The effects of Sm and Y addition on the properties of YBCO thin film prepared by a DCA-MOD method

Off-stoichiometric (Y₁RE_x)Ba₂Cu₃O_{7- δ} (x = 0-0.4, RE = Y or Sm) films have been prepared on LaAlO₃ (1 0 0) single-crystal substrates by a metal-organic deposition using dichloroacetic acid as chelating solution. Coating solutions with excess Sm or Y were prepared by dissolving Y, Sm, Ba and Cu acetates in dichloroacetic acid and distilled water followed by refluxing, drying to obtain blue gel. The final precursor solution for dip coating was prepared by diluting blue gel in 2-methoxyethanol. Coated films were calcined at low temperature up to 500 °C in flowing humid oxygen atmosphere. Conversion heat treatment was performed at 800 °C for 2 h in flowing Ar gas containing 1000 ppm oxygen with a humidity of 9.45%. The viscosities of the precursor solution were increased as the content of added Sm or excess Y increased. The transport critical current density (J_c) of (Y₁RE_x)Ba₂Cu₃O_{7- δ} film was enhanced with the addition of excess Sm and Y up to 20% and then decreased with further addition. Scanning electron microscope (SEM) observation showed that surface roughness was increased with the addition of excess Y.