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

Abstract

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 LaMnO3/epi-MgO/IBAD-MgO/Y2O3/Al2O3/Hastelloy. Critical current densities (J(c)) of SmBCO coated conductors were investigated with respect to their composition ratios. Higher Jc 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 similar to 94 K with a narrower transition width of about 0.5 K. A 93 m long SmBCO layer was deposited on a 4 mm wide IBAD-MgO substrate for 90 min. 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 2.2 mu m. A minimum I(c) of 305 A/cm-w was achieved at the 27 m section of the 93 m long SmBCO coated conductor at 77 K in self-field.