Coated conductors on Cu70Ni30 textured tape: The potential of a single conductive buffer

Single buffer architecture has been explored for coated conductor (CC) applications. Conductive La or Nb doped - SrTiO3 (La:STO and Nb:STO) buffers have been epitaxially grown on Cu70Ni30 substrates by Pulsed Laser Deposition (PLD). The influence of substrate properties on texture development was investigated. The optimisation of deposition parameters and compatibility of the buffer layers with YBCO are reported. An attempt is made to find a correlation between the surface grain size of the buffer and the properties of the superconductors. Results of the same architecture deposited on rf magnetron sputtered TiN/NiCrW samples are presented for comparison. The issue of a conductive buffer stabilisation of CC against thermal breakdown is discussed. Property characterisation by X-ray Diffraction revealed excellent bi-axial alignment of the YBCO layers with out-of-plane and in-plane best FWHM values of 4o and 9o respectively. The surface morphology was explored by AFM and SEM. The superconducting parameters have been measured by standard fourprobe technique and DC SQUID magnetometry.