Critical Current Properties of GdBa<sub>2</sub>Cu<sub>3</sub>O<i><sub>y</sub></i>-coated Conductors Doped with BaHfO<sub>3</sub> As Artificial Pinning Centers on Tensile and Compressive Strain

In order to improve the Jc of REBa2Cu3Oy (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 Jc, it was found that BHO doping formed nanorods. The results after measuring the mechanical properties of Ic in the coated conductors, showed an upward convex curve for the Ic strain dependence of of all samples. The peak strain (εp) of the pure GdBCO-coated conductors was -0.33%, whereas the εp of the 2.2 vol.% BHO-doped GdBCO-coated conductors was -0.68%. There is a correlation in the εp and BHO contents. In addition, the strain sensitivity of the Ic 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.