Development of Electrically Conductive Buffer for REBCO Conductors

An electrically conductive buffer architecture can enable defect-tolerant RE-Ba-Cu-O (REBCO) superconductor tapes by providing a current shunt path to the substrate. We are developing suitable electrically conductive buffers based on Titanium Nitride (TiN) grown on an ion beam-assisted deposition (IBAD) template on Hastelloy C276 substrate. The aim is to prevent the oxidation of TiN during metal-organic chemical vapor deposition (MOCVD) of REBCO. The buffer architecture was modified to render TiN more oxidation-resistant while maintaining good electrical conductivity. A strong biaxial texture was achieved and a low electrical resistivity of 43 mu ohm cm was measured with this modified buffer architecture. An oxide layer based on the SrTiO3 (STO) cap layer was epitaxially grown using RF magnetron sputtering followed by REBCO film growth by MOCVD. By avoiding oxidation of the modified buffer architecture based on TiN, we achieved a strong epitaxy of REBCO with a sharp texture, without non-00L orientations. Scanning Hall Probe Microscopy (SHPM) data showed uniformly high critical current density throughout the entire REBCO tape.