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-decaying millisecond isomeric state in 
Cd
Jungclaus, A.*; Grawe, H.*; Nishimura, Shunji*; Doornenbal, P.*; Lorusso, G.*; Simpson, G. S.*; S
derstrm, P.-A.*; Sumikama, Toshiyuki*; Taprogge, J.*; Xu, Z. Y.*; et al.
Physics Letters B, 772, p.483 - 488, 2017/09
Times Cited Count：8 Percentile：55.37(Astronomy & Astrophysics)
decay of semi-magic 
Cd; Revision and extension of the level scheme of InJungclaus, A.*; Grawe, H.*; Nishimura, Shunji*; Doornenbal, P.*; Lorusso, G.*; Simpson, G. S.*; Sderstrm, P. A.*; Sumikama, Toshiyuki*; Taprogge, J.*; Xu, Z. Y.*; et al.
Physical Review C, 94(2), p.024303_1 - 024303_8, 2016/08
Times Cited Count：18 Percentile：77.39(Physics, Nuclear) rays emitted from excited states south-east of 
Sn; The 
g
multiplet of In
Jungclaus, A.*; Gargano, A.*; Grawe, H.*; Taprogge, J.*; Nishimura, Shunji*; Doornenbal, P.*; Lorusso, G.*; Shimizu, Y.*; Simpson, G. S.*; Sderstrm, P.-A.*; et al.
Physical Review C, 93(4), p.041301_1 - 041301_6, 2016/04
Times Cited Count：18 Percentile：77.39(Physics, Nuclear)Kameda, Jun*; Shimizu, Mayuko
Nendo Kagaku, 54(3), p.105 - 113, 2016/00
decay of 
Cd and excited states in InTaprogge, J.*; Jungclaus, A.*; Grawe, H.*; Nishimura, Shunji*; Doornenbal, P.*; Lorusso, G.*; Simpson, G. S.*; Sderstrm, P.-A.*; Sumikama, Toshiyuki*; Xu, Z. Y.*; et al.
Physical Review C, 91(5), p.054324_1 - 054324_11, 2015/05
Times Cited Count：24 Percentile：82.61(Physics, Nuclear)-decay half-lives of 110 neutron-rich nuclei across the 
=82 shell gap; Implications for the mechanism and universality of the astrophysical 
processLorusso, G.*; Nishimura, Shunji*; Xu, Z. Y.*; Jungclaus, A.*; Shimizu, Y.*; Simpson, G. S.*; Sderstrm, P.-A.*; Watanabe, H.*; Browne, F.*; Doornenbal, P.*; et al.
Physical Review Letters, 114(19), p.192501_1 - 192501_7, 2015/05
Times Cited Count：164 Percentile：97.96(Physics, Multidisciplinary)Cd
via the detection of internal conversion and Compton electronsTaprogge, J.*; Jungclaus, A.*; Grawe, H.*; Nishimura, Shunji*; Xu, Z. Y.*; Doornenbal, P.*; Lorusso, G.*; N
cher, E.*; Simpson, G. S.*; Sderstrm, P.-A.*; et al.
Physics Letters B, 738, p.223 - 227, 2014/11
Times Cited Count：23 Percentile：80.23(Astronomy & Astrophysics)
seniority isomers of 
SnSimpson, G. S.*; Gey, G.*; Jungclaus, A.*; Taprogge, J.*; Nishimura, Shunji*; Sieja, K.*; Doornenbal, P.*; Lorusso, G.*; Sderstrm, P.-A.*; Sumikama, Toshiyuki*; et al.
Physical Review Letters, 113(13), p.132502_1 - 132502_6, 2014/09
Times Cited Count：68 Percentile：91.93(Physics, Multidisciplinary)Sn explored with the long-lived isomer in 
PdWatanabe, H.*; Lorusso, G.*; Nishimura, Shunji*; Otsuka, T.*; Ogawa, K.*; Xu, Z. Y.*; Sumikama, Toshiyuki*; Sderstrm, P.-A.*; Doornenbal, P.*; Li, Z.*; et al.
Physical Review Letters, 113(4), p.042502_1 - 042502_6, 2014/07
Times Cited Count：24 Percentile：76.91(Physics, Multidisciplinary)Yamaguchi, Masatake; Kameda, Jun*
Philosophical Magazine, 94(19), p.2131 - 2149, 2014/04
Times Cited Count：17 Percentile：62.1(Materials Science, Multidisciplinary)A significant loss of fracture toughness (
) is induced by intergranular (grain boundary; GB) segregation of metalloid solute in alloy steels. Yet, the mechanism has not been clarified from a multiscale point of view. From a thermodynamic approach aided by first-principles calculations, we show here that segregated solute with higher energetic stability on fracture surfaces causes a larger linear reduction in the ideal work to intergranular fracture (
); i.e., the energy difference between a GB and its two fracture surfaces. Remarkably, the combined analysis with first-principles calculations and fracture mechanics experiments found several orders of magnitude more energy loss in for a specific range in the within only a few tenths of J/m
. These results illustrate that the GB of steel has the threshold energy of atomic cohesion under which catastrophic failure occurs.
proton-hole state in Sn and the shell structure along =82Taprogge, J.*; Jungclaus, A.*; Grawe, H.*; Nishimura, Shunji*; Doornenbal, P.*; Lorusso, G.*; Simpson, G.*; Sderstrm, P.-A.*; Sumikama, Toshiyuki*; Xu, Z. Y.*; et al.
Physical Review Letters, 112(13), p.132501_1 - 132501_6, 2014/04
Times Cited Count：51 Percentile：88.81(Physics, Multidisciplinary)Yamaguchi, Masatake; Kameda, Jun*
Proceedings of 2012 International Hydrogen Conference; Hydrogen-Materials Interactions, p.747 - 755, 2014/01
Atomistic mechanisms of grain boundary (GB) decohesion of iron by solute (P, Sn, Sb, H) segregation are investigated from first-principles calculations. The calculated GB cohesive energy, which is the energy difference between two fracture surfaces and GB, is shown to decrease with increasing the segregation coverage of P, Sn, Sb, H. Furthermore, Hydrogen-induced GB decohesion is shown to be enhanced by the mobility of hydrogen during crack propagation.
Yamaguchi, Masatake; Kameda, Jun*
Dai-57-Kai Nihon Gakujutsu Kaigi Zairyo Kogaku Rengo Koenkai Koen Rombunshu, p.35 - 36, 2013/11
no abstracts in English
Yamaguchi, Masatake; Kameda, Jun*; Ebihara, Kenichi; Itakura, Mitsuhiro; Kaburaki, Hideo
Philosophical Magazine, 92(11), p.1349 - 1368, 2012/04
Times Cited Count：53 Percentile：90.47(Materials Science, Multidisciplinary)Atomistic mechanisms of hydrogen-induced cracking along a bcc Fe 
symmetrical tilt grain boundary (GB) have been studied by first-principles calculations. The mobile and immobile effects of hydrogen on the GB decohesion are analyzed by calculating the dependence of hydrogen segregation energy on the coverage relevant to the repulsive interaction among segregated hydrogen atoms at the GB and on its fracture surfaces, together with generalizing McLean's formula. It was found that the segregation of combined mobile and immobile hydrogen atoms from the bulk and/or GB on the fracture surfaces causes much stronger reduction (70-80%) in the GB cohesive energy. It can occur even at a very low bulk hydrogen content of about 10
atomic fraction during slow cracking. This is in contrast with only 10-20% decohesion induced by immobile hydrogen at much higher hydrogen content during fast cracking.
Takeuchi, Tomoaki; Kameda, Jun*; Nagai, Yasuyoshi*; Toyama, Takeshi*; Nishiyama, Yutaka; Onizawa, Kunio
Journal of Nuclear Materials, 415(2), p.198 - 204, 2011/08
Times Cited Count：35 Percentile：92.33(Materials Science, Multidisciplinary)Microstructural changes by thermal aging in stainless steel weld overlay cladding of nuclear reactor pressure vessels were investigated using atom probe tomography. The cladding material was composed of about 90% austenite phase and 10% 
-ferrite phase and thermally aged at 400
C for 10,000 h. In the ferrite phase, the thermal aging increased a fluctuation of Cr concentration due to spinodal decomposition and caused the precipitation of G phase with chemical composition of Ni:Si:Mn = 16:7:6. Moreover, significant hardening of the ferrite phase was induced by the thermal aging. On the other hand, the thermal aging did not affect on the microstructures and the hardness in the austenite phase, which indicates the microstructural changes were responsible for the hardening in the ferrite phase. The analyses of the magnitude of the spinodal decomposition and the hardness implied that the spinodal decomposition was the main cause of the hardening.
Takeuchi, Tomoaki; Kuramoto, Akira*; Kameda, Jun*; Toyama, Takeshi*; Nagai, Yasuyoshi*; Hasegawa, Masayuki*; Okubo, Tadakatsu*; Yoshiie, Toshimasa*; Nishiyama, Yutaka; Onizawa, Kunio
Journal of Nuclear Materials, 402(2-3), p.93 - 101, 2010/07
Times Cited Count：59 Percentile：96.23(Materials Science, Multidisciplinary)This study reports the effects of the composition and dose on microstructure evolution and hardening in high- and low-impurity A533B-1 steels neutron-irradiated in a wide range from 0.32 to 9.9 
10
n cm
(E 
1 MeV) under a constant high flux at JMTR. The early hardening was found to be caused by mainly matrix defects. The gradual hardening after middle stage of irradiation was found to be caused by the formation of Cu rich clusters (CRCs) and Mn-Ni-Si rich clusters (MNSCs), respectively, in the high- and low-impurity steels. By applying a RB model, it was found that the dislocation-pinning strength of the CRCs and MNSCs is almost the same. Moreover, the high-impurity steel subjected to the highest dose revealed the formation of MNSCs.
Nishiyama, Yutaka; Onizawa, Kunio; Suzuki, Masahide; Anderegg, J. W.*; Nagai, Yasuyoshi*; Toyama, Takeshi*; Hasegawa, Masayuki*; Kameda, Jun*
Acta Materialia, 56(16), p.4510 - 4521, 2008/09
Times Cited Count：67 Percentile：92.13(Materials Science, Multidisciplinary)The effects of intergranular P segregation and hardening on the ductile-to-brittle transition temperature (DBTT) in several neutron-irradiated reactor pressure vessel steels with different bulk contents of P and Cu have been investigated using a scanning Auger microbe, a local electrode atom probe and positron annihilation spectroscopy. Increasing the neutron fluence at 563 K promotes intergranular P segregation. The content of P more significantly affects irradiation hardening than that of Cu due to distinct formation of P-rich precipitates arising from the stabilization of vacancies. Analyzing the correlations between the P segregation, hardening, fraction of intergranular fracture and DBTT, it is found neutron irradiation mitigates an embrittling effect of segregated P, and therefore the hardening more strongly affects the DBTT shift than the P segregation.
Nishiyama, Yutaka; Liu, X.*; Kameda, Jun*
Metallurgical and Materials Transactions A, 39(5), p.1118 - 1131, 2008/05
Times Cited Count：2 Percentile：20.62(Materials Science, Multidisciplinary)Tanaka, Satoru*; Nagasaki, Shinya*; Nakata, Kotaro*; Oda, Takuji*; Kameda, Jun*; Kamei, Gento; Tachi, Yukio
JNC TY8400 2003-008, 88 Pages, 2003/05
JNC-TY8400-2003-008.pdf:1.29MB
Redox reactions between Cr(VI) and iron(II) chloride (FeCl2) and those between Cr(VI) and magnetite (Fe(II)1Fe(III)2O4) were observed as a preliminary study. According to the experimental results, it was suggested that the redox reactions were promoted more than the amount of Fe(II) on magnetite surface because of electron transfer from internal Fe(II) to magnetite surface. The results were quantitatively supported from quantum chemical calculations. Redox reactions between Np(V) and magnetite and the reduction of Np to tetravalent were observed, while those between Np(V) and FeCl2 were not observed obviously. It was observed that the reactions were promoted rapidly when the magnetite / solution ratio and the temperature were high, and the rate constant of the reactions was obtained. Furthermore, it was found that hydrogen gas and hydrogen ion were generated with crushing the quartz in an inert gas atmosphere.
Kameda, Jun*; Nishiyama, Yutaka; Bloomer, T. E.*
Surface and Interface Analysis, 31(7), p.522 - 531, 2001/07
Times Cited Count：10 Percentile：28.89(Chemistry, Physical)This study describes intergranular segregation and embrittlement in several model ferritic alloys doped with Mn, P, S and/or Cu subjected to neutron irradiation, irradiation-equivalent thermal ageing (ETA) and post-irradiation annealing (PIA). Neutron irradiation produced a larger amount of intergranular P segregation than S segregation. Intergranular C segregation remained small in all the as-irradiated alloys. A PIA study has shown that the P segregation in P-doped alloys subjected to lower temperature PIA proceeds via mobile P-interstitial complexes while the S segregation is controlled by vacancy-enhanced diffusion. The mechanisms of non-equilibrium intergranular segregation induced by neutron irradiation are discussed in light of coupled fluxes of point defects and impurities, and changes in the segregation capacity of grain boundaries. Small punch tests demonstrated how the impurity segregation or desegregation and hardening or softening induced by the irradiation, ETA and PIA influence intergranular embrittlement in the various ferritic alloys.
