High <i>T</i> <i>c</i> screen-printed YBa2Cu3O7−<i>x</i> films: Effect of the substrate material

Abstract

Thick films of YBa2Cu3O7−x have been deposited on highly polished alumina, magnesia spinel, nickel aluminum titanate (Ni-Al-Ti), and barium tetratitanate (Ba-Ti) substrates by the screen printing technique. They were baked at 1000 °C for 15 min, oxygen annealed at a lower temperature, and characterized by electrical resistivity measurements, x-ray diffraction, and optical and scanning electron microscopy. Properties of the films were found to be highly sensitive to the choice of the substrate material. The film on Ba-Ti turned green after firing, due to a reaction with the substrate and were insulating. A film on Ni-Al-Ti had a Tc (onset) ∼95 K and lost 90% of its resistance by ∼75 K. However, even at 4 K it was not fully superconducting, possibly due to a reaction between the film and the substrate and interdiffusion of the reaction products. The film on alumina had Tc (onset) ∼96 K, Tc (zero) ∼66 K, and ΔTc (10–90%) ∼10 K. Our best film was obtained on spinel and had Tc (onset) ∼94 K, zero resistance at 81 K, and a transition width (10–90%) of ∼7 K.