Hybrid Physical-Chemical Vapor Deposition of MgB$_{2}$ Film on Flexible Dielectric and Metallic Substrates

The need for flexible dielectric and metallic substrates arises when considering making wires or tapes for high field applications. To accomplish this, Cu wire and foil with a buffer layer, flexible yttrium stabilized zirconium (YSZ), as well as Nb, Ta, and stainless steel foil were used as substrates for polycrystalline MgB$_{2}$ film growth. The foil substrates used range from 1 to 3 mil thickness. The buffer layers deposited on Cu were Ni plating (on 28 BSG wire) as well as TiB$_{2}$ and Nb deposited by sputtering. These served as a barrier to prevent the chemical reaction between Cu and Mg that occurs during deposition of MbB$_{2}$. The resistance vs. temperature (R-T) dependences were recorded for the films successfully grown on these substrates. For the films on YSZ, R-T was recorded initially and then after bending of the film on the substrate over a diameter of 20mm. The T$_{C}$ of MgB$_{2}$ on stainless steel was 38K; on YSZ and Nb it was 38.5K. This is lower than epitaxial films on SiC substrate with T$_{c}$ up to 41.5K. The R-T curve for MgB$_{2}$ on YSZ remained almost completely unchanged after bending. These films hold promise for electromagnetic field generation applications. This work is supported by NSF and ONR.