Yutaka Yoshida1

1, Nagoya University, Aichi, , Japan

We have studied from the viewpoints of high speed deposition, large area, high performance of REBa2Cu3Oy coated conductors. High performance is determinedabout by optimum shapes of the artificial pinning centers (APC) in REBa2Cu3Oy (REBCO) coated conductors towards superconducting magnets operating at temperatures of 77 K or less.and lower temperature. Superconducting properties have been changedvary depending on the by different kind and addition amountquantity of BaMO3 added to REBCO. Therefore, we study the changes in theof shapes of nanorods shapedue to the difference in theof nature of additives and growth temperature. In addition, weand aim to control the APC having anwith the optimum shape that matchesing the operating temperature.
The high flux pinning performance was obtained for a 3.8vol.% BaHfO3 (BHO)-doped SmBa2Cu3Oy (SmBCO) on IBAD-MgO. At 77.3 K, the irreversibility field (Birr) of 16.8 T and the maximum flux pinning force density (Fp) of 32.5 GN/m3 (B//c) were achieved. In addition, the maximum Fp values of 400 GN/m3 and 120 GN/m3 for B//c were realized at 40 K and 65 K.
In particular, we describe the shape control of nanorods in SmBCO coated conductors by employingusing low temperature growth (LTG) technology using seed layers. From the cross- sectional TEM observations, weit was confirmed that using the LTG technique, the BHO nanorods, which were comparatively thin in diameter and short in length, formed athe fireworks structure in the case of SmBCO coated conductors. The superconducting properties in the magnetic field of the SmBCO- coated conductor on IBAD-MgO with the optimum amount of BHO showed that Fpmax = 1.5 TN / m 3 at 4.2K.
The high-speed growth technique for high performance REBCO coated conductor of the next task is an important subject. In this presentation, we will describe the development of the coated conductor fabricated with a combination a high repetition rate and a novel PLD growth. Thus far we have proposed a vapor-liquid-solid (VLS) method in which a thin liquid layer is interposed in the growing REBCO films with high quality and high speed. A VLS growth technique enables REBCO coated conductor to grow rapidly compared with the conventional PLD method. Furthermore, we will present the results such as introduction of APC for improving not only the fabrication speed but also the performance in the magnetic field of the VLS-RE123 coated conductor on the IBAD tape.

This work was partly supported by a Grant-in-Aid for Scientific Research (15H04252 and 16H04512). A part of this work includes the results supported by the ALCA project of the Japan Science and Technology Agency (JST) and NU-AIST alliance project.