Abstract
Y-Ba-Cu-O (YBCO) superconducting films were prepared on SrTiO3(100) substrates by metalorganic chemical vapor deposition. The precursors used were β-diketone chelates of Y, Ba and Cu. The YBCO films, having superconducting transition temperature defined by zero resistivity (Tc(R=0)) above 90 K and critical current density (Jc) over 106 A/cm2 at 77 K and O T, were obtained at the conditions of oxygen partial pressure (Po2) and deposition temperature (Tdep) near the CuO-Cu2O-O2 equilibrium line (Po2=3.6 Torr-Tdep=850°C and Po2=0.036 Torr-Tdep=700-720°C). The films prepared at these conditions showed Jc over 104 A/cm2 at 77 K in high magnetic fields above 20 T. The nano-composite structure of the YBCO films was studied by transmission electron microscopy. CuO and Y2Cu2O5 grains with a size of 0.1-2 μm were included. The precipitates of about 10 nm in size were observed in the matrix of the YBCO films.
