TEION KOGAKU 50th Year Commemorative Articles
Preface.........Kenichi SATO      1
TEION KOGAKU 50th Year Commemorative Articles.........Atsushi ISHIYAMA      2
50 Years of TEION KOGAKU.........Yoshitane AKIYAMA      4

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The development of rare earth (RE) Ba₂Cu₃O_y (REBCO) coated conductors has been carried out by many groups. The critical current density (J_c) in high magnetic fields needs to be improved for superconducting applications. We have fabricated BaHfO₃ (BHO)-doped SmBa₂Cu₃O_y films on ion beam-assisted deposition (IBAD)-MgO substrates using pulsed laser deposition (PLD). In this study, we introduce a seed layer technique. As a result, the appropriate growth temperature (T_s) is expanded to higher temperature range without BaCeO₃ outgrowth around the interface of the SmBCO and CeO₂ cap-layer. We were able to control the configurations of the BHO nanorods within the SmBCO films as compared to the conventional PLD method. The SmBCO + BHO (1.4 vol.%) films, which were fabricated at a T_s^upper of 900ºC, showed that the J_c in the magnetic field (B // c) was improved as compared to pure-SmBCO films. Furthermore, the global pinning force density reached 21 GN/m^-3 at 77 K in B = 2 T.

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Recently, high-temperature, superconducting coated conductors (CCs) are being used for various applications, and further improvement of the in-field transport property is required. In order to improve the magnetic field and angular dependences, introducing artificial pinning centers (APC) into the superconducting layer is known to be effective. Moreover, it is necessary to fabricate long CCs while maintaining excellent properties in order to reduce manufacturing costs. We succeeded in achieving the above-mentioned issues by using trifluoloacetate solution metal organic deposition (TFA-MOD), and fabricated a long Y_0.77Gd_0.23Ba₂Cu₃O_y (YGdBCO) + BaZrO₃ (BZO) CC using batch furnace heat treatment. We also confirmed the superior infield performance of this CC through transport measurements.

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