Abstract: YBCO films doped with Zr or substituted by Gd element were prepared by fluorine-reduced metal organic deposition (MOD) on LAO single crystal. The influences of different dopants on in-field critical current density (J_c) of YBCO films were investigated. It is found that the J_c values of YBCO films in high field were enhanced drastically through substituting Y site by Gd element partially, while the J_c values of YBCO films in low field are not enhanced. The J_c values of YBCO films in low field are improved significantly by adding extra Gd element into YBCO film because of the formation of rare earth oxide particles in YBCO film. But in high field, it has slight effect on J_c values. It is an effective method to improve the property of YBCO film by adding Zr-contained compounds into YBCO film to form BZO nano particles, which can enhance J_c values of YBCO film in low field and in high field. Finally, the high performance Y_0.5Gd_0.5BCO film incorporated with BZO nano particles was prepared. The max pinning force (F_p(max)) is up to 16GN/cm³, as higher as 4 times of that of pure YBCO film. J_c values of Y_0.5Gd_0.5BCO+Zr film at 65K reach 1.31MA/cm²(3T) and 87.7kA/cm²(7T).

Key words: MOD, Gd substitution, Zr dopping, YBCO film