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Shimizu, Hirotaka*; Kosugi, Shinya*; Tahara, Yuki*; Yasunaga, Kazufumi*; Kaneta, Yasunori*; Ishikawa, Norito; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*
Nuclear Instruments and Methods in Physics Research B, 286, p.291 - 294, 2012/09
Times Cited Count:27 Percentile:87.4(Instruments & Instrumentation)We have studied the magnetic properties of pure CeO irradiated with swift heavy ions. Experiment a results showed that the ferromagnetism was induced even at room temperature by 200 MeV Xe ion irradiation. The value of saturation magnetization, Ms, systematically changes as a function of ion-fluence. The X-ray diffraction (XRD) spectra show that the lattice constant of CeO increases with increasing ion-fluence. This result and our previous XPS result show that the ion-irradiation produced oxygen vacancies. The present study implies that the ferromagnetic behavior of the ion-irradiated CeO is attributed to the magnetic moments of localized 4f electrons on Ce atoms, which are related to oxygen vacancies.
Tahara, Yuki*; Shimizu, Hirotaka*; Ishikawa, Norito; Okamoto, Yoshihiro; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*
Nuclear Instruments and Methods in Physics Research B, 277, p.53 - 57, 2012/04
In this study, to simulate such an environment, GdO-doped CeO samples were irradiated with 200 MeV Xe ions at room temperature using an ion beam accelerator at JAEA-Tokai. As CeO has the same fluorite structure as that of UO and several properties of CeO are similar to UO, in this study CeO was used as a simulation material of UO. To study the effects of the ion irradiation on GdO-doped CeO, extended X-ray absorption fine structure (EXAFS) and X-ray photoelectron spectroscopy (XPS) were used at the Photon Factory of High Energy Accelerator Research Organization (KEK) as well as conventional X-ray diffraction (XRD) measurement. The EXAFS and XRD spectra show that the effects of the ion irradiation are more pronounced for higher amount of GdO dopant.
Tahara, Yuki*; Shimizu, Hirotaka*; Ishikawa, Norito; Okamoto, Yoshihiro; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*
Nuclear Instruments and Methods in Physics Research B, 277, p.53 - 57, 2012/04
Times Cited Count:11 Percentile:63.23(Instruments & Instrumentation)To study the effects of GdO-doping and the irradiation with high energy fission products in the nuclear fuels (UO), GdO-doped CeO pellets were irradiated with 200 MeV Xe ions. Effects of GdO-doping and the ion irradiation were estimated by using Extended X-ray Absorption Fine Structure (EXAFS) measurement. The interatomic distances between each Ce and the first nearest O atoms, and Ce and the second nearest Ce atoms increase by the irradiation and the effect of the ion irradiation on the atomic distances is more pronounced for higher amounts of dopant. The Debye-Waller factors for Ce-O and Ce-Ce pairs increase with increasing the amount of GdO dopant. These results suggest that the lattice binding energy is weakened by GdO-doping. The Debye-Waller factors increase also by the irradiation. The effect of ion irradiation on the Debye-Waller factors, however, becomes smaller for higher amounts of dopant.
Tahara, Yuki*; Zhu, B.-L.*; Kosugi, Shinya*; Ishikawa, Norito; Okamoto, Yoshihiro; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*
Nuclear Instruments and Methods in Physics Research B, 269(9), p.886 - 889, 2011/05
Times Cited Count:16 Percentile:75.64(Instruments & Instrumentation)CeO pellets doped with GdO were irradiated with 200-MeV Xe ions, and the effects of GdO-doping and irradiation on the lattice structure were measured using XRD and EXAFS. The lattice constant decreases with increasing GdO-doping and the local structure near the Gd atoms is more disordered with increasing amounts of GdO-dopant. The irradiation induces an expansion of the lattice and disordering of the atomic arrangement around Gd atoms. The effect of high-energy ion irradiation becomes more pronounced with increasing amounts of GdO-dopant.
Kosugi, Shinya*; Matsui, Toshiyuki*; Ishikawa, Norito; Ito, Masayoshi*; Sakurai, Yoshiharu*; Aiko, Kazuma*; Shimizu, Hirotaka*; Tahara, Yuki*; Hori, Fuminobu*; Iwase, Akihiro*
Journal of Applied Physics, 109(7), p.07B737_1 - 07B737_3, 2011/04
Times Cited Count:7 Percentile:31.11(Physics, Applied)The magnetic Compton profiles of FeRh intermetallic compound were measured to study the ferromagnetism induced by 200 MeV Xe ion irradiation. The magnetic effect at 50 K increases with increasing the ion-fluence. The analysis of the experimental result revealed that the values of spin moment induced by the irradiation were close to the values of magnetization obtained by a superconducting quantum interference device magnetometer, suggesting that the ion irradiation mainly induces the spin magnetic moment.
Tahara, Yuki*; Zhu, B.-L.*; Kosugi, Shinya*; Ishikawa, Norito; Okamoto, Yoshihiro; Baba, Yuji; Hirao, Norie; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*
no journal, ,
In present light-water nuclear power plants, it is useful to dope some elements, which have a high neutron absorption cross section, into fuels (UO) in order to control the initial reactivity. During the operation of reactors, UO fuels are exposed to irradiation with high energy fission products which have energies around 100 MeV. Therefore, it is important to study the effects of high energy fission products on UO fuels. Cerium dioxide (CeO) has been used so far as a simulation material for UO because it has the same fluorite structure as that of UO. In this study, CeO pellets doped with GdO were irradiated with 200 MeV Xe ions to simulate the irradiation effects of high energy fission products on UO doped with GdO. The X-ray diffraction spectra show that the lattice constant of CeO increases with increasing the amount of the Gd-doping. In addition, it also increases by the irradiation and the effect of the irradiation becomes more remarkable by doping GdO.
Tahara, Yuki*; Zhu, B.-L.*; Kosugi, Shinya*; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*; Ishikawa, Norito; Okamoto, Yoshihiro; Baba, Yuji; Hirao, Norie
no journal, ,
no abstracts in English
Tahara, Yuki*; Zhu, B.-L.*; Kosugi, Shinya*; Hori, Fuminobu*; Matsui, Toshiyuki*; Iwase, Akihiro*; Ishikawa, Norito; Okamoto, Yoshihiro; Baba, Yuji; Hirao, Norie
no journal, ,
no abstracts in English