Preparation of oriented high-Tc Tl-Ca-Ba-Cu-O thin films from co-condensed amorphous Ca-Ba-Cu alloys by post-deposition oxidation and Tl diffusion

Single-phase Tl₂Ca₁Ba₂Cu₂O₈ thin films with zero-resistance transition temperature up to 100 K have been prepared on single-crystal MgO substrates from codeposited Ca-Ba-Cu amorphous metallic alloy precursors. After thermal oxidation of the metallic alloy film, Tl from Tl₂O₃ was vapor deposited and diffused into the resulting mixed metal oxide during a rapid high-temperature anneal. The films prepared in this process are highly oriented with the c axis normal to the substrate.