A Novel Sputtering Technique for Deposition of Robust Buffer Layers Suitable for HTS Technology

The objective of this proposed effort is to identify and develop new and robust buffer layer materials for the recently developed metal-coated YBCO superconducting tape technology. While the current choice of yttria stabilized zirconia (YSZ) and cerium oxide as buffer layers has been appropriate for demonstration of coated tapes with current densities over 106 A/cm2, they may not serve all the required functions and are probably not suitable for production of tapes in long lengths. Hence, we believe, alternate buffer layers with suitable operties will be needed for practical implementation in advanced power sources and power conditioning devices. The phase I effort will involve deposition of biaxially-oriented buffer layers on non-textured Hastelloy substrates using a novel dual magnetron oblique sputtering (DMOS). Suitably thick YBCO layers (up to a micron) will be overgrown on buffer-coated metal tapes using pulsed laser deposition. Material characterization of the coated specimens will be done using SEM, x-ray diffraction (pole figure analysis & phi-scans), and transmission electron microscopy. Magnetic susceptibility measurements will be carried out on the YBCO-coated specimens for testing their current.