In-field critical current and pinning mechanisms at 4.2 K of Zr-added REBCO coated conductors

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The critical current and pinning mechanisms at 4.2 K have been studied over a magnetic field range of 0–14 T for Zr-added (0, 5 and 15 mol.%) REBa2Cu3O7-x (REBCO and RE = rare earth) coated conductors fabricated by advanced metal organic chemical vapor deposition (A-MOCVD). It is found that the (Ba + Zr)/Cu content in Zr-added (5 and 15 mol.%) REBCO affects the critical current at 77 K, 0 T as well as density, continuity and shape of BaZrO3 (BZO) self-assembled nanocolumns and RE2O3 in-plane precipitates that significantly enhance the pinning force density Fp(H) as well as isotropic pinning landscape at 4.2 K. In addition to bell-shape dependence of critical current density, Jc, at 4.2 K with (Ba + Zr)/Cu content we observed an unusual Fp(H) behavior correlated to particular type of pinning centers, morphology and distribution that have been revealed by TEM microstructure analysis. By fitting the Dew–Hughes equation of the pinning force density Fp(H) at 4.2 K we extract the scaling behaviors of the Fp(H) associated with the competition of pinning mechanisms driven by vertically-aligned BZO nanorods and in-plane RE2O3 pinning defects. This result sheds light on approaches towards interactive control of strong and isotropic pinning centers in Zr-added REBa2Cu3O7-x (REBCO and RE = rare earth) coated conductors, and especially understanding the correlation between microstructural characteristics and vortex pinning mechanisms at 4.2 K in high magnetic fields.