Development of long-length SmBCO coated conductors using a batch-type reactive co-evaporation method

In order to fabricate long-length high temperature superconducting coated conductors, we have employed a batch-type reactive co-evaporation process for the deposition of a SmBCO layer on the IBAD-MgO substrate of LaMnO ₃/epi-MgO/IBAD-MgO/Y₂O₃/Al₂O ₃/Hastelloy. Critical current densities (J_c) of SmBCO coated conductors were investigated with respect to their composition ratios. Higher J_c was obtained in the Sm-rich, Ba-poor and Cu-rich composition region, compared to the stoichiometric region. The highest critical transition temperature (T_c) of the SmBCO coated conductor was ∼94K with a narrower transition width of about 0.5K. A 93m long SmBCO layer was deposited on a 4mm wide IBAD-MgO substrate for 90min. Although some differences in the appearance of pores and Cu oxide precipitates between both ends of the deposited tape exist, the deposited SmBCO layer was dense and biaxially textured. The growth of a highly textured SmBCO layer was maintained up to the thickness of 2.2νm. A minimum I_c of 305A/cm-w was achieved at the 27m section of the 93m long SmBCO coated conductor at 77K in self-field.