SmBa₂Cu₃O_7-δ coated conductors on the IBAD-MgO substrate fabricated by the Ex-situ conversion process

We investigated the ex-situ conversion process of amorphous precursor films for SmBa₂Cu₃0_7-δ (SmBCO) coated conductors (CC). Amorphous precursor films were first deposited on the LaMn0₃/homoepi MgO/ IBAD-MgO/Y₂0₃/Al ₂0₃/Hastelloy substrate by e-beam co-evaporation and subsequently crystallized to the superconducting phase at various post-annealing temperatures in two different reduced oxygen pressures. In 100 ppm of 0 ₂ in Ar, c-axis oriented SmBCO grains with minor a-axis oriented grains were grown at 825° C whereas polycrystalline SmBCO film with some a-axis oriented grains was formed at 800°C. In the temperature region of 825 ∼ 850°C, protruded spots were observed on the sample surface. In 6 ppm of 0₂ in Ar, SmBCO film composed of a-axis oriented SmBCO grains with partial c-axis oriented grains were obtained at 700° C but other phases were formed above 725° C. The SmBCO sample grown at 700° C exhibited T_c,_zero value of 90.2 K. However, its J_c value at 77 K was negligibly small due to the formation of a-axis oriented grains.