Development of Multipass MOCVD Process for Fabricating (Gd,Y)Ba2Cu3O7-δ Coated Conductors

A multipass metal organic chemical vapor deposition (MOCVD) process has been optimized to fabricate REBa2Cu3O7-δ(REBCO) (RE= Gd+ Y with Gd/Y = 1) thin-film superconducting tapes with high critical currents. Some optimum MOCVD parameters for multipass process are found to be different from those for single-pass process, including RE:Ba:Cu ratio in precursor and deposition temperature. An X-ray diffraction analysis on the effect of changing rare-earth (RE) content on the structural property indicates that an RE-rich composition can improve the in-plane alignment of an REBCO film and favor the multipass process. A 280-m-long REBCO tape made by a three-pass MOCVD process achieved an average critical current of 256.4 A in a 4-mm width with a standard deviation of 9.4 A at 77 K and self-field.