Development of YBa2Cu3O7−x superconducting films on (100) SrTiO3 and (110) Ag substrates by chemical spray pyrolysis

YBa2Cu3O7−x films have been deposited using spray pyrolysis on (100) SrTiO3, (110) Ag single crystals and {110} textured Ag tapes. An extended and systematic study on the optimization of 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. For the Y-123 film deposited on Ag single crystals, the Tc onset was at 90 K and a transport Jc value of around 104 A cm−2 (at 77 K) was observed. On SrTiO3 substrates, an in-plane orientation FWHM value of 0.70° was measured for the (102) pole figure. As-grown films already exhibit Jc values of 104 A cm−2, 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. The films exhibited a Tc onset of 91 K (ΔTc = 1.5 K), while the Jc value at 77 K in self-field approached 105 A cm−2. According to our analysis, we find a 40 × 40 μm area in our best film where the critical current density reaches 5 × 106 A cm−2.