Tl-Based High Tc Superconducting Films Prepared by Aerosol Deposition

The deposition of aqueous aerosols of nitrates led to precursor films with a thickness of 3 - 5 mm. The Ba-Ca-Cu-O and Pb-Sr-Ba-Ca-Cu-O as-deposited layers were calcined at 850 - 870 ?C. Thallination of Ba-Ca-Cu-O precursors at relatively high Tl2O partial pressure resulted in Tl-2212 films with preferred c-axis orientation. Partial substitution of Pb for Tl and of Sr for Ba yielded randomly oriented Tl-1212 films. Deposition of Ba(II)-, Ca(II)- and Cu(II)-bis(2,4-pentanedionates) on polycrystalline silver tapes produced - after subsequent thallination - textured Tl-2223 films with a thickness of about 1 mm. Some aspects of the chemical reactions proceeding during the aerosol deposition and in the thallination step are discussed on the basis of thermogravimetric measurements.