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After the discovery of HTS (High Temperature Superconductor), many types of HTS conductors have been developed. Several BSCCO tapes fabricated by PIT (Powder In Tube) method became commercially available, and the transport current loss characteristics of BSCCO tapes have been investigated by many research groups. The transport current loss characteristics of YBCO tapes, however, are not well studied. This is because measuring transport current requires tape samples over a certain length (15 cm for our own system). Many groups are currently focusing their effort on manufacturing long YBCO tape conductors, and new world records of length and current carrying capability are replacing the old ones in an increasingly fast rate. This paper deals with transport current losses of commercially available BSCCO tapes and YBCO tapes made at Korea Electrotechnology Research Institute (KERI) of Korea. YBCO tapes show relatively high transport current losses. This can be explained by the fact that the YBCO tape does not consist of filaments. Measurement results of the tapes are presented with analyses and discussions.

SrTiO/sub 3/ (STO) films were epitaxially deposited by PLD on textured Ni-3wt%W (Ni-3W) substrates. The STO film was deposited in two steps-reducing atmosphere first, and then oxidizing atmosphere-to prevent the oxidation of the metal surface from hindering the epitaxial relationship between the film and the substrate. The deposited STO films exhibited sharp biaxial texture and dense surface. YBCO films were epitaxially deposited on STO/Ni-3W and showed J/sub c/(77K, self field)=1.2MA/cm/sup 2/ and T/sub c/(onset)=88 K. Auger electron spectrometry depth profile analyses show that the STO film can block the diffusion of the metal from the substrate. This work has shown that STO films epitaxially deposited on textured Ni-3W substrate can be used as a single buffer layer of the high current carrying YBCO coated conductor.

The practical application of HTS materials in power devices requires the HTS conductor which is long, powerful (high current carrying), and affordable. Many different methods for making practical coated conductor include multiple ways of obtaining texture templates and a variety of film deposition methods which include both physical and chemical routes. In this work, three film deposition systems (pulsed laser deposition, sputtering, and evaporation) equipped with reel-to-reel metal tape moving apparatus were installed and used to make meter-long coated conductor. Buffer architecture of CeO/sub 2//YSZ/Y/sub 2/O/sub 3/ was continuously deposited on Ni alloy using sputtering, evaporation, and PLD. YBCO superconducting layer was continuously deposited on buffered metal tape by pulsed laser deposition. End-to-end critical current I/sub c/ of 80 A and critical current density J/sub c/ of 1.3 MA cm/sup -2/ for 600 nm-thick YBCO at 77 K, self-field have been achieved in 1 cm-wide tape over 1 meter length. Longitudinal distribution of the I/sub c/ values was between 72 A/cm and 90 A/cm.