Spray pyrolysis of YBa2Cu3O7-x coated conductors on (100) SrTiO3 substrate

YBa₂Cu₃O_7-x films have been deposited using spray pyrolysis on (100) SrTiO₃ substrate. An extended study on the optimization of the composition, carrying gas flow, deposition temperature as well as annealing time was performed. It was found that these parameters are strongly correlated and affect the morphology, orientation and superconducting properties of the YBCO films. As grown films already exhibit J_c values of 10⁴ A/cm², thus indicating that the correct structure is already formed during deposition. It was found that the temperature gradient in the pyrolysis zone played a fundamental role during the deposition. After modification of this heat gradient by adding a metallic susceptor, a noticeable improvement in the properties of the films was obtained. An in-plane orientation FWHM value of 0.70° was measured from the (102) pole figure. The films exhibited a T_c onset of 91 K (ΔT_c=1.5 K), while the J_c value at 77 K in self-field approached 10⁵ A/cm². Based on an assumed typical intragranular critical current density, we found a 40×40 μm area in our best film where the assumed critical current density is well above 10⁶ A/cm².