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Abstract

The Y₁Ba₂Cu₃0x superconducting thin films were made by both sequential electron-beam evaporation and co-evaporation of Cu, BaF₂ and Y, followed with high temperature post-deposition annealing. The possibility of making Y₁Ba₂Cu₃0x superconducting film in situ with BaF₂ as the Ba source was investigated by studying the conditions of in situ conversion of BaF₂ to BaO. The BaO concentration in the film as function of the substrate temperature was estimated with an equilibrium thermodynamic model and found to agree with the experimental results. A brief experimental and theoretical exploration of BaCl₂ also showed that BaCl₂ does not have any advantage over BaF2 as the Ba source for in situ growth of Y-Ba-Cu-0 films from the growth temperature point of view.