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single crystals and its characterizationIshikado, Motoyuki; Shamoto, Shinichi; Kito, Hijiri*; Iyo, Akira*; Eisaki, Hiroshi*; Ito, Toshimitsu*; Tomioka, Yasuhide*
Physica C, 470(Suppl.1), p.S322 - S323, 2010/12
Times Cited Count：3 Percentile：17.17(Physics, Applied)Single crystals of oxygen deficient oxypnictide superconductor PrFeAsO have been grown by using belt-type anvil high pressure synthesis apparatus. Superconducting transition temperature (
) of the obtained single crystal is 45 K, and typical size is about 800 
1000 30 
. In-plane electrical resistivity shows almost proportional to temperature as well as the copper oxide high temperature superconductors, suggesting the existence of effects of strong inelastic scattering like copper oxide high temperature superconductor. In addition, we obtained non-superconducting parent single crystal by annealing the as-grown single crystal under ambient pressure. Resistivity of parent single crystal is characterized by the kink near 150 K corresponding to the structural transition, and the structure near 12 K, which is thought to be originating from the magnetic order of Pr ion.
FeAsO ( = La and Nd) obtained from charge transport experimentsIshida, Shigeyuki*; Nakajima, Masamichi*; Tomioka, Yasuhide*; Ito, Toshimitsu*; Miyazawa, Kiichi*; Kito, Hijiri*; Lee, C.-H.*; Ishikado, Motoyuki; Shamoto, Shinichi; Iyo, Akira*; et al.
Physical Review B, 81(9), p.094515_1 - 094515_6, 2010/03
Times Cited Count：21 Percentile：64.67(Materials Science, Multidisciplinary)Characteristic normal-state charge transport is found in the oxygen-deficient iron-arsenides FeAsO (: La and Nd) with the highest 
's among known Fe-based superconductors. The effect of "doping" in this system is mainly on the carrier scattering, quite distinct from that in high- cuprates. In the superconducting regime of the La system with maximum = 28 K, the low-temperature resistivity is dominated by a 
term. On the other hand, in the Nd system with higher than 40 K, the carriers are subject to stronger scattering showing -linear resistivity and small magnetoresistance. Such strong scattering appears crucial for high- superconductivity in the iron-based system.
and its characterizationIshikado, Motoyuki; Shamoto, Shinichi; Kito, Hijiri*; Iyo, Akira*; Eisaki, Hiroshi*; Ito, Toshimitsu*; Tomioka, Yasuhide*
Physica C, 469(15-20), p.901 - 904, 2009/10
Times Cited Count：23 Percentile：66.35(Physics, Applied)We have successfully grown single crystals of oxygen deficient oxypnictide superconductor PrFeAsO by belt-type anvil apparatus using high pressure synthesis method.
Shirage, P. M.*; Miyazawa, Kiichi*; Ishikado, Motoyuki; Kiho, Kunihiro*; Lee, C.-H.*; Takeshita, Nao*; Matsuhata, Hirofumi*; Kumai, Reiji*; Tomioka, Yasuhide*; Ito, Toshimitsu*; et al.
Physica C, 469(9-12), p.355 - 369, 2009/06
Times Cited Count：40 Percentile：79.94(Physics, Applied)We have utilized a high-pressure (HP) technique to synthesize a series of newly-discovered iron (nickel)-based superconductors. The effect of (O)-deficiency, variation of 
ions, and the external pressure on 
are examined. All the experimental data indicate strong correlation between the crystal structure and the superconductivity of the oxypnictide superconductors. Upper critical field measurement on single crystalline sample of PrFeAsO shows the superconducting anisotropy of 5, which is smaller than cuprates. We also demonstrate that HP technique is applicable for the so-called "122" systems.
Isono, Takaaki; Hamada, Kazuya; Kawano, Katsumi; Abe, Kanako*; Nunoya, Yoshihiko; Sugimoto, Makoto; Ando, Toshinari*; Okuno, Kiyoshi; Bono, Takaaki*; Tomioka, Akira*; et al.
Teion Kogaku, 39(3), p.122 - 129, 2004/03
JAERI has been developing a large-capacity high-temperature superconductor (HTS) current lead for fusion application, and succeeded in fabricating and testing a 60kA HTS current lead satisfying ITER requirements. Targets of performance are 1/10 heat leak and 1/3 electric power consumption of cryogenic system compared with a conventional lead. To achieve the target, selection of sheath material of HTS, optimizing the Cu part, reduction of joule heat at joint between HTS and Cu parts, improve of heat transfer between HTS and stainless steel tube. Developed 60kA HTS current lead satisfied the design condition and almost achieved the targets. Adoption of the HTS current lead can reduce 13% electric power consumption of cryogenic system for ITER.
Isono, Takaaki; Kawano, Katsumi; Hamada, Kazuya; Matsui, Kunihiro; Nunoya, Yoshihiko; Hara, Eiji*; Kato, Takashi; Ando, Toshinari*; Okuno, Kiyoshi; Bono, Takaaki*; et al.
Physica C, 392-396(Part2), p.1219 - 1224, 2003/10
A 60-kA high-temperature-superconductor (HTS) current lead has been fabricated and tested for aiming at the application to a fusion magnet system, providing a low heat leak current lead. The design of HTS current leads is optimized not only to reduce the heat leak but also to perform safe operation even in fault conditions. The HTS current lead consists of a forced flow cooled copper part and a conduction cooled HTS part. The HTS part is composed of 288 Ag-10at.%Au sheathed Bi-2223 tapes and they are cylindrically arrayed on a stainless steel tube. The diameter and the length of the HTS part are 146 mm and 300 mm, respectively. Operation of a 60 kA current, which is the world record, was successfully achieved at coolant of 20 K, 3.2 g/s for the copper part, and a low heat leak of 5.5 W at 4.2 K was demonstrated. This result shows that the electric power of a refrigerator to cool the current lead can be reduced by 1/3 of that in a conventional current lead. In conclusion, technology of a large HTS current lead for fusion application is established.
Ando, Toshinari; Isono, Takaaki; Hamada, Kazuya; Nishijima, Gen; Tsuji, Hiroshi; Tomioka, Akira*; Bono, Takaaki*; Yasukawa, Yukio*; Konno, Masayuki*; Uede, Toshio*
IEEE Transactions on Applied Superconductivity, 11(1), p.2535 - 2538, 2001/03
Times Cited Count：6 Percentile：42.23(Engineering, Electrical & Electronic)no abstracts in English
Isono, Takaaki; Hamada, Kazuya; Ando, Toshinari; Tsuji, Hiroshi; Yasukawa, Yukio*; Tomioka, Akira*; *; *; *
IEEE Transactions on Applied Superconductivity, 9(2), p.519 - 522, 1999/06
Times Cited Count：8 Percentile：51.51(Engineering, Electrical & Electronic)no abstracts in English
Kambara, Toyozo; Uno, Hidero; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Kohayakawa, Toru; Takayanagi, Hiroshi; Fujimura, Tsutomu; Morita, Morito; Ichihara, Masahiro; et al.
JAERI 1045, 11 Pages, 1963/03
no abstracts in English
and its transport propertiesIshikado, Motoyuki; Shamoto, Shinichi; Kito, Hijiri*; Iyo, Akira*; Eisaki, Hiroshi*; Ito, Toshimitsu*; Tomioka, Yasuhide*
no journal, ,
Single crystals of oxygen deficient oxypnictide superconductor PrFeAsO were grown by high pressure method using belt-type anvil apparatus. Grown crystals have shiny ab-plane surfaces. Typical crystal size is about 800100020 mm
, which is one order larger than the previous reported LnFeAs(O,F) single crystal size. Upper critical field obtained from resistivity measurement under magnetic field yields anisotropy of 
5, which is consistent with other group's reported result. In the session, we will talk details of the method of doping control of the single crystal and doping dependences of anisotropy.
and transport properties, 2Ishikado, Motoyuki; Shamoto, Shinichi; Kito, Hijiri*; Iyo, Akira*; Eisaki, Hiroshi*; Ito, Toshimitsu*; Tomioka, Yasuhide*
no journal, ,
In the previous meeting, we have grown single crystals of oxygen deficient oxypnictide high temperature superconductor PrFeAsO, and characterized anisotropy from resistivity under magnetic field. Anisotropy of upper critical field (H
) is 
5 and is consistent with other group's reported value. In this study, we succeeded to control doping by adjusting the oxygen content. We measured resistivity under magnetic field and estimated anisotropy of the doping controled single crystals, and revealed that anisotropy is not doping dependent. In the session, we report details of doping control, characterization such as resistivity and XRD, estimation of anisotropy.
Ishikado, Motoyuki; Shamoto, Shinichi; Kito, Hijiri*; Iyo, Akira*; Eisaki, Hiroshi*; Tomioka, Yasuhide*; Ito, Toshimitsu*
no journal, ,
Since the discovery of iron-based superconductor, extensive research have been done in order to clarify mechanism of superconductivity. But the research have been done mainly on 122 system because of easy availability of single crystal. So far, we have succeeded to grow single crystals of PrFeAsO high-Tc superconductor by high-pressure synthesis method. In the previous talk, we succeeded to control doping by tuning oxygen content of the single crystals, and characterized anisotropy by resistivity measurement under magnetic field. And reported that the anisotropy of iron-based superconductor dose not depend on doping different from cuprates. This time, we measure transport properties, especially for doping dependences of Hall coefficient, and discuss relationship between Hall coefficient and SDW transition on underdoping regime.
