Preparation and properties of high-T sub(c) superconducting Tl-1223 thick films obtained by screen-printing method

Tl-based cuprate Tl sub(0.5)Pb sub(0.5)Ba sub(0.4)Sr sub(1.6)Ca sub(2)Cu sub(3)O sub(x) superconducting 20-60 mu m thick films, were obtained using the screen-printing technique with a two-step method comprising deposition of a precursor film on polycrystalline 8 mol% Y sub(2)O sub(3)-doped ZrO sub(2) substrates followed by Tl-vapour annealing at 910 degree C. The resistance measurements yielded T sub(c(0)) values of about 110-115 K with transition widths of 2-4 K. X-ray diffraction confirmed the presence of the superconducting Tl-1223 major phase. Scanning electron microscopy in combination with EDS investigations showed that besides the superconducting crystallites also Ca-Sr-Cu-O compounds of different composition were present as secondary phases. The distribution of the secondary phases and the interaction of superconducting films with YSZ substrates is discussed.