Structure and magnetic properties of Fe nanoparticles in amorphous silica implanted with Fe ions and effect of subsequent energetic heavy ion irradiation

Iwase, Akihiro*; Fukuda, Kengo*; Saito, Yuichi*; Okamoto, Yoshihiro; Semboshi, Satoshi*; Amekura, Hiroshi*; Matsui, Toshiyuki*

Journal of Applied Physics, 132(16), p.163902_1 - 163902_10, 2022/10

https://doi.org/10.1063/5.0102438

Amorphous SiO samples were implanted with 380 keV Fe ions at room temperature. After implantation, some of the samples were irradiated with 16 MeV Au ions. magnetic properties were investigated using a SQUID magnetometer, and the morphology of the Fe-implanted SiO samples was examined using transmission electron microscopy and X-ray absorption spectroscopy (EXAFS and XANES), which showed that the size of Fe nanoparticles was increasing The size of Fe nanoparticles increased with increasing Fe implantation amount; some of the Fe nanoparticles consisted of Fe oxides, and the valence and structure of Fe atoms became closer to that of metallic -Fe with increasing Fe injection amount. The magnetization-field curve of the sample implanted with a small amount of Fe was reproduced by Langevin's equation, suggesting that the Fe nanoparticles behave in a superparamagnetic manner. In addition, when a large amount of Fe was implanted, the magnetization-magnetic field curve shows a ferromagnetic state. These magnetic property results are consistent with the X-ray absorption results. Subsequent 16 MeV Au irradiation crushed the Fe nanoparticles, resulting in a decrease in magnetization.

Ion species/energy dependence of irradiation-induced lattice structure transformation and surface hardness of NiNb and NiTa intermetallic compounds

Kojima, Hiroshi*; Kaneno, Yasuyuki*; Ochi, Masaaki*; Semboshi, Satoshi*; Hori, Fuminobu*; Saito, Yuichi*; Ishikawa, Norito; Okamoto, Yoshihiro; Iwase, Akihiro*

Materials Transactions, 58(5), p.739 - 748, 2017/05

https://doi.org/10.2320/matertrans.MBW201612

Bulk samples of NiNb and NiTa intermetallic compounds were irradiated with 16 MeV Au, 4.5 MeV Ni, 4.5 MeV Al, 200 MeV Xe and 1.0 MeV He ions, and the change in near-surface lattice structure was investigated by means of the grazing incidence X-ray diffraction (GIXD)and EXAFS. The NiNb and NiTa lattice structures transform from the ordered structures (orthorhombic and monoclinic structures for NiNb and NiTa, respectively) to the amorphous state by the Au, Ni, Al and Xe ion irradiations. Irrespective of such heavy ion species or energies, the lattice structure transformation to the amorphous state almost correlate with the density of energy deposited through elastic collisions.

Radiation enhanced precipitation of solute atoms in AlCu binary alloys; Energetic ion irradiation experiment and computer simulation

Mayumi, Ren*; Semboshi, Satoshi*; Okamoto, Yoshihiro; Saito, Yuichi*; Yoshiie, Toshimasa*; Iwase, Akihiro*

Transactions of the Materials Research Society of Japan, 42(1), p.9 - 14, 2017/02

https://doi.org/10.14723/tmrsj.42.9

AlCu binary alloys were irradiated with 16 MeV Au, 4.5 MeV Ni or 4.5 MeV Al ions at room temperature. Changes in surface hardness and the local atomic structure around Cu atoms were examined by using the Vickers hardness measurement and the EXAFS measurements, respectively. Some specimens were aged at 453 K and Vickers hardness was measured. The computer simulation was also performed by using the rate equation method. The hardness of irradiated specimens increased much faster than that of the aged specimens and it became larger than the maximum value of the hardness for the aged specimens. The comparison of the experimental EXAFS result with that of FEFF simulation suggests that the ion irradiation produced small Cu precipitates in the specimens. The computer simulation visualized the growth process of Cu precipitates during the irradiation, and the result qualitatively corresponds to the experimental result.

Nitrogen K-edge X-ray absorption near edge structure of pyrimidine-containing nucleotides in aqueous solution

Shimada, Hiroyuki*; Minami, Hirotake*; Okuizumi, Naoto*; Sakuma, Ichiro*; Ukai, Masatoshi*; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro*; Saito, Yuji

Journal of Chemical Physics, 142(17), p.175102_1 - 175102_9, 2015/05

AA2015-0073.pdf:1.15MB

https://doi.org/10.1063/1.4919744

Mathematical Modeling of Radioactive Contaminants in the Fukushima Environment

Kitamura, Akihiro; Kurikami, Hiroshi; Yamaguchi, Masaaki; Oda, Yoshihiro; Saito, Tatsuo; Kato, Tomoko; Niizato, Tadafumi; Iijima, Kazuki; Sato, Haruo; Yui, Mikazu; et al.

Nuclear Science and Engineering, 179(1), p.104 - 118, 2015/01

https://doi.org/10.13182/NSE13-89

The prediction of the distribution and fate of radioactive materials eventually deposited at surface in the Fukushima area is one of the main objectives and expected to be achieved in an efficient manner. In order to make such prediction, a number of mathematical models of radioactive contaminants, with particular attention on cesium, on the land and in rivers, lakes, and estuaries in the Fukushima area are developed. Simulation results are examined with the field investigations simultaneously implemented. The basic studies of the adsorption/absorption mechanism of cesium and soils have been performed to shed light on estimating distribution coefficient between dissolved contaminant and particulate contaminant.

Structural changes of nucleic acid base in aqueous solution as observed in X-ray absorption near edge structure (XANES)

Shimada, Hiroyuki*; Fukao, Taishi*; Minami, Hirotake*; Ukai, Masatoshi*; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro*; Saito, Yuji

Chemical Physics Letters, 591, p.137 - 141, 2014/01

https://doi.org/10.1016/j.cplett.2013.11.026

Inspection and repair techniques in the reactor vessel of the experimental fast reactor Joyo; Observation technical development in a reactor vessel of the fast reactor

Imaizumi, Kazuyuki; Saito, Takakazu; Tobita, Shigeharu; Nagai, Akinori; Kitamura, Ryoichi; Okazaki, Yoshihiro

JAEA-Technology 2012-027, 49 Pages, 2012/08

JAEA-Technology-2012-027.pdf:7.07MB

In-Vessel Observations (IVO) techniques for Sodium cooled Fast Reactors (SFRs) are important in confirming its safety and integrity. In order to secure the reliability of IVO techniques, it was necessary to demonstrate the performance under the actual reactor environment with high temperature, high radiation dose and remained sodium. During the investigation of an incident occurred in Joyo, the following observation systems were specifically developed for Joyo. And the following two observations were conducted. (1) Simple overhead observation using a standard video camera for the top of the sub-assemblies and the in-vessel storage rack (2) Narrow space observation using remote handling device equipped with radiation-resistant fiberscope for the bottom face of the upper core structure. As a result, the observations under the actual reactor environment were successfully made even in the narrow space in the reactor vessel and the results provided useful information on incident investigations and planning of restoration work.

Development of manufacturing technologies for ITER Toroidal Field coil conductors

Hamada, Kazuya; Takahashi, Yoshikazu; Nabara, Yoshihiro; Kawano, Katsumi; Ebisawa, Noboru; Oshikiri, Masayuki; Tsutsumi, Fumiaki; Saito, Toru*; Nakajima, Hideo; Matsuda, Hidemitsu*; et al.

Teion Kogaku, 47(3), p.153 - 159, 2012/03

https://doi.org/10.2221/jcsj.47.153

The Japan Atomic Energy Agency (JAEA) has the responsibility to procure 25% of the ITER Toroidal Field coil conductors as the Japanese Domestic Agency (JADA) in the ITER project. The TF conductor is a circular shaped, cable-in-conduit conductor, composed of a cable and a stainless steel conduit (jacket). The outer diameter and maximum length of the TF conductor are 43.7 mm and 760 m, respectively. JAEA has constructed newly conductor manufacturing facility. Prior to starting conductor, JAEA manufactured a 760-m long Cu dummy conductor as process qualification of dummy cable, the jacket sections and fabrication procedures, such as welding, cable insertion, compaction and spooling. Following qualification of all manufacturing processes, JAEA has started to fabricate superconducting conductors for the TF coils.

Effects of energetic heavy ion irradiation on the structure and magnetic properties of FeRh thin films

Fujita, Naoki*; Kosugi, Shinya*; Zushi, Yoshihiro*; Matsui, Toshiyuki*; Saito, Yuichi; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 267(6), p.921 - 924, 2009/04

https://doi.org/10.1016/j.nimb.2009.02.054

The H-Invitational Database (H-InvDB); A Comprehensive annotation resource for human genes and transcripts

Yamasaki, Chisato*; Murakami, Katsuhiko*; Fujii, Yasuyuki*; Sato, Yoshiharu*; Harada, Erimi*; Takeda, Junichi*; Taniya, Takayuki*; Sakate, Ryuichi*; Kikugawa, Shingo*; Shimada, Makoto*; et al.

Nucleic Acids Research, 36(Database), p.D793 - D799, 2008/01

https://doi.org/10.1093/nar/gkm999

Here we report the new features and improvements in our latest release of the H-Invitational Database, a comprehensive annotation resource for human genes and transcripts. H-InvDB, originally developed as an integrated database of the human transcriptome based on extensive annotation of large sets of fulllength cDNA (FLcDNA) clones, now provides annotation for 120 558 human mRNAs extracted from the International Nucleotide Sequence Databases (INSD), in addition to 54 978 human FLcDNAs, in the latest release H-InvDB. We mapped those human transcripts onto the human genome sequences (NCBI build 36.1) and determined 34 699 human gene clusters, which could define 34 057 protein-coding and 642 non-protein-coding loci; 858 transcribed loci overlapped with predicted pseudogenes.