Pinning Characteristics of Zr, Hf- Added REBCO Coated Conductors Made by Advanced MOCVD in Low-to-High Magnetic Fields

BaMO3 (M = Zr, Hf) pinning centers introduced in REBa2Cu3O7-x (REBCO and RE = rare earth) coated conductors yield superior performance in high magnetic fields. We present the critical current density Jc over a temperature range of 4.2–77 K and magnetic fields of 0–14 T ( B || c- axis), of 5-15 mol.% Zr- and Hf- added REBCO 4+ μm thick film tapes fabricated by advanced metal organic chemical vapor deposition (A-MOCVD). The morphology of self-assembled BMO nanorods aligned along c-axis is found to be dependent on the Zr/Hf content. We also observe a correlation between the density of RE2O3 in-plane nanoprecipitates and the continuity and concentration of BMO nanorods in films of different Ba content. It is found that the (Ba + M)/Cu (M = Zr, Hf) content in REBa2Cu3O7-x affects the shape of pinning force density curves over a wide magnetic field range and temperatures below 20 K. Another remarkable observation is the similarity in the critical current properties of Hf and Zr- added REBCO films as function of (Ba + M)/Cu content at intermediate to high range of (Ba + M)/Cu content. A quantitative analysis of pinning efficiency and correlation with the microstructure of Zr and Hf- added REBCO coated conductors is discussed.