Preparation and characterization of Tl-Ba-Ca-Cu-O 2212 superconducting thick films

Tl2Ba2CaCu2Ogamma superconducting films of high phase purity with thicknesses from 3 to 4 mu m have been prepared on polycrystalline 3 mol% Y2O3-doped ZrO2 substrates. The precursor material was deposited from aerosols prepared by an ultrasonic nebulizer. Thallination was carried by wrapping a Tl-source with the precursor material in a silver foil and annealed at 830 and 815 degrees C. The resistance measurements showed T-c(0)-values of 98 K with transition widths of 6-7 K. The microstructure of the film and the chemical composition of the well-developed crystallites were investigated by scanning electron microscopy in combination with EDX. The superconducting films showed good adhesion to the substrate and preferred c-axis orientation. Isolated particles (0.3-1 mu m) of secondary phases, especially barium-copper-oxides were found at the interface of the superconducting film and the substrate. (C) 1998 Elsevier Science B.V. All rights reserved.