Thick films of the T1-based superconductor fabricated via the sol-gel technique

Superconducting thick films of Tl-based cuprate were grown via the sol-gel technique with a two-step method: deposition of a Tl-free precursor film followed by Tl-vapor annealing. A zero resistance superconducting transition temperature (T-c) of 120 K on polycrystalline MgO substrates for Tl-1223 films and of 124 K on (100) LaAlO3 substrates and polycrystalline MgO substrates for Tl-2223 films was obtained. The intragranular critical current density at 5 K of these films is greater than 106 A/cm(2) for Tl-1223 and Tl-2223. The microstructure of these films was examined with X-ray diffraction and scanning electron microscopy. (C) 1997 Elsevier Science B.V.