Enhancement of Current Carrying Capability in MOD-Processed YBCO Films Using Chemical Doping
Many efforts have been made to improve the current carrying capability of Y<sub>1</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub> (YBCO) films by introducing pinning centers using a variety of techniques. In this study, we have succeeded in producing Y<sub>2</sub>O<sub>3</sub>, BaZrO<sub>3</sub> and Sm doped YBCO films for the development of coated conductors by a metal-organic deposition method using trifluoroacetates (TFA-MOD). Jc exceeding 5 MA /cm<sup>2</sup> at 77 K and self field was obtained in Y<sub>2</sub>O<sub>3</sub> doped YBCO film. Also it was found that YBCO films with Sm substituting for Y have shown an improved critical current density characteristic over a wide range of magnetic fields. A Jc of 0.25 MA/cm<sup>2</sup> at 3 T and 77 K was obtained which is more than 10% of the zero-field Jc. Similar results were obtained in BaZrO<sub>3</sub> doped YBCO films. Additionally, TEM analysis was performed to study the microstructures and the pinning mechanisms. The results indicate that significant enhancement of self-field and in-field Jc of Y<sub>2</sub>O<sub>3</sub>, BaZrO<sub>3</sub> and Sm doped YBCO films may be due to introducing nano-scaled Y<sub>2</sub>O<sub>3</sub> particles, nano-scaled 90deg rotated Y<sub>1/3</sub>Sm<sub>2/3</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub> domains and BaZrO<sub>3</sub> nanodots by different chemical doping, respectively. This indicates that chemical doping is a promising approach for enhancement of current carrying capability of YBCO coated conductors.