Formation of Bi-Sr-Ca-Cu-O superconducting films by electrodeposition

摘要

Superconducting films of the Bi-SrCa-Cu-O family of oxides were prepared by electrodeposition of the constituent metals followed by an oxidative thermal treatment. The influence of water, stirring of the electrolyte, cleaning of the substrate, and deposition time on the quality of the films were studied. Before the thermal treatment, the electrodeposited films consisted of a mixture of different metals and carbonates of the constituent elements. The oxidation of the metallic phases and the decomposition of the carbonates occurred in the ranges 260-280 deg C and 400-470 deg C, respectively. The final oxides were obtained after an oxidative thermal treatment at 800 deg C. Lower temperatures were not sufficient for the preparation of the superconducting oxide films. The prepared Bi-220l films consisted of a mixture of two phases with different strontium, bismuth, and oxygen contents. The Bi-22l2 films were composed of platelike particles with a preference to orientate along the (00l) direction. These films showed critical temperatures up to 92 K and critical current densities up to 15,000 A/cm~2 (at 77 K and zero field) when the films were pressed before the thermal treatment.