Preparation of superconducting Tl-Ca-Ba-Cu thin films by chemical deposition

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Abstract
A chemical deposition process for the preparation of superconducting thin films of Tl2CaBa2Cu2O8 (2122) and Tl2Ca2Ba2Cu3O10 (2223) has been developed. Oriented, superconducting 2122 and 2223 thin films have been successfully fabricated on single-crystal yttria-stabilized zirconia and magnesium oxide substrates (〈100〉 orientation). Epitaxial films have been prepared on magnesium oxide. Chemical analysis of the film composition by energy dispersive x-ray analysis is in agreement (2122 vs 2223) with the phases indicated by powder x-ray diffraction. The thin films of these compounds exhibited superconducting transition temperatures above 105 K as determined by variable-temperature resistivity and ac magnetic susceptibility measurements. In addition, microwave surface resistance measurements at 150 GHz show that these films have very low losses at 77 K (1 mΩ).