Local structure investigations of accumulated damage in irradiated MgAlO

Yoshioka, Satoru*; Tsuruta, Konosuke*; Yamamoto, Tomokazu*; Yasuda, Kazuhiro*; Matsumura, Sho*; Sugiyama, Takeharu*; Oba, Yojiro; Ishikawa, Norito; Kobayashi, Eiichi*; Okudaira, Koji*

Journal of the American Ceramic Society, 103(8), p.4654 - 4663, 2020/08

https://doi.org/10.1111/jace.17101

X-ray absorption near edge structure (XANES) and small-angle X-ray scattering (SAXS) reveal the damaged structures in MgAlO spinel induced by swift heavy ions. SAXS indicates the formation of ion tracks with cylindrical shape with a diameter of 5 nm. XANES indicates the cationic disordering between tetrahedral and octahedral sites by the irradiation. Quantitative analysis of XANES also reveals that cations preferably occupy the octahedral sites at high fluence.

Neutron scattering and imaging using neutron transmission spectra

Oba, Yojiro

Hamon, 30(2), p.90 - 93, 2020/05

no abstracts in English

Anomalous small-angle X-ray scattering (ASAXS) study of irradiation-induced nanostructure change in Fe-ion beam irradiated oxide dispersion-strengthened (ODS) steel

Kumada, Takayuki; Oba, Yojiro; Motokawa, Ryuhei; Morooka, Satoshi; Tominaga, Aki; Tanida, Hajime; Shobu, Takahisa; Konno, Azusa; Owada, Kenji*; Ono, Naoko*; et al.

Journal of Nuclear Materials, 528, p.151890_1 - 151890_7, 2020/01

https://doi.org/10.1016/j.jnucmat.2019.151890

We have developed an anomalous small-angle X-ray scattering (ASAXS) diffractometer in SPring-8 to investigate irradiation-induced nanostructural change in ion-beam irradiated stainless steel. A thermally-aged MA956 stainless steel sample displays power-law scattering that follows the Porod law at the magnitude of scattering vector, Q, below 0.5 nm and an overlapped shoulder around 0.7 nm. After the ion-beam irradiation, the intensity of the shoulder remained unchanged, whereas that of the power-law scattering nearly doubled. This result indicates that none of the structural parameters of the Cr-rich nanoprecipitates, such as the number density, size, and interface roughness, were changed by the irradiation.

Characterization of BaZrO nanocolumns in Zr-added (Gd,Y)BaCuOx superconductor tape by anomalous small-angle X-ray scattering

Oba, Yojiro; Sasaki, Hirokazu*; Yamazaki, Satoshi*; Nakasaki, Ryusuke*; Onuma, Masato*

Superconductor Science and Technology, 32(5), p.055011_1 - 055011_5, 2019/05

https://doi.org/10.1088/1361-6668/ab0f55

Imaging measurement of neutron attenuation by small-angle neutron scattering using soller collimator

Oba, Yojiro; Shinohara, Takenao; Sato, Hirotaka*; Onodera, Yohei*; Hiroi, Kosuke; Su, Y.; Sugiyama, Masaaki*

Journal of the Physical Society of Japan, 87(9), p.094004_1 - 094004_5, 2018/09

https://doi.org/10.7566/JPSJ.87.094004

no abstracts in English

Magnetic Bragg dip and Bragg edge in neutron transmission spectra of typical spin superstructures

Mamiya, Hiroaki*; Oba, Yojiro; Terada, Noriki*; Watanabe, Norimichi*; Hiroi, Kosuke; Shinohara, Takenao; Oikawa, Kenichi

Scientific Reports (Internet), 7(1), p.15516_1 - 15516_8, 2017/11

https://doi.org/10.1038/s41598-017-15850-3

no abstracts in English

Quantitative analysis of tempering microstructure via synchrotron X-ray diffraction during heating

Morooka, Satoshi; Kanata, Hiroyuki*; Oba, Yojiro*; Sato, Masugu*

Heisei-28-Nendo SPring-8 Sangyo Shinbunya Shien Kadai, Ippan Kadai (Sangyo Bunya) Jisshi Hokokusho, p.95 - 98, 2017/00

no abstracts in English

Novel neutron scattering techniques using neutron transmission spectra

Oba, Yojiro*; Morooka, Satoshi; Sato, Hirotaka*; Sato, Nobuhiro*; Inoue, Rintaro*; Sugiyama, Masaaki*

Hamon, 26(4), p.170 - 173, 2016/11

Prospect for application of compact accelerator-based neutron source to neutron engineering diffraction

Ikeda, Yoshimasa*; Taketani, Atsushi*; Takamura, Masato*; Sunaga, Hideyuki*; Kumagai, Masayoshi*; Oba, Yojiro*; Otake, Yoshie*; Suzuki, Hiroshi

Nuclear Instruments and Methods in Physics Research A, 833, p.61 - 67, 2016/10

https://doi.org/10.1016/j.nima.2016.06.127

A compact accelerator-based neutron source has been lately discussed on engineering applications such as transmission imaging and small angle scattering as well as reflectometry. However, nobody considers using it for neutron diffraction experiment because of its low neutron flux. In this study, therefore, the neutron diffraction experiments are carried out using Riken Accelerator-driven Compact Neutron Source (RANS), to clarify the capability of the compact neutron source for neutron engineering diffraction. The diffraction pattern from a ferritic steel was successfully measured by suitable arrangement of the optical system to reduce the background noise, and it was confirmed that the recognizable diffraction pattern can be measured by the large sampling volume with 10 mm in cubic for an acceptable measurement time, i.e. 10 minutes. The minimum resolution of the 110 reflection for RANS is approximately 2.5 % at 8 s of the proton pulse width, which is insufficient to perform the strain measurement by neutron diffraction. The moderation time width at the wavelength corresponding to the 110 reflection is estimated to be approximately 30 s, which is the most dominant factor to determine the resolution. Therefore, refinements of the moderator system to decrease the moderation time are important to improve the resolution of the diffraction experiment using the compact neutron source. In contrast, the texture evolution due to plastic deformation was successfully observed by measuring a change in the diffraction peak intensity by RANS. Furthermore, the volume fraction of the austenite phase was also successfully evaluated by fitting the diffraction pattern using a Rietveld code. Consequently, RANS was proved to be capable for neutron engineering diffraction aiming for the easy access measurement of the texture and the amount of retained austenite.

Hierarchical structure-property relationships in graft-type fluorinated polymer electrolyte membranes using small- and ultrasmall-angle X-ray scattering analysis

Tran Duy, T.*; Sawada, Shinichi; Hasegawa, Shin; Yoshimura, Kimio; Oba, Yojiro*; Onuma, Masato*; Katsumura, Yosuke*; Maekawa, Yasunari

Macromolecules, 47(7), p.2373 - 2383, 2014/04

https://doi.org/10.1021/ma500111x

The hierarchical structures of graft-type ETFE-based polymer electrolyte membranes (ETFE-PEMs) were investigated using small- and ultrasmall-angle X-ray cattering experiments. The ETFE-PEMs with IECs 2.4 mmol/g possessed conducting graft domains around lamellar crystals, with a d-spacing of 21.8-29.1 nm, and oriented crystallites with short and long correlation distances of 218-320 and 903-1124 nm, respectively. The membranes with IECs 2.7 mmol/g showed a new phase of crystallite network domains with a d-range of 225-256 nm, indicating a phase transition from oriented crystallite to crystallite network structures in the IEC range of 2.4-2.7 mmol/g. Noted that for the ETFE-PEMs with high IECs higher conductivity at 30% RH and compatible tensile strengths at 100% RH and 80 C, compared with Nafion, originated from the well-interconnected ion channels around the crystallites and the remaining lamellar crystals and crystallites, respectively.