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

Abstract
Y-BaF2-Cu precursor films for Y-Ba2Cu3O7-y (YBCO) coated conductors have been deposited on both uncoated nickel and Rolling Assisted Biaxially Textured Substrate (RABiTSTM) 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 Jc of 100 000 A cm-2 from a 1 m length of RABiTSTM sample has been obtained with the highest Jc 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.

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