDC samples were prepared at constant conditions, they could be measured before ion irradiation in proper. Moreover, taking images using TEM was not previously planned, but it was added to supplement the validity of research data.
However, due to covid-19 in 2021, business trips were not possible, so the ion irradiation experiment conducted by JAEA was delayed or canceled thereby the irradiation study was delayed. In addition, in-situ Raman spectroscopy experiment at CEA in France could not be conducted myself because studying abroad was impossible due to the covid-19.
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| 今後の研究の推進方策 |
Intrinsic oxygen vacancy (Vo) creation in GDC is mostly fixed by Gd3+ dopant for charge compensation. Microstructure changes have to be interpreted in virgin GDC induced by the Vo creation in the lattice by diffracted patterns and Raman spectroscopy. In addition, GDC samples are irradiated by heavy ion (200 MeV) in not only high but also low ion fluences. Damaged GDC samples produce lattice disordering and ion tracks thereby damaged regions and phase transitions depending on Gd contents and fluences are examined by XRD and TEM. Also, charge states of oxygen point defects in damaged samples are measured under high energy electron irradiation by using HVEM. Finally, we propose the synergetic effects and F center and electronic configurations in GDC samples.
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