Tl-based high-Tc superconducting films prepared by aerosol deposition

Abstract

The deposition of aqueous aerosols of nitrates led to precursor films with a thickness of 3–5 μm. 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 μm. Some aspects of the chemical reactions proceeding during the aerosol deposition and in the thallination step are discussed on the basis of thermogravimetric measurements.