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Shiohara Y.,Superconductivity Research Laboratory | Shiohara Y.,Industrial Superconductivity Technology Research Association | Nakaoka K.,Superconductivity Research Laboratory | Nakaoka K.,Industrial Superconductivity Technology Research Association | And 5 more authors.
Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals | Year: 2016

Since the discovery of the YBCO superconductor, many efforts have been made to develop useful superconductive wire and tape for many electrical power applications. Especially, the second generation coated conductors using REBaCuO (RE: rare earth element, Y, Gd, Sm, Nd, Eu etc) compounds have high expectations because of its high critical current density at the liquid nitrogen temperature and under self fields as well as high magnetic fields. Recently, several processes have been successfully developed to introduce effective magnetic flux pinning centers into the REBCO layer in order to enhance the in-field critical current densities. This paper reviews the present status of the research and development about the improvement of critical currents in considerations of nano-scale microstructure. © 2016 The Japan Institute of Metals and Materials. Source


Nakaoka K.,Industrial Superconductivity Technology Research Association | Kimura K.,Industrial Superconductivity Technology Research Association | Kato T.,Japan Fine Ceramics Center | Yoshida R.,Japan Fine Ceramics Center | And 4 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2016

A modified heat-treatment procedure, which consisted of three steps, i.e., 1) calcination, 2) intermediate heat-treatment (IHT), and 3) crystallization, was developed for the metal organic deposition method using trifluoroacetates (TFA). BaZrO3-doped Y0.77Gd0.23Ba2Cu3O6+δ (YGdBCO) coated conductors fabricated by this modified procedure provided the minimum critical current density (Jc) value of 0.21 MA/cm2 at 77 K in 3 T, which was as high as 2.1 times the value obtained by the conventional one, and a homogeneous dispersion of BaZrO3 nanoparticles with finer size in the matrix. Furthermore, the 1-D theoretical analysis of the reaction kinetics in the IHT process, considering diffusion and growth kinetics at the interface between the precursor layer and the calcined layer, was proposed, and the estimated reaction rate was compared with experimental ones. © 2002-2011 IEEE. Source


Yoshida T.,Japan International Superconductivity Technology Center | Yoshida T.,Industrial Superconductivity Technology Research Association | Ibi A.,Japan International Superconductivity Technology Center | Ibi A.,Industrial Superconductivity Technology Research Association | And 7 more authors.
Physica C: Superconductivity and its Applications | Year: 2015

Introduction of artificial pinning centers such as BaHfO3 (BHO), BaZrO3 (BZO) and BaSnO3 (BSO) into REBa2Cu3O7- δ (REBCO) coated conductor (CC) layers could improve the in-field critical currents (Ic) in wide ranges of temperatures and magnetic fields. In particular, a combination of EuBCO + BHO has been found to be effective for attaining high in-field Ic performance by means of IBAD/PLD process in short length samples. In this work, we have successfully fabricated a 93.7 m long EuBCO + BHO CC with 103 A/cm W at 77 K under a magnet field (B) of 3 T applied perpendicular to the CC (B//c). The 93.7 m long EuBCO + BHO CC had high uniformity of Ic values and n-values without any trend of fluctuations, independent of the external field up to 0.3 T. Ic-B-applied angle (θ) profiles of the 93.7 m long EuBCO + BHO CC sample showed the high in-field Ic values in all directions of applied magnetic fields especially B//c (at θ ∼ 180°, Ic = 157 A/cm W) at 77 K under 3 T. The profiles were about the same as those in a short length sample. © 2015 Elsevier B.V. Source

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