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Sn
S
-based shandite filmsLau, Y.-C.*; Ikeda, Junya*; Fujiwara, Kohei*; Ozawa, Akihiro*; Zheng, J.*; Seki, Takeshi*; Nomura, Kentaro*; Du, L.*; Wu, Q.*; Tsukazaki, Atsushi*; et al.
Physical Review B, 108(6), p.064429_1 - 064429_11, 2023/08
Times Cited Count:15 Percentile:72.09(Materials Science, Multidisciplinary)
WB-STEM observation of dislocation loop behavior in reactor pressure vessel steel during post-irradiation annealingDu, Y.*; Yoshida, Kenta*; Shimada, Yusuke*; Toyama, Takeshi*; Inoue, Koji*; Arakawa, Kazuto*; Suzudo, Tomoaki; Milan, K. J.*; Gerard, R.*; Onuki, Somei*; et al.
Materialia, 12, p.100778_1 - 100778_10, 2020/08
In order to ensure the integrity of the reactor pressure vessel in the long term, it is necessary to understand the effects of irradiation on the materials. In this study, irradiation-induced dislocation loops were observed in neutron-irradiated reactor pressure vessel specimens during annealing using our newly developed WB-STEM. It was confirmed that the proportion of
loops increased with increasing annealing temperature. We also succeeded in observing the phenomenon that two 
loops collide into a
loop. Moreover, a phenomenon in which dislocation loops decorate dislocations was also observed, and the mechanism was successfully explained by molecular dynamics simulation.
Wang, C.*; Daiwei, Y.*; Liu, X.*; Chen, R.*; Du, X.*; Hu, B.*; Wang, L.*; Iida, Kazuki*; Kamazawa, Kazuya*; Wakimoto, Shuichi; et al.
Physical Review B, 96(8), p.085111_1 - 085111_5, 2017/08
Times Cited Count:12 Percentile:41.85(Materials Science, Multidisciplinary)
Cs
Fe
Se
Hawai, Takafumi*; Nambu, Yusuke*; Ogushi, Kenya*; Du, F.*; Hirata, Yasuyuki*; Avdeev, M.*; Uwatoko, Yoshiya; Sekine, Yurina; Fukazawa, Hiroshi; Ma, J.*; et al.
Physical Review B, 91(18), p.184416_1 - 184416_11, 2015/05
Times Cited Count:19 Percentile:57.04(Materials Science, Multidisciplinary)We investigated the iron-based ladder compounds (Ba, Cs)Fe
Se
, whose parent compounds, BaFe
Se
and CsFe
Se
, have different space groups, formal valences of Fe and magnetic structures. Electrical resistivity, specific heat, magnetic susceptibility, X-ray diffraction and powder neutron diffraction measurements were conducted to obtain the temperature and composition phase diagram of this system. Block magnetism seen in BaFe
Se
is drastically suppressed with Cs doping. In contrast, stripe magnetism observed in CsFe
Se
more resilient to Ba doping. Novel magnetic structure appears in intermediate compositions, which is similar to the stripe magnetism of CsFe
Se
but with different inter-ladder spin configuration. Intermediate compounds show insulating behavior, nevertheless finite T-linear contribution in specific heat was obtained at low temperature.
Yoshida, Kenta*; Du, Y.*; Shimada, Yusuke*; Suzudo, Tomoaki; Toyama, Takeshi*; Inoue, Koji*; Arakawa, Kazuto*; Milan, K. J.*; Gerard, R.*; Nagai, Yasuyoshi*
no journal, ,
We developed a weak-beam scanning transmission electron microscopy (WB-STEM) by installing a novel beam selector, annular detector, a high-speed CCD camera and imaging filter in a camera chamber of an aberration corrected electron microscope. In-situ observation confirmed that the newly-developed WB-STEM has improved the ability to observe the dynamic behavior of dislocation loops. In addition, we performed a numerical simulation of dislocation loop behavior using molecular dynamics, and confirmed that the experimental results were well explained by the theoretical analysis. Therefore, this WB-STEM is expected to be useful for understanding the embrittlement mechanism of nuclear materials such as reactor pressure vessel (RPV) steels.