YBa₂Cu₃O_7-δ thick films grown on textured metal substrates by liquid-phase epitaxy process

Towards high-current wire application of high-temperature superconductors, YBa₂Cu₃O_7-δ (YBCO) thick films are grown by means of a liquid-phase epitaxy (LPE) process on a (001) surface of NiO single crystal and laser-sputtered NiO buffer layer deposited on a (001) surface of SrTiO₃ single crystal. NiO buffer layers can be rapidly formed on textured Ni tape by the recently developed "Surface-Oxidation-Epitaxy" (SOE) technique which is expected to be a low-cost production method of long metal substrates with highly-textured oxide buffer layer. LPE growth on SOE-buffered textured Ni tapes are also attempted. Moreover, we successfully prepared ∼0.1 m-long LPE-YBCO tapes on {120}<21̄0> Ag-0.1 wt.% Cu alloy tape by using a specially designed LPE furnace equipped with a "reel-to-reel" attachment. BaF₂-added BaO-CuO flux is used in this work, in which the growth temperature of YBCO is drastically lowered from usually used value of ∼1000°C down to 900-930°C. While current transport performances of these LPE-YBCO films are still insufficient for high-current wire application, the present results show the high potential of this LPE process for long-length coated-conductor production.