Microstructure Characteristics of High Lift Factor MOCVD REBCO Coated Conductors With High Zr Content

We report the microstructural characteristics of high levels of Zr-added REBa
₂
Cu
₃
O
_7-x
(RE = Gd, Y rare earth) coated conductors fabricated by Metal Organic Chemical Vapor Deposition (MOCVD). The enhancements of the lift factor defined as a ratio of the in-field (3 T, B ∥ c-axis) critical current density (J
_c
) at 30 K and self-field J
_c
at 77 K have been achieved for Zr addition levels of 20 and 25 mol% via optimization of deposition parameters. The presence of strong flux pinning is attributed to the aligned nanocolumns of BaZrO
₃
and nanoprecipitates embedded in REBa
₂
Cu
₃
O
_7-x
matrix with good crystal quality. A high density of BZO nanorods with a typical size 6-8 nm and spacing of 20 nm has been observed. Moreover, the high Zr content was found to induce a high density of intrinsic defects, including stacking faults and dislocations. The correlation between in-field performance along the c-axis and microstructure of (Gd,Y)BCO film with a high level of Zr addition is discussed.