人工ピンニングセンターとしてBaHfO₃ を添加した GdBa₂Cu₃O_y 超伝導線材の引張・圧縮ひずみに対する臨界電流特性

抄録

In order to improve the J_c of REBa₂Cu₃O_y (REBCO: RE = Y, Gd, Er, Nd, Sm)-coated conductors in magnetic fields, it is effective to introduce artificial pinning centers (APCs) into the REBCO films. On the other hand, in superconducting coil applications, bending deformation and hoop stress are added to the REBCO-coated conductors. In this study, we aim to clarify the effect of APC doping on the strain effect in REBCO-coated conductors_. We fabricated pure GdBCO-coated conductors and BHO-doped GdBCO-coated conductors using a pulsed laser deposition method with Nd:YAG reel-to-reel systems on IBAD-MgO substrates. From measurements of the in-field J_c, it was found that BHO doping formed nanorods. The results after measuring the mechanical properties of I_c in the coated conductors, showed an upward convex curve for the I_c strain dependence of of all samples. The peak strain (ε_p) of the pure GdBCO-coated conductors was -0.33%, whereas the ε_p of the 2.2 vol.% BHO-doped GdBCO-coated conductors was -0.68%. There is a correlation in the ε_p and BHO contents. In addition, the strain sensitivity of the I_c in BHO-doped GdBCO-coated conductors is smaller than that of the pure GdBCO-coated conductors. Moreover, regardless of the peak strain, the irreversible strain of the BHO-coated conductors was 0.64%-0.74% for tensile strain.