Metalorganic deposition of high-J c Ba2YCu3O7−x thin films from trifluoroacetate precursors onto (100) SrTiO3

Abstract

Superconducting thin films of Ba₂YCu₃O_7‐x were prepared on (100) SrTiO₃ substrates by metalorganic deposition (MOD) of trifluoroacetate precursors. The best electrical transport properties were measured in films annealed at 750 °C in a humid, low PO₂ gas mixture followed by slow cooling in oxygen. These specimens had sharp resistive transitions with T_c above 90 K and zero‐field critical current densities in excess of 10⁶ A/cm² at 77 K. Critical current densities of this magnitude have not previously been reported in films produced by MOD. The highest J_c obtained in films fired only in humid oxygen was 3×10⁵ A/cm². Annealing at high temperature in the low PO₂ atmosphere also resulted in a smoother surface morphology than was observed in the oxygen‐fired films. Use of the low PO₂ furnace gas appeared to suppress the formation of b‐axis normal oriented grains in the superconducting films and to strengthen c‐axis normal texture. X‐ray powder diffraction indicated the presence of a‐axis normal textured material in the films, although it was not present as separate microstructural features which could be identified by scanning electron microscopy.