Surface-oxidation epitaxy of Ni-clad Ni-20wt%Cr and Ni-clad austenitic stainless steel tapes for Y-Ba-Cu-O coated conductors

We have prepared Ni-clad Ni-20wt%Cr (Ni/NiCr) and Ni-clad austenitic stainless steel (Ni/SS) tapes for YBa/sub 2/Cu/sub 3/O/sub x/ (YBCO) coated conductors with higher strength and lower magnetism than those of pure nickel tape. Highly {100}<001> textured nickel outermost layers on those composite tapes were obtained by cold-rolling and subsequent heat treatment. The surfaces of Ni/NiCr composite tape and Ni/SS composite tape are favorable for epitaxial NiO growth by the surface-oxidation epitaxy (SOE) method. Highly {100}<001> textured NiO layers were formed on those textured composite tapes, as on cube-textured pure nickel tapes. Biaxially textured YBCO films were grown on SOE-NiO layers by the pulsed laser deposition (PLD) method. A thin MgO cap layer deposited on NiO layer improved the surface qualities of NiO, so that the YBCO films with a high critical current density (J/sub c/) of 1.0/spl times/10/sup 5/ A/cm/sup 2/ (77 K, 0 T) have been obtained on SOE-NiO with MgO cap layer on Ni/NiCr composite tape.