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promoter on Pt electro-catalystFugane, Keisuke*; Mori, Toshiyuki*; Yan, P.*; Masuda, Takuya*; Yamamoto, Shunya; Ye, F.*; Yoshikawa, Hideki*; Auchterlonie, G.*; Drennan, J.*
ACS Applied Materials & Interfaces, 7(4), p.2698 - 2707, 2015/02
Times Cited Count：30 Percentile：67.05(Nanoscience & Nanotechnology)no abstracts in English
Tokuoka, Naochika*; Kobayashi, Mamoru*; Koyama, Takashi*
PNC TJ1636 96-001, 64 Pages, 1996/03
None
U
O
solid solutionHinatsu, Yukio; Fujino, Takeo
Chemical Physics Letters, 172(2), p.131 - 136, 1990/08
Times Cited Count：8 Percentile：37.22(Chemistry, Physical)no abstracts in English
Journal of Nuclear Science and Technology, 13(9), p.492 - 496, 1976/09
Times Cited Count：3no abstracts in English
Anada, Keito*; Oishi, Yuji*; Serizawa, Hiroyuki; Kaji, Yoshiyuki; Muta, Hiroaki*; Kurosaki, Ken*; Yamanaka, Shinsuke*
no journal, ,
Polyhedral cavities which is called image crystal were observed in the Cerium Oxide sample sintered under reducing atmosphere. The facet became clear with decreasing O/M ratio which facilitates the atomic diffusion rate. This result suggests that the atomic diffusion rate of matrix significantly affects the formation of the image crystals.
Serizawa, Hiroyuki
no journal, ,
My investigation on the cavity in ceramics was triggered by the unexpected discovery of a polyhedral cavity in a UO matrix. The SEM image that fixed my eye's was a cavity found in the fracture surface of single crystal UO that was heat treated in helium at 90 MPa, followed by annealing at 1573 K for 1 h. It was clear that the cavity was a negative crystal which was formed by the precipitation of helium during the heat treatment after HIP injection. In a series of experiments, I noticed that the shape of cavity, when we use the helium injection method, the shape can easily be controlled. Our research team named the shape controlled negative crystal an image crystal. At this moment, we found three types of the image crystal formed in UO. We examined another research on the formation of the image crystal in CeO. I confirmed that nanosized image crystal is formed in the matrix.
Nagai, Takayuki; Kobayashi, Hidekazu; Okamoto, Yoshihiro; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*; Seki, Katsumi*
no journal, ,
no abstracts in English
based simulated fuel containing CsI to evaluate the release behavior of Cs and ITakamatsu, Yuki*; Kurosaki, Ken*; Ishii, Hiroto*; Osaka, Masahiko; Nakajima, Kunihisa; Miwa, Shuhei; Di Lemma, F. G.; Oishi, Yuji*; Muta, Hiroaki*; Yamanaka, Shinsuke*
no journal, ,
We performed spark plasma sintering tests of the cerium dioxide (CeO)-based simulated fuel containing cesium iodide (CsI) for the establishment of synthesis technology of simulated fuel containing volatile fission product (FP) such as cesium (Cs) and iodine (I) which is required for the data acquisition on the FP release behavior. We could successfully fabricate the simulated fuel containing CsI, which had homogeneous distribution of CsI compound, by the spark plasma sintering at lower temperature and in shorter time.
Serizawa, Hiroyuki; Kondo, Sosuke*; Hinoki, Tatsuya*
no journal, ,
Pieces of CeO (100) thin film were heat treated at 1273 K for 2h. The films were irradiated with 130-keV He
ions using 400-keV ion implanter of TIARA. The ion doped film was heat treated at 1773 K for 2 h in air. After the heat treatment, the sample for STEM analysis was prepared for STEM analysis by FIB. It was found that many blisters were formed on the surface of the thin film. The blisters are considered to be formed by gas babble accompanied by the precipitation of He beneath the surface. The lid of the blister is blown away since the sample is ceramics. Many gas babbles are formed in the thin film. The size of the gas bubble falls within the range from 30 to 100 nm in diameter. The shape of the gas bubble is truncated octahedron but clearly different from that of void, which mean that the existence of He in the gas bubble effect on the shape of the gas bubble.
-based simulated fuel containing CsITakamatsu, Yuki*; Kurosaki, Ken*; Ishii, Hiroto*; Oishi, Yuji*; Muta, Hiroaki*; Yamanaka, Shinsuke*; Nakajima, Kunihisa; Suzuki, Eriko; Miwa, Shuhei; Osaka, Masahiko
no journal, ,
We performed spark plasma sintering tests of the cerium dioxide (CeO)-based simulated fuel containing cesium iodide (CsI), in order to establish a synthesis technology of simulated fuel including volatile fission product (FP) such as cesium (Cs) and iodine (I) for a study on the FP release behavior. We could successfully fabricated the simulated fuel containing CsI by the spark plasma sintering at lower temperature and in shorter time. It has homogeneous distribution of CsI compound in the sintered pellet.
Watanabe, Masashi; Tanaka, Kosuke; Kato, Masato
no journal, ,
In this study, the shrinkage behavior of CeO, which is widely used in surrogate material of the nuclear fuel, were studied using a thermomechanical analyzer in various oxygen partial pressure, to discuss the sintering mechanisms under the low oxygen potentials. The shrinkage ratios were significantly different between the air atmosphere and the oxygen partial pressure controlled atmosphere. The shrinkage began at lower temperature with increasing P
/P
ratio. The relationship between P/P ratio and shrinkage ratio in the sintering process of PuO is similar to the result of this study. Therefore, it seems that both have the same sintering mechanism.
Doshi, Satoru*; Maeda, Kazuki*; Taira, Yoshitaka*; Watanabe, Shinta*; Hirade, Tetsuya
no journal, ,
It has been reported that oxygen vacancies in cerium oxide (CeO) affect catalytic activity. There is a need for highly sensitive in-situ measurements of the state and concentration of oxygen vacancies during catalytic reactions, and we are considering using the positron annihilation method. This time, we measured samples with different particle sizes to clarify the sites where positrons are trapped. From the lifetime spectrum of a particle size of 2 nm, which has a high intensity of the long-lived component, we first determined the lifetime value of the longest-lived component to be 390.8
1.6 ps. Next, in the lifetime spectrum of a particle size of 60 nm, where the longest lifetime component is the smallest, the longest lifetime component was fixed at 390.8 ps, and the lifetime value of the other positron trap site was determined to be 199.47.4 ps. These values are close to the lifetimes of positrons trapped in surface and neutral oxygen defects in first-principles calculations.
by using gamma-ray induced positron annihilation lifetime measurementDoshi, Satoru*; Maeda, Kazuki*; Taira, Yoshitaka*; Watanabe, Shinta*; Hirade, Tetsuya
no journal, ,
Gamma-ray-induced positron annihilation lifetime measurement (GiPALS), which utilizes the generation of positrons inside a sample by pair generation with gamma rays, has a significantly smaller background component than conventional measurement methods. It can perform measurements in harsh environments such as high temperature and high pressure because there is no positron source inside the sample. It has been reported that the positron annihilation lifetime spectrum of CeO can be fitted with two components. However, in reality, it is thought that there are at least three components: a component of annihilation in the bulk, a component of annihilation trapped in lattice defects, a component of annihilation trapped on the surface. Therefore, in this study, we tried to fit three components and assigned each by changing the particle size. In addition, we theoretically investigated the bulk, defect, and surface components in the positron annihilation lifetime of CeO using first-principles calculations.
