Research on CeO₂ cap layer for YBCO-coated conductor

Two groups of coated conductor samples with different thicknesses of CeO₂ cap layers deposited by pulsed laser deposition (PLD) under the same conditions have been studied. Of them, one group is of CeO₂ films, which are deposited on stainless steel (SS) tapes coated by IBAD-YSZ (IBAD-YSZ/SS), and the other group is of CeO₂/YSZ/Y₂O ₃ multilayers, which are deposited on NiW substrates by PLD for the fabrication of YBCO-coated conductor through the RABiTS approach. YBCO film is then deposited on the tops of both types of buffer layers by PLD. The effects of the thickness of the CeO₂ film on the texture of the CeO₂ film and the critical current density (J_c) of the YBCO film are analysed. For the case of CeO₂ film on IBAD-YSZ/SS, there appears a self-epitaxy effect with increasing thickness of the CeO₂ film. For CeO₂/YSZ/Y₂O₃/NiW, in which the buffer layers are deposited by PLD, there occurs no self-epitaxy effect, and the optimal thickness of CeO₂ is about 50 nm. The surface morphologies of the two groups of samples are examined by SEM.