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

Abstract

Superconducting films of the Bi ¾ Sr ¾ Ca ¾ Cu ¾ 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 ¾ 280 °C and 400 ¾ 470 °C, respectively. The final oxides were obtained after an oxidative thermal treatment of 800 °C. Lower temperatures were not sufficient for the preparation of the superconducting oxide films. The prepared Bi-2201 films consisted of a mixture of two phases with different strontium, bismuth, and oxygen content. The Bi-2212 films were composed of platelike particles with a preference to orientate along the (001) direction. These films showed critical temperatures up to 92 K and critical current densities up to 15,000 A/cm2 (at 77 K and zero field) when the films were pressed before the thermal treatment.