Growth of highly oriented TlBa2Ca2Cu3O9-y superconducting films on Ag substrates using a dip-coated barium calcium copper oxide sol-gel precursor

Thin films of ba2Ca2Cu3O7, a precursor of TlBa2Ca2Cu3O9-y, were prepared by sol-gel synthesis from an all-alkoxide solution. The barium and calcium precursors were the respective metals reacted with 2-methoxyethanol, and the copper precursor was copper methoxide complexed by triethanolamine. Silver substrates were coated using the sol-gel solution by dip-coating. Subsequent processing included a low-temperature drying step (600 C), repeated coating to provide the desired thickness, heat treatment at 850 C in oxygen to remove carbon, and reaction at 860 C in a two-zone thallination furnace to produce a TlBa2Ca2Cu3O9-y superconducting film. These films were strongly c-axis-aligned, had a zero-resistance temperature (Tc) of 110 K, and a critical-current density (Jc) of 1.9 x 104 A/cm2 at 77 K and zero magnetic field