Development of HTS Buffer Layers Using the ECONO Process

Under Phase I effort, Applied Thin Films, Inc. (ATFI) discovered a new process to deposit oxide buffer layers for HTS coated conductors that is economical, scalable, and has demonstrated excellent performance with YBCO films (current densities of 1MA/cm2). The process is called ECONO (Epitaxial Conversion to Oxide via Nitride Oxidation) which is now being considered as the primary contender for the production of buffer layers suitable for the next generation HTS wires. A leading manufacturer ofHTS products has obtained a non-exclusive license on the ECONO process from ATFI and will work closely in the proposed Phase II effort. The process involves depositing a high quality yttrium zirconium nitride film which is subsequently converted to yttriastabilized zirconia (YSZ) via a simple oxidation step yielding a high quality epitaxial film. The main benefit is that it eliminates the need for a seed layer which is difficult and expensive to implement. In Phase II, ATFI will further develop the ECONOprocess and demonstrate production of YSZ buffer layers in long lengths through continuous processing on non-magnetic textured substrate tapes. The technical effort will include optimization of chemistry and the conversion process, increasing depositionrate, improving microstructural and epitaxial quality.