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JAEA Reports

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018) (Translated document)

Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.

JAEA-Research 2020-007, 249 Pages, 2020/10

JAEA-Research-2020-007.pdf:15.83MB

The accident of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, Japan Atomic Energy Agency (JAEA) has been conducting "Long-term Assessment of Transport of Radioactive Contaminants in the Environment of Fukushima" concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.

Journal Articles

High-temperature short-range order in Mn$$_3$$RhSi

Yamauchi, Hiroki; Sari, D. P.*; Watanabe, Isao*; Yasui, Yukio*; Chang, L.-J.*; Kondo, Keietsu; Ito, Takashi; Ishikado, Motoyuki*; Hagiwara, Masato*; Frontzek, M. D.*; et al.

Communications Materials (Internet), 1, p.43_1 - 43_6, 2020/07

High-temperature short-range order is discovered up to 720 K in Mn$$_3$$RhSi by complementary use of neutron scattering and muon spin relaxation measurements.

JAEA Reports

Status of study of long-term assessment of transport of radioactive contaminants in the environment of Fukushima (FY2018)

Nagao, Fumiya; Niizato, Tadafumi; Sasaki, Yoshito; Ito, Satomi; Watanabe, Takayoshi; Dohi, Terumi; Nakanishi, Takahiro; Sakuma, Kazuyuki; Hagiwara, Hiroki; Funaki, Hironori; et al.

JAEA-Research 2019-002, 235 Pages, 2019/08

JAEA-Research-2019-002.pdf:21.04MB

The accident of the Fukushima Daiichi Nuclear Power Station (hereinafter referred to 1F), Tokyo Electric Power Company Holdings, Inc. occurred due to the Great East Japan Earthquake, Sanriku offshore earthquake, of 9.0 magnitude and the accompanying tsunami. As a result, large amount of radioactive materials was released into the environment. Under these circumstances, JAEA has been conducting Long-term Environmental Dynamics Research concerning radioactive materials released in environment, especially migration behavior of radioactive cesium since November 2012. This report is a summary of the research results that have been obtained in environmental dynamics research conducted by JAEA in Fukushima Prefecture.

Journal Articles

Presence of $$varepsilon$$-martensite as an intermediate phase during the strain-induced transformation of SUS304 stainless steel

Hatano, Masaharu*; Kubota, Yoshiki*; Shobu, Takahisa; Mori, Shigeo*

Philosophical Magazine Letters, 96(6), p.220 - 227, 2016/06

 Times Cited Count:6 Percentile:50.42(Materials Science, Multidisciplinary)

We have investigated the formation process of $$alpha$$'-martensite from the $$gamma$$-phase induced by external strain using in-situ synchrotron diffraction experiments, combined with Lorentz transmission electron microscopy (TEM) and high-resolution TEM observations. It is clearly demonstrated that $$varepsilon$$-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 $$varepsilon$$-martensite.

JAEA Reports

Measurement of hydrogen generating from radiolysis of highly active liquid waste and its quantitative evaluation

Yamamoto, Masahiko; Surugaya, Naoki; Mori, Eito; Taguchi, Shigeo; Sato, Soichi

JAEA-Research 2015-013, 27 Pages, 2015/10

JAEA-Research-2015-013.pdf:2.84MB

The H$$_{2}$$ concentration generating from Highly Active Liquid Waste (HALW) of Tokai Reprocessing Plant is measured in a closed experimental system. The experimental results show that H$$_{2}$$ concentration gradually increases at first and then approaches a steady-state due to the H$$_{2}$$ consumption reaction by Pd ions. The highest H$$_{2}$$ concentration is 1200 ppm (0.1%) when the solution temperature is at 23$$^{circ}$$C. It is found that H$$_{2}$$ generating from HALW is equilibrated one order of magnitude lower than the H$$_{2}$$ combustion lower limit. Moreover, a model based on H$$_{2}$$ generation from HALW by the radiolysis and H$$_{2}$$ consumption reaction by Pd ions is proposed and applied to evaluate H$$_{2}$$ concentration behavior in the gas phase. The calculated H$$_{2}$$ concentrations from proposed model agreed well with the experimental values. It is demonstrated that the behavior of H$$_{2}$$ generating from HALW can be evaluated quantitatively by applying the proposed model in this study.

Journal Articles

The Cause of corrosion occurred in a glove box filter casing and its repair technique

Mori, Eito; Yamamoto, Masahiko; Taguchi, Shigeo; Sato, Soichi; Kitao, Takahiko; Surugaya, Naoki

Nippon Hozen Gakkai Dai-11-Kai Gakujutsu Koenkai Yoshishu, p.132 - 138, 2014/07

The contamination of the radioactive material was observed on the filter casing surface of the glove box installed at the analytical laboratory in Tokai Reprocessing Plant. The cause of the contamination was investigated with visual inspection, penetrant testing and ultrasonic thickness measurement. It was found that a micro through-hole due to the corrosion of stainless-steel was generated in the glove box filter casing. The repair work of the filter casing was performed keeping the glove box negative pressure. The corrosion part of filter casing was replaced and newly fabricated casing was connected to the glove box with Tungsten Inert Gas welding method.

Journal Articles

Current-induced enhancement of magnetic anisotropy in spin-charge-coupled multiferroic YbFe$$_{2}$$O$$_{4}$$

Yoshii, Kenji; Matsumura, Daiju; Saito, Hiroyuki; Kambe, Takashi*; Fukunaga, Mamoru*; Muraoka, Yuji*; Ikeda, Naoshi*; Mori, Shigeo*

Journal of the Physical Society of Japan, 83(6), p.063708_1 - 063708_4, 2014/06

 Times Cited Count:4 Percentile:58.33(Physics, Multidisciplinary)

We report the change of magnetic properties of multiferroic YbFe$$_{2}$$O$$_{4}$$, caused by cooling in the presence of an electrical current. The magnetization measured after the cooling becomes smaller by about 10-20% than that after cooling without a current. The current also affects the magnetic anisotropy below about 100 K; the magnetic coercivity is increased by about 10-20%. These phenomena may arise from a coexistence of ferromagnetic and antiferromagnetic domains, or a disturbance in the formation of charge-ordered domains. From the applied viewpoint, the enhancement of anisotropy by an electrical current offers a method for stabilizing magnetization other than the well-known method, i.e., exchange bias.

Journal Articles

Magnetic properties of R$$_{2}$$Fe$$_{3}$$O$$_{7}$$ (R=Yb and Lu)

Yoshii, Kenji; Ikeda, Naoshi*; Fukuyama, Ryota*; Nagata, Tomoko*; Kambe, Takashi*; Yoneda, Yasuhiro; Fukuda, Tatsuo; Mori, Shigeo*

Solid State Communications, 173, p.34 - 37, 2013/11

 Times Cited Count:1 Percentile:93.46(Physics, Condensed Matter)

We have investigated the magnetic properties of R$$_{2}$$Fe$$_{3}$$O$$_{7}$$ (R=Yb and Lu), which belongs to the homologous family of electronic ferroelectric RFe$$_{2}$$O$$_{4}$$. Magnetization measurements show ferrimagnetic ordering at the Neel temperature (T$$_{N}$$) of about 270 K, which is slightly higher than that of RFe$$_{2}$$O$$_{4}$$ (T$$_{N}$$ about 230-250 K). Observation of spin glass and exchange bias shows a coexistence of ferromagnetic and antiferromagneticinteractions, similarly to RFe$$_{2}$$O$$_{4}$$. This situation gives rise to a complex magnetic change and a broad peak of magnetic entropy change. Some characteristics, such as refrigeration temperatures higher than in RFe$$_{2}$$O$$_{4}$$, seem to offer a possibility of this system to applications.

Journal Articles

Magnetic properties of single crystalline YbFe$$_{2}$$O$$_{4}$$

Yoshii, Kenji; Mizumaki, Masaichiro*; Matsumoto, Keisuke*; Mori, Shigeo*; Endo, Naruki; Saito, Hiroyuki; Matsumura, Daiju; Kambe, Takashi*; Ikeda, Naoshi*

Journal of Physics; Conference Series, 428, p.012032_1 - 012032_5, 2013/04

 Times Cited Count:12 Percentile:2.16

We have investigated a single crystal of multiferroic YbFe$$_{2}$$O$$_{4}$$. Its magnetic transition temperature was 250 K. The magnetization along the c-axis was much larger than that within the ab plane, indicating the Ising character of this system. The field-cooled magnetization became negative below 10 K. This was explained in terms of an antiparallel coupling between Yb and Fe moments. Magnetocaloric effects were also observed. The change of entropy was found to show a broad peak with a width of 100 K, which is favorable to application.

Journal Articles

Exchange bias in multiferroic $$R$$Fe$$_{2}$$O$$_{4}$$ ($$R$$=Y, Er, Tm, Yb, Lu and In)

Yoshii, Kenji; Ikeda, Naoshi*; Nishihata, Yasuo; Maeda, Daisuke*; Fukuyama, Ryota*; Nagata, Tomoko*; Kano, Jun*; Kambe, Takashi*; Horibe, Yoichi*; Mori, Shigeo*

Journal of the Physical Society of Japan, 81(3), p.033704_1 - 033704_4, 2012/03

 Times Cited Count:10 Percentile:42.2(Physics, Multidisciplinary)

Exchange bias (EB) behavior has been observed for multiferroic $$R$$Fe$$_{2}$$O$$_{4}$$ ($$R$$=Y, Er, Tm, Yb, Lu and In). The materials with the small $$R$$$$^{3+}$$ ions ($$R$$=Tm, Yb, Lu and In) exhibit large EB fields ($$_sim^{>}$$ 1 kOe) below $$sim$$100-150 K. This property is rooted in a magnetically glassy state, arising from the competition between ferro- and antiferromagnetic domain interactions. In addition, the exchange bias field tends to be more enhanced for smaller $$R$$$$^{3+}$$ ions. Hence, the EB is controlled by the substitution at the $$R$$-site in this series.

Journal Articles

Doping effect on charge ordered structure in Mn-doped YbFe$$_{2}$$O$$_{4}$$

Matsumoto, Keisuke*; Koyama, Tsukasa*; Mori, Shigeo*; Yoshii, Kenji; Kambe, Takashi*; Ikeda, Naoshi*

IOP Conference Series; Materials Science and Engineering, 18(9), p.092047_1 - 092047_4, 2011/09

 Times Cited Count:0 Percentile:100

Changes of charge ordered (CO) structure by partial substitution of Mn for Fe in YbFe$$_{2}$$O$$_{4}$$ were investigated by a transmission electron microscope (TEM), incombination with conventional dielectric measurement. It is revealed that partial substitution of Mn$$^{2+}$$ for Fe$$^{2+}$$ in YbFe$$_{2}$$O$$_{4}$$ destroyed drastically the CO structure with the wave vector of q=$$<$$1/3 1/3 1/2$$>$$. Consequently polar clustering structure giving rise to honeycomb-shaped diffuse streaks was found in YbFeMnO$$_{4}$$. The random distribution of polar clustering structure gives rise to characteristic broad dielectric dispersion.

Journal Articles

Collapsing processes of charge ordered structure in charge- and spin- frustrated ferrite YbFe$$_{2}$$O$$_{4}$$

Matsumoto, Keisuke*; Koyama, Tsukasa*; Mori, Shigeo*; Yoshii, Kenji; Ikeda, Naoshi*

Journal of Physics; Conference Series, 320, p.012085_1 - 012085_5, 2011/09

 Times Cited Count:0 Percentile:100

In order to clarify the stability of charge ordered structure (CO) in charge- and spinfrustrated ferrite YbFe$$_{2}$$O$$_{4}$$, we have investigated changes of the CO structure by partial substitution of Mn$$^{2+}$$ for Fe$$^{2+}$$ in YbFe$$_{2}$$O$$_{4}$$ by a transmission electron microscope (TEM), incombination with conventional dielectric measurement. It is revealed that subtle substitution of Mn$$^{2+}$$ for Fe$$^{2+}$$ in YbFe$$_{2}$$O$$_{4}$$ destroyed drastically the CO structure with the wave vector of q=$$<$$1/3 1/3 1/2$$>$$ and, instead, induced polar clustering structure characterized by honeycomb shaped diffuse scatterings in the reciprocal space. The formation of polar clustering structure should be responsible for the characteristic dielectric dispersion.

Journal Articles

Direct observation of low-temperature superstructure in spin- and charge-frustrated ferrite YFe$$_{2}$$O$$_{4-delta}$$

Horibe, Yoichi*; Ikeda, Naoshi*; Yoshii, Kenji; Mori, Shigeo*

Physical Review B, 82(18), p.184119_1 - 184119_5, 2010/11

 Times Cited Count:7 Percentile:61.91(Materials Science, Multidisciplinary)

The low-temperature superstructure of YFe$$_{2}$$O$$_{4-delta}$$ was carefully investigated by transmission electron microscopy. We found that the unique superstructure at about 100 K is characterized by $$bar{1}$$/14 2/7 1/14-type superlattice reflection spots, suggesting the presence of charge reordering process. The low-temperature high-resolution images clearly show superlattice modulations in Y-O layers as well as Fe-O layers. The modification of intra-bilayer charge interactions due to lattice distortions in Y-O layers is discussed to play a crucial role in the stabilization of long-periodic superstructures at low temperatures.

Journal Articles

Lorentz transmission electron microscopy observation of magnetic domains in La$$_{0.825}$$Sr$$_{0.175}$$(Mn,Al)O$$_{3}$$

Mori, Shigeo*; Yoshidome, Kazuhiro*; Nagamine, Yuki*; Togawa, Yoshihiko*; Yoshii, Kenji; Takenaka, Koshi*

Journal of Applied Physics, 107(9), p.09D306_1 - 09D306_3, 2010/05

 Times Cited Count:0 Percentile:100(Physics, Applied)

Nonmagnetic Al substitution effect on the stability of a ferromagnetic (FM) metallic state indouble-exchange manganite, La$$_{0.825}$$Sr$$_{0.175}$$MnO$$_{3}$$, was investigated by Lorentz transmission electronmicroscopy (TEM), in combination with magnetic measurements. Both FM transition temperature(Tc) and the rhombohedral-to-orthorhombic (R-to-O) transition temperature (Ts) decreased by a few percent of Al substitution. An in situ Lorentz TEM observation revealed that drastic change of the FM domain structure took place through the R-to-O structural transition. The magnetization decreased slightly at Ts and characteristic spin-glass state is realized in the low-temperature region below Ts.

Journal Articles

Doping effect on charge ordered structure in RFe$$_{2}$$O$$_{4}$$(R=Lu and Yb)

Matsuo, Yoji*; Mori, Shigeo*; Hirata, Akihiko*; Yoshii, Kenji; Ikeda, Naoshi*

Journal of Physics; Conference Series, 200, p.012128_1 - 012128_4, 2010/02

 Times Cited Count:3 Percentile:20.87

RFe$$_{2}$$O$$_{4}$$ (R= Ho-Lu,Y) is a novel ferroelectric material in which ferroelectric polarization is caused by the charge ordering (CO) of Fe$$^{2+}$$ and Fe$$^{3+}$$. In this work we investigated the CO structure and dielectric/magnetic properties in RFe$$_{2}$$O$$_{4}$$ and RFeCuO$$_{4}$$ (R=Lu,Yb, M=Cu,Co) by a transmission electron microscopy (TEM), combining with dielectric and magnetic measurements. LuFeCuO$$_{4}$$ is a dielectric compound, which shows the characteristic low-frequency dielectric dispersion. In addition, the Cu$$^{2+}$$ substitution in LuFe$$_{2}$$O$$_{4}$$ suppressed the formation of the CO structure and induced characteristic polar nanodomains with the 5-10nm size. Magnetic measurement revealed that LuFeCuO$$_{4}$$ shows the magnetic transition around 50K, which is much lower than the magnetictransition temperature of 250K in LuFe$$_{2}$$O$$_{4}$$. Our experimental results suggest that the polar nanodomains should be responsible for the magnetic/dielectric properties in RFeMO$$_{4}$$.

Journal Articles

Magnetic properties and ferromagnetic microstructures in Al-doped La$$_{1-x}$$Sr$$_{x}$$MnO$$_{3}$$

Mori, Shigeo*; Yoshidome, Kazuhiro*; Nagamine, Yuki*; Togawa, Yoshihiko*; Yoshii, Kenji; Takenaka, Koshi*

Journal of Physics; Conference Series, 200, p.012129_1 - 012129_4, 2010/02

 Times Cited Count:5 Percentile:11.97

Doping effect on ferromagnetic (FM) properties in perovskite manganites La$$_{1-x}$$Sr$$_{x}$$MnO$$_{3}$$ (x=0.175) were investigated by low-temperature Lorentz transmission electron microscopy (TEM), in combination with the conventional magnetic measurements. It is found that La$$_{0.825}$$Sr$$_{0.175}$$Mn$$_{0.95}$$Al$$_{0.05}$$O$$_{3}$$ exhibits a structural phase transition from the rhombohedral to orthorhombic structures at Ts$$sim$$116 K. During the rhombohedral-to-orthorhombic transition, the FM domain structures changed from the macroscopic FM domains to the FM ones with the wavy stripe pattern. The ac magnetic measurements also revealed that La$$_{0.825}$$Sr$$_{0.175}$$Mn$$_{0.95}$$Al$$_{0.05}$$O$$_{3}$$ shows unconventional magnetic behaviour at low temperature below 65 K. Partial substitution of non-magnetic Al$$^{3+}$$ for Mn$$^{3+}$$ has some influence on magnetic ordering and double-exchange interaction, which should induce insulator behaviour in the orthorhombic phase.

Journal Articles

Structural characterization and dielectric properties of hexagonal Lu(Fe,Ti)O$$_{3}$$

Matsuo, Yoji*; Hoshiyama, Takuya*; Mori, Shigeo*; Yoshii, Kenji; Michiue, Yuichi*; Kambe, Takashi*; Ikeda, Naoshi*; Brown, F.*; kimizuka, noboru*

Japanese Journal of Applied Physics, 48(9), p.09KB04_1 - 09KB04_3, 2009/10

 Times Cited Count:1 Percentile:93.94(Physics, Applied)

We have investigated an average crystal structure and microstructures in LuFe$$_{0.56}$$Ti$$_{0.44}$$O$$_{3}$$ by the transmission electron microscopy (TEM), in combination with the dielectric measurements. In this work, high-qualitypolycrystalline samples of LuFe$$_{0.56}$$Ti$$_{0.44}$$O$$_{3}$$ were successfully synthesized in air by the conventional solid state reaction. The average crystal structure at room temperature is characterized by the hexagonal structure (space group: $$P$$6$$_{3}$$ cm). Dielectric measurements revealed that LuFe$$_{0.56}$$Ti$$_{0.44}$$O$$_{3}$$ shows broad dielectric dispersion around 570 K, which should originate from the formation of the polar domain structures on the nanometer scale.

Journal Articles

Oxygen-deficient effect on charge ordering in spin- and charge-frustrated ferrite YFe$$_{2}$$O$$_{4-delta}$$

Horibe, Yoichi*; Yoshii, Kenji; Ikeda, Naoshi*; Mori, Shigeo*

Physical Review B, 80(9), p.092104_1 - 092104_4, 2009/09

 Times Cited Count:14 Percentile:43.51(Materials Science, Multidisciplinary)

The effects of oxygen deficiency on charge ordering were investigated by transmission electron microscopy at various deficiencies and temperatures of YFe$$_{2}$$O$$_{4-delta}$$. We found that the detailed nature of the charge ordering structures is associated with changes in the superlattice reflections and diffuse scattering. They go from (1/3 1/3 1/2)-type superlattice reflection to (1/3 1/3 ${it l}$)-type straight-type diffuse scattering, then to zigzag-type diffuse scattering. With the oxygen deficiencies increased, the interchange correlation of Fe-O bilayers obviously decreases, yet the triple super periodicity along [110]$$^{*}$$ remains unchanged. These findings on frustrated ferritesindicate the stability of in-plane threefold charge ordering and the importance of the interchange interaction between bilayers in the structural phase transitions.

Journal Articles

Nanometer-sized domain structures in LuFe$$M$$O$$_{4}$$ ($$M$$=Cu, Co) revealed by energy-filtered transmission electron microscopy

Matsuo, Yoji*; Hirata, Akihiko*; Horibe, Yoichi*; Yoshii, Kenji; Ikeda, Naoshi*; Mori, Shigeo*

Ferroelectrics, 380(1), p.56 - 62, 2009/06

 Times Cited Count:6 Percentile:67.43(Materials Science, Multidisciplinary)

Diluted effect on the charge ordered (CO) structure in dielectric materials LuFe$$M$$O$$_{4}$$ ($$M$$=Cu, Co) were investigated by an energy-filtered transmission electron microscope (TEM), in combination with a conventional TEM. It is revealed that partial substitution of Cu$$^{2+}$$ and Co$$^{2+}$$ for Fe$$^{2+}$$ in LuFe$$_{2}$$O$$_{4}$$ destabilized the CO structure. In LuFeCuO$$_{4}$$, there exist characteristic zigzag-shaped diffuse streaks and diffuse spots at the h/3-$$delta$$ h/3-$$delta$$ 0-type positions (h: integer, $$delta$$=0.06) in reciprocal space, which originate from static cationic ordering of Fe$$^{3+}$$ and Cu$$^{2+}$$ ions in the triangular lattice. Moreover, real-space images by the energy-filtered TEM revealed that nanometer-sized domain structures with the 5$$sim$$10 nm size are formed. In contrast, honeycomb-shaped diffuse streaks were found in LuFeCoO$$_{4}$$, in which no domain structures are observed in real-space images.

Journal Articles

Magnetic and dielectric properties of YbFe$$_{2-x}$$Mn$$_{x}$$O$$_{4}$$ (0$$underline{<}$$x$$underline{<}$$1)

Yoshii, Kenji; Ikeda, Naoshi*; Michiuchi, Takamasa*; Yokota, Yusuke*; Okajima, Yuka; Yoneda, Yasuhiro; Matsuo, Yoji*; Horibe, Yoichi*; Mori, Shigeo*

Journal of Solid State Chemistry, 182(7), p.1611 - 1618, 2009/06

 Times Cited Count:12 Percentile:51.51(Chemistry, Inorganic & Nuclear)

We have investigated the magnetic and dielectric properties of YbFe$$_{2-x}$$Mn$$_{x}$$O$$_{4}$$ (0$$underline{<}$$x$$underline{<}$$1), which is an Fe-site-substituted system of new multiferroic oxides RFe$$_{2}$$O$$_{4}$$ (R=Y, Ho-Lu). X-ray diffraction measurements show that a solid solution is formed between YbFe$$_{2}$$O$$_{4}$$ (x=0) and YbFeMnO$$_{4}$$ (x=1) for 0$$underline{<}$$x$$underline{<}$$1. The valence of the Mn ion is determined to be $$sim$$2+, consistently with the suppression of low-temperature magnetization by the Mn substitution. The magnetic transition temperature and the dielectric constant decrease monotonically with increasing x. This result plausibly confirms that the magnetic and dielectric properties in oxides isostructural with RFe$$_{2}$$O$$_{4}$$ are governed by the electron transfer between Fe-site ions, unlike ordinary ferroelectrics and dielectrics, in which the ionic displacement plays a key role. The possibility for application is briefly discussed.

63 (Records 1-20 displayed on this page)