Materials, Processing and Quality Control for High Performance Coated High Temperature Superconducting Conductors.

摘要

We explored ways both to enhance J sub c and to optimize/simplify the manufacturing procedures for coated YBa2Cu3Ox (YBCO) conductors. For J sub c-enhancement, we found that the nano-size interface-irregularity through inserting a (Nd1/3Eu1/3Gd1/3) Ba2Cu3Ox sublayer is an effective way to enhance the critical current density (J sub c). Enhancements up to 50% have been observed, especially under high magnetic fields. We also found that the Ca- substituted overlayer on YBCO films with poor crystalline structure can significantly improve the grain misalignment and J sub c. Partial substitution of Y by rare earth elements as previously suggested, however, does not lead to better performance in our synthesis conditions. For manufacturing, copper-metal with electroplated Ni-layer and CeO2-buffer layer has been tested as a cheaper and more convenient alternative for the traditional textured Ni. High crystalline texture has been achieved. The in-plane misalignment angle, delta phi approximately 5-10 deg, is comparable to those on traditional rolling-assisted MOCVD has also been tested in synthesizing both the buffer layer and YBCO films. Reasonable J sub c (77 K) up to 10 exp 6 A/sq cm has been achieved with a very fast process rate.