PREPARATION OF (TL,BI) (BA-0.4,SR-1.6)CA2CU3O9 THICK-FILMS EPITAXIALLY GROWN ON LAALO3(100) SUBSTRATES BY A SOL-GEL PROCESS

We report on the preparation of 5 mu m thick (Tl,Bi)(Ba-0.4,Sr-1.6)Ca2 Cu3O9 ((Tl,Bi)-1223) high T-c films by a modified sol-gel (Pechini) pr ocess. The process was performed by the preparation of a gel containin g the metallic atoms, the coating of the substrates with the gel, the pyrolisis of the gel, and a post annealing process, without an additio nal thallium oxide vapour source. X-ray diffraction patterns (theta - 2 theta scans) showed that the thick films prepared on LaAlO3(100) sub strates consisted mainly of the (Tl,Bi)-1223 phase, with high c axis o rientation, and phi scans revealed epitaxial film growth. EDX measurem ents showed a composition ist good agreement with the (Tl,Bi)-1223 pha se. Superconductivity was reached with T-c valves up to 102 K.