Physics Department Seminar

Epitaxial YBCO films: processing and performance toward practical applications

Dr. Yifei Zhang
Oak Ridge National Laboratory
Thursday, December 21, 2006
Higgins 235, 4pm

YBCO-based coated conductors, or the second generation HTS wires are being pursued in laboratories and in industry, aiming at large-scale applications of the material. Techniques of fabricating high performance biaxially-textured YBCO films form the core of the technology. While great progress has been made, both fundamental and technical issues remain challenging. The main difficulty is in achieving high critical current, Ic (A/cm-width, for the tape geometry).

In this talk, I will first review highlights of what we have achieved in our lab in recent years. One example is the nanoscale engineering of film structure for enhancing the flux pinning. By doping the source material or implementing substrate surface decoration, nanoscale defects can be introduced that greatly improve the in-field properties. Progress in the BaF2-based ex-situ synthesis technique will be described with emphasis on the effects of low-pressure processing and the modification of the electron-beam co-evaporated precursor for fast conversion. A most recent endeavor in developing an alternative ex-situ technique will also be briefly described.