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Journal Articles

Origin of magnetovolume effect in a cobaltite

Miao, P.*; Tan, Z.*; Lee, S. H.*; Ishikawa, Yoshihisa*; Torii, Shuki*; Yonemura, Masao*; Koda, Akihiro*; Komatsu, Kazuki*; Machida, Shinichi*; Sano, Asami; et al.

Physical Review B, 103(9), p.094302_1 - 094302_18, 2021/03

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

The layered perovskite PrBaCo$$_{2}$$O$$_{5.5}$$ demonstrates a strong negative thermal expansion (NTE) which holds potential for being fabricated into composites with zero thermal expansion. The NTE was found to be intimately associated with the spontaneous magnetic ordering, known as magneto-volume effect (MVE). Here we report with compelling evidences that the continuous-like MVE in PrBaCo$$_{2}$$O$$_{5.5}$$ is intrinsically of discontinuous character, originating from an magnetoelectric transition from an antiferromagnetic insulating large-volume (AFILV) phase to a ferromagnetic less-insulating small-volume (FLISV) phase. Furthermore, the magnetoelectric effect (ME) shows high sensitivity to multiple external stimuli such as temperature, carrier doping, hydrostatic pressure, magnetic field etc. In contrast to the well-known ME such as colossal magnetoresistance and multi-ferroic effect which involve symmetry breaking of crystal structure, the ME in the cobaltite is purely isostructural. Our discovery provides a new path way to realizing the ME as well as the NTE, which may find applications in new techniques.

Journal Articles

Strong flux pinning by columnar defects with directionally dependent morphologies in GdBCO-coated conductors irradiated with 80 MeV Xe ions

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Fujiyoshi, Takanori*; Semboshi, Satoshi*; Ozaki, Toshinori*; Sakane, Hitoshi*; Kudo, Masaki*; Yasuda, Kazuhiro*; Ishikawa, Norito

Japanese Journal of Applied Physics, 59(2), p.023001_1 - 023001_7, 2020/02

 Times Cited Count:3 Percentile:58.93(Physics, Applied)

We show that Xe ion irradiation with 80 MeV to GdBa$$_{2}$$Cu$$_{3}$$Oy-coated conductors creates different morphologies of columnar defects (CDs) depending on the irradiation angles relative to the c-axis: continuous CDs with a larger diameter are formed for oblique irradiation at $$theta_{rm i}$$ = 45$$^{circ}$$, whereas the same ion beam at a different angle ($$theta_{rm i}$$ = 0$$^{circ}$$) induces the formation of discontinuous CDs. The direction-dependent morphologies of CDs significantly affect the angular behavior of the critical current density $$J_{rm c}$$.

Journal Articles

Rock mass property evaluation based on the borehole wall images taken by using an ultrasonic scanner (USS)

Otsuka, Yasunori*; Ishikawa, Takanori*; Tajima, Katsuhiro*; Wada, Tetsu*; Aydan, $"O$mer*; Tokashiki, Naohiko*; Sato, Toshinori; Aoyagi, Kazuhei

Journal of Nepal Geological Society, 55(Special Issue), p.1 - 6, 2018/00

Ultrasonic wave reflection intensity of the wall of borehole drilled from bottom of the East Access Shaft in the Horonobe Underground Research Laboratory, Hokkaido, Japan, was obtained using an ultrasonic scanner (USS). In this paper, we compared results of USS observation with core logging data including core observation, optical digital scanner (ODS) observation, and result of Needle Penetration Index (NPI) tests. The results indicated that ultrasonic wave reflection intensity had a good correlation with other observation results. USS observation and NPI tests are useful techniques for determination of detailed rock mass classification.

Journal Articles

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Journal Articles

Flux pinning properties in YBCO films with growth-controlled nano-dots and heavy-ion irradiation defects

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Uraguchi, Yusei*; Suenaga, Momotaro*; Makihara, Takahiro*; Fujiyoshi, Takanori*; Ishikawa, Norito

Physica C, 530, p.72 - 75, 2016/11

 Times Cited Count:6 Percentile:32.3(Physics, Applied)

In order to clarify the influence of size and spatial distribution of three-dimensional pinning centers (3D-PCs) on hybrid flux pinning, columnar defects (CDs) were installed by using 200 MeV Xe ions along the $$c$$-axis direction into quasi-multilayered films consisting of YBa$$_{2}$$Cu$$_{3}$$Oy layers and pseudo layers of BaSnO$$_{3}$$. The positive effect of the BaSnO$$_{3}$$ doping on the hybrid flux pinning stands out for the critical current density $$J_{rm c}$$ around $$B parallel c$$ in high magnetic field and/or inclined magnetic field off the $$c$$-axis, whereas there is little difference in the $$J_{rm c}$$ at $$B parallel c$$ among the same growth temperature samples for low magnetic field. In the case of the in-plane distributed BaSnO$$_{3}$$ nano-dots, the Jc around $$B parallel ab$$ is remarkably enhanced, whereas there is a detrimental effect on the Jc around $$B parallel c$$. These imply that the tuning of 3D-PCs is one of the keys to improve the $$J_{rm c}$$ at all magnetic field orientations for the hybrid flux pinning.

Journal Articles

High flux pinning efficiency by columnar defects dispersed in three directions in YBCO thin films

Sueyoshi, Tetsuro*; Nishimura, Takahiro*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito

Superconductor Science and Technology, 29(10), p.105006_1 - 105006_7, 2016/10

 Times Cited Count:7 Percentile:41.71(Physics, Applied)

A systematic investigation of flux pinning by widely direction-dispersed columnar defects (CDs) in YBa$$_{2}$$Cu$$_{3}$$Oy thin films was carried out by using heavy-ion irradiation: a parallel configuration of CDs aligned along the $$c$$-axis, and two trimodal splay configurations composed of crossing CDs; relative to the $$c$$-axis, where the splay plane defined by the three irradiation angles is perpendicular (trimodal-A) or parallel (trimodal-B) to the transport current direction. The trimodal configurations show high pinning efficiency over a wide range of magnetic field orientations compared to the parallel one at low magnetic field. In particular, trimodal-B shows the higher critical current density of the two trimodal configurations.

Journal Articles

Flux pinning properties in GdBCO coated conductors containing columnar defects with splay plane parallel to current direction

Furuki, Yuichi*; Sueyoshi, Tetsuro*; Kai, Takashi*; Iwanaga, Yasuya*; Fujiyoshi, Takanori*; Ishikawa, Norito

Physica C, 518, p.58 - 62, 2015/11

 Times Cited Count:4 Percentile:23.3(Physics, Applied)

In order to reveal the influence of crossing angle of one-dimensional pinning centers on angular dependence of critical current density Jc, heavy-ion irradiation was performed to introduce columnar defects (CDs) crossing relative to the c-axis into GdBCO coated conductors, where the splay plane consisting of the two directions of CDs is parallel to the current flow direction. For the sample containing CDs with 15$$^{circ}$$, a single and sharp peak was observed around B$$||$$c in the angular dependence of Jc. When the crossing angle was extended to 45$$^{circ}$$, the single Jc-peak became broader, which was a gently-sloping mountain-like shape centered at B$$||$$c. For 75$$^{circ}$$, on the other hand, a quite different behaviour of Jc from the other irradiated samples was observed, which was analogous to the angular dependence of Jc typical of three dimensional pinning centers.

Journal Articles

Influence of discontinuous columnar defects on flux pinning properties in GdBCO coated conductors

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Uraguchi, Yusei*; Kai, Takashi*; Fujiyoshi, Takanori*; Shimada, Yusuke*; Yasuda, Kazuhiro*; Ishikawa, Norito

IEEE Transactions on Applied Superconductivity, 25(3), p.6603004_1 - 6603004_4, 2015/06

 Times Cited Count:7 Percentile:44.18(Engineering, Electrical & Electronic)

To investigate the effect of discontinuity of 1-D pinning centers on the flux pinning in a wide range of magnetic field directions, discontinuous columnar defects (CDs) and continuous CDs were formed in GdBCO coated conductors using Xe-ion irradiations with 80 and 270 MeV, respectively. An overall shift upward in Jc, for the 80-MeV-irradiated sample compared to the 270-MeV-irradiated one, can be observed in every direction of magnetic field, which is more remarkable as temperature decreases. This implies a synergetic effect of the pinning interaction between the linearity and the discontinuity for the discontinuous CDs.

Journal Articles

Angular dependence of critical current density and $$n$$-values in BaZrO$$_{3}$$/YBa$$_{2}$$Cu$$_{3}$$O$$_{y}$$ quasi-multilayered films with columnar defects

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito

Physica C, 494, p.153 - 157, 2013/11

 Times Cited Count:5 Percentile:28.48(Physics, Applied)

BaZrO$$_{3}$$/YBa$$_{2}$$Cu$$_{3}$$Oy quasi-multilayered films, in which the size and the spatial distribution of BaZrO$$_{3}$$ nano-particles were controlled, were irradiated using 200 MeV Xe ions along the c-axis direction. Whenthe BaZrO$$_{3}$$ nano-particles were larger in size, the flux lines not captured by CDs, such as interstitial fluxlines between CDs and double kinks of flux lines, can be pinned more effectively by the BaZrO$$_{3}$$ nano-particles, so that the Jc enhances for high magnetic fields and high temperature. In addition, the inverse correlation between Jc and n-value appears at high temperature in increasing magnetic field for the film with correlated rows of the nano-particles which might be curved off the c-axis. These suggest that the hybrid flux pinning depends not only on the combination of one-dimensional (1D) and three-dimensional pinning centers (3D-PCs) but also on the size and the spatial distribution of the 3D-PCs.

Journal Articles

Research and development of radiation measuring instruments for lake,pond and river sediments, 1

Yanagizawa, Koichi; Hayashi, Toshio*; Oinuma, Masaru*; Takemori, Makoto*; Ishikawa, Takanori*; Okaya, Tomoichi*; Nishigaki, Makoto*

Shadan Hojin Butsuri Tansa Gakkai Dai-129-Kai (Heisei-25-Nendo Shuki) Gakujutsu Koenkai Koen Rombunshu, p.287 - 288, 2013/10

The development of instrument aimed at the measurement of radiation dose in the sediment of lakes, rivers and sea bed been carried out. The radiation level contained in the sediment at the bottom of lake and so on is anticipated to indicate the existence of locally high radiation spots where the diffused radioactive substance is accumulated in ponds, rivers and lakes by rainwater. The radiation dose measurement system this time is to measure $$gamma$$-ray by dragging the detector, which is called probe, at the bottom of lakes to understand the radiation dose over wide areas. Furthermore, the measurement of resistivity value at the bottom of lakes is simultaneously dose to presume the condition of sediment.

Journal Articles

Angular dependence of critical current density in YBCO films with columnar defects crossing at widespread angles

Sueyoshi, Tetsuro*; Furuki, Yuichi*; Tanaka, Eiki*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito

IEEE Transactions on Applied Superconductivity, 23(3), p.8002404_1 - 8002404_4, 2013/06

 Times Cited Count:8 Percentile:46.11(Engineering, Electrical & Electronic)

To investigate whether one dimensional pinning centers (1D PCs) can attain the isotropic critical current density ($$J_{c}$$) properties, columnar defects (CDs) crossing at widespread angles were installed by heavy-ion irradiations into YBCO thin films. For the sample containing the CDs crossing relative to the $$c$$-axis, the plateau-like behavior of $$J$$$$_{c}$$ is realized over a wide range of magnetic field orientations, except for around B $$||$$ $$ab$$-plane where a dip structure is accompanied by a rapid decline of the $$J_{c}$$. For the bimodal splay configuration consisting of CDs crossing relative to the $$c$$-axis, a single peak around the $$c$$-axis is observed in the angular dependence of $$J_{c}$$, suggesting the splay effect at B $$||$$ $$c$$-axis by the crossed CDs. Two parallel families of CDs crossing relative to the $$ab$$-plane, on the other hand, bring about not a peak but a dip around B $$||$$ $$ab$$-plane on the angular dependence of $$J_{c}$$.

JAEA Reports

Probabilistic safety assessment on experimental fast reactor Joyo; Level1 PSA for internal events

Ishikawa, Koki; Takamatsu, Misao; Kawahara, Hirotaka; Mihara, Takatsugu; Kurisaka, Kenichi; Terano, Toshihiro; Murakami, Takanori; Noritsugi, Akihiro; Iseki, Atsushi; Saito, Takakazu; et al.

JAEA-Technology 2009-004, 140 Pages, 2009/05


Probabilistic safety assessment (PSA) has been applied to nuclear plants as a method to achieve effective safety regulation and safety management. In order to establish the PSA standard for fast breeder reactor (FBR), the FBR-PSA for internal events in rated power operation is studied by Japan Atomic Energy Agency (JAEA). The level1 PSA on the experimental fast reactor Joyo was conducted to investigate core damage probability for internal events with taking human factors effect and dependent failures into account. The result of this study shows that the core damage probability of Joyo is 5.0$$times$$10$$^{-6}$$ per reactor year (/ry) and that the core damage probability is smaller than the safety goal for existed plants (10 ry) and future plants (10$$^{-5}$$/ry) in the IAEA INSAG-12 (International Nuclear Safety Advisory Group) basic safety principle.

Journal Articles

Chemical form of released tritium from solid breeder materials under the various purge gas conditions

Kinjo, Tomohiro*; Nishikawa, Masabumi*; Yanashita, Naoya*; Koyama, Takanori*; Tanifuji, Takaaki*; Enoeda, Mikio

Fusion Engineering and Design, 82(15-24), p.2147 - 2151, 2007/10

 Times Cited Count:19 Percentile:79.3(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Measurement of self-diffusion coefficients in Li ionic conductors by using the short-lived radiotracer of $$^8$$Li

Jeong, S.-C.*; Katayama, Ichiro*; Kawakami, Hirokane*; Watanabe, Yutaka*; Ishiyama, Hironobu*; Imai, Nobuaki*; Hirayama, Yoshikazu*; Miyatake, Hiroari; Sataka, Masao; Okayasu, Satoru; et al.

Journal of Phase Equilibria and Diffusion, 26(5), p.472 - 476, 2005/09

Authors developed a radiotracer method for diffusion studies in solids. The experimental test was performed by the measurement of the diffusion coefficients of Li in a sample of the compound $$beta$$LiAl using an $$alpha$$-emitting radiotracer of $$^8$$Li(T$$_{1/2}$$ = 0.84 s). It was found that the time-dependent yields of the alpha particles from the diffusing 8Li that was initially implanted in the sample could be used as a measure of the diffusivity of the tracer in a nondestructive way. The method was applied to measure the self-diffusion coefficients of Li in $$beta$$LiGa, and for investigating how the Li diffusion in the Li ionic conductors is affected by the concentration of atomic defects.

Journal Articles

Measurement of diffusion coefficients in solids by the short-lived radioactive beam of $$^{8}$$Li

Jeong, S.-C.*; Katayama, Ichiro*; Kawakami, Hirokane*; Watanabe, Yutaka*; Ishiyama, Hironobu*; Miyatake, Hiroari*; Sataka, Masao; Okayasu, Satoru; Sugai, Hiroyuki; Ichikawa, Shinichi; et al.

Nuclear Instruments and Methods in Physics Research B, 230(1-4), p.596 - 600, 2005/04

 Times Cited Count:6 Percentile:46.82(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Critical current density of YBa$$_{2}$$Cu$$_{3}$$O$$_{y}$$ containing inclined columnar defects

Ishikawa, Norito; Sueyoshi, Tetsuro*; Iwase, Akihiro; Chimi, Yasuhiro; Fujiyoshi, Takanori*; Miyahara, K.*; Kisu, T.*

Physica C, 357-360(Part.1), p.505 - 508, 2001/09

no abstracts in English

Oral presentation

Integration and verification of tritium release model in thermo-hydraulic analysis code

Seki, Yohji; Hirose, Takanori; Yoshikawa, Akira; Enoeda, Mikio; Fukada, Satoshi*; Nishikawa, Masabumi*; Kinjo, Tomohiro*

no journal, , 

no abstracts in English

Oral presentation

Change in various properties induced by swift heavy ion irradiation in CeO$$_{2}$$

Kishino, Takanori*; Shimizu, Hirotaka*; Hori, Fuminobu*; Iwase, Akihiro*; Ishikawa, Norito; Okamoto, Yoshihiro; Saito, Yuichi

no journal, , 

In the present experiment, to obtain the fundamental knowledge of radiation effects on CeO$$_{2}$$, CeO$$_{2}$$ pellets and films were irradiated with various energetic ions. To evaluate the effect of high energy ion irradiation on CeO$$_{2}$$, we have used a con-ventional X-ray diffraction (XRD), Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), and SQUID magne-tometer. In this symposium, we discuss the effects of ion irradiation on CeO$$_{2}$$.

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