Materials Science and Materials Physics in Support of High Temperature Superconducting Coated Conductor Development

摘要

High-temperature superconducting conductors for power application have been identified as a critical enabling technology for future Air Force systems. Work on the materials science and factors limiting current carry capacity of 123 YBCO coated conductor materials are reported. A new model of the high-rate electron-beam coevaporation of 123 YBCO has been developed based on our experiments. It now appears that the process involves an amorphous precursor that is subsequently oxidized. Also the crystallization of the film appears to involve a liquid flux of BaCuOx. The first successful route of synthesis of 248 YBCO thin films has also been developed. We have also carried out scanning tunneling spectroscopy on the surfaces of 2212 BSCCO that reveal the presence of nanoscale inhomogeneities of the superconducting energy gap that could be a source of vortex pinning and hence the critical current in this material. A scanning tunneling potentiometer system has been constructed. This system has yielded the first transport measurements of a complete oxide material on a nanometer scale.