Kyushu University Academic Staff Educational and Research Activities Database
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Takumi Suzuki Last modified date:2018.03.16

Graduate School
Undergraduate School

Measurement and Instrumentation Laboratory, Department of Electrical Engineering, Graduate School of ISEE, Kyushu University. .
Academic Degree
Doctor of Engineering
Country of degree conferring institution (Overseas)
Field of Specialization
Applied Superconductivity
Total Priod of education and research career in the foreign country
Research Interests
  • Evaluation of low temperature and high magnetic field properties in EuBCO coated conductor doped with artificial pinning center
    keyword : REBCO, Superconductor, Artificial pinning center
  • Analytical expression of in-field current transport properties in the latest commercially available Bi2223 tape
    keyword : superconductor, Bi2223
Academic Activities
1. Satoshi Awaji, Takumi Suzuki, Hidetoshi Oguro, Kazuo Watanabe, Kaname Matsumoto, Strain-controlled critical temperature in REBa2Cu3Oy-coated conductors, scientific reports, 10.1038/srep11156, 5, 11156, 2015.06, Recently, we succeeded in detwinning REBa2Cu3O7 (RE123, RE = rare-earth elements)-coated
conductors by annealing under an external uniaxial strain. Using the untwinned RE123 tapes, the
uniaxial-strain dependencies of the critical temperature Tc along the a and b crystal axes were
investigated over a wide strain region from compression to tension. We found that the strain
dependencies of Tc for the a and b axes obey a power law but exhibit opposite slopes. In particular,
the maximum value of Tc is obtained when the CuO2 plane becomes a square, and its lattice constant
is close to 0.385 nm. It is suggested that a tetragonal structure with a ≈ 0.385 nm is the optimum
condition for a high critical temperature in high-Tc cuprates..
2. Takumi Suzuki, Satoshi Awaji, Hidetoshi Oguro, Kazuo Watanabe, Applied Strain Effect on Superconducting Properties for Detwinned (Y, Gd)BCO Coated Conductors, IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, 10.1109/TASC.2014.2377577, 25, 3, 2015.06, We succeeded in the complete detwin of (Y, Gd) BCO coated conductors using a newly developed in-situ tensile apparatus at high temperature. The intensities of (020) and (200) peaks in a longitudinal and a transverse directions of the tape measured by XRD were similar to each other for usual (Y, Gd) BCO coated conductors before annealing. However, the (200) peak disappears for the longitudinal direction after annealing under the tensile stress. It means that the coated conductors are detwinned by annealing under the tensile stress. We found that T-c linearly decreases with increasing strain for the B-domain (b-axis). This behavior is similar with a uniaxial-pressure effect in (Y, Gd) BCO single crystals. However, the strain dependence of T-c for the A-domain (a-axis) behaves as a power-law function, whereas the uniaxial-pressure dependency of T-c for the a-axis is reported to be linear. In addition, the strain dependencies of J(c) are similar with those of T-c.
3. Satoshi Awaji, Takumi Suzuki, Hidetoshi Oguro, Kazuo Watanabe, Shutaro Machiya, Michinaka Sugano, Masugu Sato, Tomoyuki Koganezawa, Kaname Matsumoto, Control of residual strain and twin boundary by annealing under strain, SUPERCONDUCTOR SCIENCE & TECHNOLOGY, 10.1088/0953-2048/26/6/065013, 26, 6, 2013.06, In REBa2Cu3Oy (RE123, RE = rare earth element) coated conductors, the coexistence of a- and b-axes domains related to a twin structure is one of the origins of the complicated critical current density property and its strain dependence. Hence, control of the twin structure is a very important issue. In the case of Y123 single crystals, detwinning is widely carried out by oxygen annealing under uniaxial stress along the a/b axis. In this study, commercial RE123 superconducting tapes were oxygen-annealed under external strains, similar to the detwinning process of Y123 single crystals. We found that the volume fraction ratio of the a- and b-axis domains changes with the applied external strains during annealing, indicating a change of twin structure. In addition, the residual strains, which are strains induced from the thermal contraction difference between RE123 and the substrate, increase with compression annealing and decrease with tension annealing for RE123 tapes with [100]/[010] orientation along the tape axis. However, those phenomena by strain annealing are not obtained for the [110] oriented RE123 tapes. The strain annealing method that we propose here is very useful to control the internal residual strain and twin structures in an RE123 tape with a [100]/[010] orientation along the tape axis..
4. Takumi Suzuki, Satoshi Awaji, Hidetoshi Oguro, Kazuo Watanabe, Michinaka Sugano, Shutaro Machiya, Masugu Sato, Teruo Izumi, Yuh Shiohara, Improvement of J(c) for GdBCO Coated Conductors by Annealing Under Strain, IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, 10.1109/TASC.2012.2229376, 23, 3, 2013.06.
1. Takumi Suzuki, Lin Lyu, Syunsuke Omura, Ken Takasaki, Masayoshi Inoue, Kohei Higashikawa, Takanobu Kiss, Analytical expression of in-field current transport properties in a commercially available Bi-2223 high Tc superconducting wire, 2016 Applied Superconductivity Conference (ASC 2016), 2016.09.
2. Takumi Suzuki, Takahiro Fukuzaki, Kohei Higashikawa, Masayoshi Inoue, Takanobu Kiss, Analytical expression of local I -V characteristics for long length REBCO coated conductors under the local Ic fluctuation, 1st Asian ICMC and CSSJ 50th Anniversary Conference, 2016.11.
3. Takumi Suzuki, Takahiro Fukuzaki, Kohei Higashikawa, Masayoshi Inoue, Takanobu Kiss, Analysis of local Ic variation and I -V characteristics for long REBCO coated conductors, The 1st Asian Applied Physics Conference, 2016.12.
Membership in Academic Society
  • The Japan Society of Applied Physics
  • Cryogenics and Superconductivity Society of Japan
  • Applied strain dependence of Tc and Jc for detwinned REBCO coated conductors