THIN(HG,PB) BA2CACU2OY FILMS PREPARED FROM THERMALLY EVAPORATED PRECURSORS BY POST ANNEALING IN HG-ATMOSPHERE

Superconducting (Hg,Pb)Ba2CaCu2Oy thin films have been prepared in a t wo step process. Approximatively 0.2-mu 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 wa s characterized by SEM, the composition of the superconducting phase w as determined by wave dispersive X-ray electron microanalysis. Phase i dentification was carried out by X-ray diffraction. The c-axis-oriente d plate-like crystals of the Hg-1212 and (Hg,Pb)-1212 phase were weakl y connected. Although coverage of the substrate was uneven, we were ab le to measure transport superconductivity. The partial substitution of Hg by Pb did not significantly influence the T-c values. For both the Pb-free and Pb-doped Hg-1212 samples T-c(on)-values of about 132 K an d the zero resistance temperatures T-c(0) from 105 to 117 K were deter mined. (C) 1998 Elsevier Science B.V. All rights reserved.