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by monolayer hexagonal boron nitride coating for improved photo- and thermionic-cathodesYamaguchi, Hisato*; Yusa, Ryunosuke*; Wang, G.*; Pettes, M. T.*; Liu, F.*; Tsuda, Yasutaka; Yoshigoe, Akitaka; Abukawa, Tadashi*; Moody, N. A.*; Ogawa, Shuichi*
Applied Physics Letters, 122(14), p.141901_1 - 141901_7, 2023/04
Times Cited Count：3 Percentile：81.68(Physics, Applied)A lowering of work function for LaB by monolayer hexagonal BN coating is reported. Photoemission electron microcopy (PEEM) and thermionic emission electron microscopy (TEEM) both revealed that the hBN coated region of a LaB(100) single crystal has lower work function compared to the bare (i.e., non-coated) and graphene coated regions. A larger decrease of work function for the hBN coated LaB(100) compared to graphene coated LaB(100) was qualitatively supported by our density functional theory (DFT) calculations. Adding an oxide layer in the calculations improved consistency between the calculation and experimental results. We followed up our calculations with synchrotron-radiation X-ray photoelectron spectroscopy (SR-XPS) and confirmed the presence of an oxide layer on our LaB.
Yoshida, Kenta*; Toyama, Takeshi*; Inoue, Koji*; Nagai, Yasuyoshi*; Shimodaira, Masaki
Materia, 62(3), p.154 - 158, 2023/03
no abstracts in English
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.
Yoshigoe, Akitaka
Hoshako Riyo No Tebiki, p.130 - 138, 2019/02
The educational book on next-generation synchrotron radiation usage is partially written. This book is being planned by several professors at Tohoku University. In this book, the contents which have already reported in our recent paper [Appl. Phys. Lett. 112 (2018) 021603.] are mainly written. The future perspective on photoemission electron microscopy using next generation synchrotron radiation and its possibility to analyze environmental samples and insulating functional materials are also described.
Yoshigoe, Akitaka; Shiwaku, Hideaki; Kobayashi, Toru; Shimoyama, Iwao; Matsumura, Daiju; Tsuji, Takuya; Nishihata, Yasuo; Kogure, Toshihiro*; Okochi, Takuo*; Yasui, Akira*; et al.
Applied Physics Letters, 112(2), p.021603_1 - 021603_5, 2018/01
Times Cited Count：6 Percentile：29.69(Physics, Applied)A synchrotron radiation photoemission electron microscope (SR-PEEM) was applied to demonstrate pinpoint analysis of micrometer-sized weathered biotite clay particles with artificially adsorbed cesium (Cs) atoms. Despite the insulating properties of the clay, we observed the spatial distributions of constituent elements (Si, Al, Cs, Mg, Fe) without charging issues. We found that Cs atoms were likely to be adsorbed evenly over the entire particle. Spatially-resolved X-ray absorption spectra (XAS) of the Cs M
-edge region showed Cs to be present in a monocation state (Cs
). Further pinpoint XAS measurements were also performed at the Fe L
-edge to determine the chemical valence of the Fe atoms. Our results demonstrate the utility of SR-PEEM as a tool for spatially-resolved chemical analyses of various environmental substances, which is not limited by the poor conductivity of samples.
-martensite as an intermediate phase during the strain-induced transformation of SUS304 stainless steelHatano, Masaharu*; Kubota, Yoshiki*; Shobu, Takahisa; Mori, Shigeo*
Philosophical Magazine Letters, 96(6), p.220 - 227, 2016/06
Times Cited Count：8 Percentile：35.25(Materials Science, Multidisciplinary)We have investigated the formation process of 
'-martensite from the 
-phase induced by external strain using 
synchrotron diffraction experiments, combined with Lorentz transmission electron microscopy (TEM) and high-resolution TEM observations. It is clearly demonstrated that -martensite with hexagonal symmetry appears as an intermediate structure during the plastic deformation of SUS304 stainless steel. In addition to stacking faults and dislocations, interfaces between the twin structures presumably play a key role in the formation of -martensite.
Taguchi, Tomitsugu; Yamamoto, Shunya; Kodama, Katsuaki; Asaoka, Hidehito
Carbon, 95, p.279 - 285, 2015/12
Times Cited Count：11 Percentile：35.36(Chemistry, Physical)Amorphous SiC nanotubes are successfully synthesized by 340 keV Si ions irradiation of polycrystalline SiC nanotubes for the first time. A polycrystalline/amorphous heterostructure SiC nanotube, in which polycrystalline SiC and amorphous SiC coexist in the same nanotube, is also synthesized by ions irradiation with a mask in front of polycrystalline SiC nanotube. According to electron energy loss spectroscopy evaluation, the plasmon energies of SiC nanotube change rapidly at the interface between polycrystalline and amorphous regions. The volume swelling by amorphization evaluated from the differences of plasmon energies is approximately 5.0%. This result reveals that the further relaxed amorphous SiC nanotubes with higher density can be produced. The graphitic shells in carbon layer of C-SiC nanotube gradually bend to the radial direction of nanotube by the ion irradiation. Since the graphite (002) spots in the selected area electron diffraction pattern are clearly observed even after the ion irradiation, the carbon layer in C-SiC nanotube has certain crystallinity. Moreover, the new multi-walled carbon nanotube with the graphitic shells completely parallel to the radial direction of nanotube is also produced inside the amorphous SiC tubular layer in the case of C-SiC nanotube with large caliber.
Sekiguchi, Tetsuhiro; Baba, Yuji; Hirao, Norie; Honda, Mitsunori; Izumi, Toshinori; Ikeura, Hiromi*
Molecular Crystals and Liquid Crystals, 622(1), p.44 - 49, 2015/12
Times Cited Count：0 Percentile：0.01(Chemistry, Multidisciplinary)The molecular orientation is one of the important factors for controlling various properties in organic semiconductor materials. Films are usually heterogeneous. Thus they exist as a mixture of microscopic domains which have a variety of orientation directions. Therefore, it is essential to observe selectively microscopic domains with different orientation direction. In this work, we have developed the photoelectron emission microscopy (PEEM) system combined with the linearly polarized vacuum ultraviolet (VUV) light or synchrotron radiation (SR) X-rays. PEEM images (FOV = ca.50 micro m) for poly(3-hexylthiophene), P3HT thin films were observed under the UV irradiation with various polarization angles, including in-plain and out-of-plain polarization. Morphologies at some bright parts are different each other. The resultant observation suggests that it enables us to distinguish oriented micro-domains with specific directions of polymer chain axis from other amorphous parts.
Terauchi, Masami*; Imazono, Takashi; Koike, Masato
Hyomen Kagaku, 36(4), p.184 - 188, 2015/04
Electron beam induced soft-X-ray emission spectroscopy (SXES) that uses a grating spectrometer has been introduced to a conventional scanning electron microscope (SEM) for characterizing desired specimen areas of bulk materials. The spectrometer has a grazing-incidence flat-field optics by using aberration corrected (varied-line-spacing) gratings, which has already been applied to transmission electron microscopes. The best resolution was confirmed as 0.13 eV at Mg L-emission (50 eV), which is comparable with that of recent dedicated electron energy-loss spectroscopy instruments. Apparent band structure effects have been observed in Mg-L, Si-L, B-K, and Ti-L emission spectra obtained from bulk materials using SEM-SXES instrument.
Mukai, Hiroki*; Hatta, Tamao*; Kitazawa, Hideaki*; Yamada, Hirohisa*; Yaita, Tsuyoshi; Kogure, Toshihiro*
Environmental Science & Technology, 48(22), p.13053 - 13059, 2014/12
Times Cited Count：113 Percentile：94.5(Engineering, Environmental)no abstracts in English
Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Hirao, Norie; Honda, Mitsunori; Izumi, Toshinori; Ikeura, Hiromi*
Photon Factory Activity Report 2013, Part B, P. 546, 2014/00
The molecular orientation is one of the important factors for controlling various properties in organic semiconductor materials. Films are usually heterogeneous. Thus they exist as a mixture of microscopic domains which have a variety of orientation directions. Therefore, it is essential to observe selectively microscopic domains with different orientation direction. In this work, we have developed the photoelectron emission microscope (PEEM) system combined with the linearly polarized vacuum ultraviolet (VUV) light or synchrotron radiation (SR) X-rays. PEEM images for poly(3-hexylthiophene), P3HT thin films were observed under synchrotron X-ray irradiation with linearly polarization. In conclusion, it was found that PEEM with polarized synchrotron can be a powerful tool that gives information of molecular orientation in nano-meter scale.
-TiAl intermetallic compoundsSawai, Tomotsugu; Hishinuma, Akimichi
Journal of Physics and Chemistry of Solids, 66(2-4), p.335 - 338, 2005/02
Times Cited Count：14 Percentile：52.05(Chemistry, Multidisciplinary)TiAl intermetallic compounds are potential materials for high temperature structural applications. They have also low induced radio-activity and good radiation resistance, which make these alloys very attractive in nuclear applications. Their ductility at low temperatures should be, however, still improved and their deformation mechanism is of great concern. In this study, intersections of deformation twins in -TiAl grains were examined in Ti-47at%Al alloy specimens tensile-tested at 873 K. Transmission electron microscopy (TEM) revealed 1/2
110]{111} ordinary-type dislocations and 1/6112]{111} twins in deformed -TiAl grains. Some -TiAl grains contained twins on two different {111} planes, which intersect along 110] directions (type-1). No twin intersection along 101] (type-2) was observed, which was often reported in compressed specimens. Results are discussed with the Schmid factor distributions of twinning systems and ordinary slip systems as the function of tensile directions.
Kasukabe, Yoshitaka*; Wang, J. J.*; Yamamura, Tsutomu*; Yamamoto, Shunya; Fujino, Yutaka*
Thin Solid Films, 464-465, p.180 - 184, 2004/10
Times Cited Count：9 Percentile：43.95(Materials Science, Multidisciplinary)no abstracts in English
Wang, J. J.*; Kasukabe, Yoshitaka*; Yamamura, Tsutomu*; Yamamoto, Shunya; Fujino, Yutaka*
Thin Solid Films, 464-465, p.175 - 179, 2004/10
Times Cited Count：1 Percentile：7.1(Materials Science, Multidisciplinary)no abstracts in English
Igarashi, Shinichi*; Haraguchi, Masaharu*; Aihara, Jun; Saito, Takeru*; Yamaguchi, Kenji; Yamamoto, Hiroyuki; Hojo, Kiichi
Journal of Electron Microscopy, 53(3), p.223 - 228, 2004/08
Times Cited Count：4 Percentile：24.19(Microscopy)no abstracts in English
-FeSi
thin film formation processesYamamoto, Hiroyuki; Yamaguchi, Kenji; Hojo, Kiichi
Thin Solid Films, 461(1), p.99 - 105, 2004/08
Times Cited Count：10 Percentile：46.79(Materials Science, Multidisciplinary)no abstracts in English
Igarashi, Shinichi*; Katsumata, Toshinobu*; Haraguchi, Masaharu*; Saito, Takeru*; Yamaguchi, Kenji; Yamamoto, Hiroyuki; Hojo, Kiichi
Vacuum, 74(3-4), p.619 - 624, 2004/06
Times Cited Count：6 Percentile：27.8(Materials Science, Multidisciplinary)no abstracts in English
TiShibayama, Tamaki*; Nakamichi, Masaru*; Uchida, Munenori*; Kawamura, Hiroshi; Kinoshita, Hiroshi*; Kiyanagi, Yoshiaki*; Takahashi, Heishichiro*; Nomura, Naoyuki*
JAERI-Conf 2004-006, p.216 - 219, 2004/03
no abstracts in English
Terauchi, Masami*; Koike, Masato
Microscopy and Microanalysis, 9(S02), p.894 - 895, 2003/08
We have been developing a high energy-resolution soft-X-ray spectrometer for a transmission electron microscope to obtain the information of the density of states (DOS) of the valence band (occupied states) from identified small specimen areas. We have designed and produced a new grating. The new varied-line-spacing laminar-type holographic grating was designed to have a focal distance of about 50 cm. An energy resolution of about 0.7 eV is expected for X-ray energy of about 1000 eV.
Hojo, Tomohiro; Aihara, Jun; Hojo, Kiichi; Furuno, Shigemi*; Yamamoto, Hiroyuki; Nitani, Noriko; Yamashita, Toshiyuki; Minato, Kazuo; Sakuma, Takaaki*
Journal of Nuclear Materials, 319, p.81 - 86, 2003/06
Times Cited Count：18 Percentile：74.33(Materials Science, Multidisciplinary)no abstracts in English
