Thin (Hg,Pb)Ba2CaCu3Ox films prepared from thermally evaporated precursors by post annealing in Hg-atmosphere

Superconducting (Hg,Pb)Ba2CaCu2Oy thin films have been prepared in a two step process. Approximatively 0.2 *m thick Ba-Ca-Cu-O or Pb-Ba-Ca-Cu-O precursor films have been deposited on MgO (100) monocrystalline substrates by a sequential evaporation method. Hg was then introduced into the precursor in a closed silica tube. The surface morphology was characterized by SEM, the composition of the superconducting phase was determined by wave dispersive X-ray electron microanalysis. Phase identification was carried out by X-ray diffraction. The c-axis oriented plate-like crystals of the Hg-1212 and (Hg,Pb)-1212 phase were weakly connected. Although coverage of the substrate was uneven, we were able to measure transport superconductivity. The partial substitution of Hg by Pb did not significantly influence the Tc values. For both the Pb-free and Pb-doped Hg-1212 samples Tc(on)-values of about 132 K and the zero resistance temperatures Tc(0) from 105 to 117 K were determined.