Fabrication of YBa/sub 2/Cu/sub 3/O/sub 7-x/ films on buffered metal tapes fired at low temperature by MOD method using trifluoroacetate salts

Abstract

Metalorganic deposition (MOD) using trifluoroacetates is considered to be one of the most promising methods for coated conductors, because it enables us to obtain very high J/sub c/ films with low-cost facilities. We have optimized various processing conditions in this method and successfully obtained critical current density (J/sub c/) of 4.1 MA/cm/sup 2/ (77 K, 0 T) for the YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) film of 1800 /spl Aring/ in thickness on CeO/sub 2/ buffered YSZ single crystal, which was fired at 800/spl deg/C. In the case of YBCO films on buffered metallic substrates, it is difficult to fabricate under the same deposition condition. Then low temperature heat treatment is required for deposition on metal substrate. On the other hand, such heat treatment also permits non-reacted BaF/sub 2/ in fired film, that leads to low J/sub c/ of the film, Therefore it is the key to fabricate YBCO film with entire reaction of BaF/sub 2/ by the low temperature heat treatment. We have investigated chemical reactions in firing and established a firing profile to fabricate YBCO film even at 725/spl deg/C. With this profile, we can successfully fabricate the YBCO film at 725/spl deg/C on CeO/sub 2/ buffered YSZ single crystal which has J/sub c/ of 3.0 MA/cm/sub 2/ and the YBCO film on CeO/sub 2/ (sputtered)/YSZ (ion-beam-assisted deposition: IBAD) buffered Ni based alloy (hastelloy) tape which has J/sub c/ of 0.81 MA/cm/sup 2/.