Metal organic deposition of epitaxial Y123 films using a low-cost vacuum technique

Epitaxial YBa₂Cu₃O₇ (Y123) films were obtained by metal-organic deposition (MOD) using a simple, low-cost vacuum technique without gas flowing. The total pressure and oxygen partial pressure in the furnace were controlled to be 10 kPa and 10 Pa, respectively, by evacuation with a rotary pump followed by refilling with a mixture of O₂ and N₂ (O₂ content: 1000 ppm). XRD analyses exhibited that c-axis-oriented epitaxial Y123 films have successfully been obtained on CeO₂-buffered YSZ (100) (CbZ) and CeO₂-buffered sapphire (012) (CbS) substrates. In-plane alignments of these films were as high as that of the CeO₂ buffer layer. The film on the CbZ demonstrated a high critical current density J_c of ∼2.1 MA/cm² at 77 K all over the film; the fluctuation of J_c being within ±10% of the average. Inductive T_c measurement showed a very sharp peak with T_c=90.5 K. Inductive-J_c and T_c of the Y123 film on CbS were 1.1 MA/cm² and 89.6 K, respectively, whereas the T_c of the Y123 film on LaAlO₃ was lower than 77 K owing to the occurrence of the a-axis grains.