Thin films of Y-Ba-Cu-O on polycrystalline alumina

Polycrystalline alumina is the most widely used ceramic substrate in electronics. By using coevaporation and furnace annealing, the authors have repeatedly obtained thin films of the Y-Ba-Cu-O high temperature superconductor on polycrystalline alumina substrates with a zirconia buffer layer, with positive temperature coefficients of resistance and the highest reported transition temperatures on this substrate of 80 to 83 K. Critical current density was measured as a function of temperature; the value of 1800 A cm -2 at 40 K is similar to that found previously for unoriented polycrystalline films of this superconductor on other substrates.