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

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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.