Low temperature phase formation of Tl-based superconducting thin films in reduced oxygen atmosphere

Tl-Ba-Cu-Cu-O superconducting thin films were prepared by magnetron sputtering with postannealing in a reduced oxygen atmosphere. Single-phase Tl/sub 2/Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ can form on the MgO substrate at 800 degrees C under P(O/sub 2/) approximately=0.1 atm. However, the phase formation temperature can be affected by the starting composition of the film. Tl/sub 1/Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ phase can be formed by simply lowering the Tl/sub 2/O pressure. The thermal stability of Tl/sub 1/Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ phase was studied by resistivity measurements at high temperatures.<
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