Chemical vapor deposition of YBa2Cu3O7 using metalorganic chelate precursors

Superconducting films of YBa2 Cu3 O7 were prepared using metalorganic chelate precursors at ambient pressure. Ba and Y were transported using fluoride-substituted β-diketonates, while a β-keto-imide chelate was used for Cu. Deposition at 500 0C on Al2 O3 and SrTiO3 substrates by reaction with O2 saturated with room temperature water vapor formed crystalline mixtures of BaF2 , YF3 , and CuO. Superconducting YBa2 Cu3 O7 formed after annealing in Ar/H2O at 835 0C followed by O2 at 900 and 400 0C with a slow cooling in O2 to below 200 0C. A 2.3 μm film on a (100) SrTiO3 substrate had an onset T/sub c/ of 90 K with zero resistance at 70 K. The film showed a mixture of c- and a-axis orientation. A similar film on (11-bar02) Al2O3 showed zero resistance at 65 K