Electron beam co-evaporation of Y-BaF₂-Cu precursor films for YBa₂Cu₃O7-ycoated conductors

Y-BaF 2 -Cu precursor films for Y-Ba 2 Cu 3 O 7- y (YBCO) coated conductors have been deposited on both uncoated nickel and Rolling Assisted Biaxially Textured Substrate (RABiTS TM ) tapes by electron beam coevaporation. The water partial pressure was kept constant at 1 × 10 -5 Torr during the deposition in order to control the oxygen content in the precursor films. Rutherford backscattering spectroscopy measurements indicate an average composition of Y:Ba:Cu of 1.05:2.10:3.0 with a standard deviation of less than 2.0%. This result was obtained for both moving and stationary tapes. The thickness variation of such precursor films is less than 2.5% over lengths of up to 1 m. Films up to 5 µm thick have been deposited on a stationary tape. An end-to-end J c of 100 000 A cm -2 from a 1 m length of RABiTS TM sample has been obtained with the highest J c of 774 000 A cm -2 in a short section within the tape. The present research demonstrates a possible route for industrial scale-up using electron beam coevaporation of YBCO precursors.