Electrochemical deposition of superconducting Bi-Sr-Ca-Cu-O films

Abstract

Superconducting BSCCO films were prepared by electrochemical deposition on Ag plate electrodes and post-annealing. Nitrates of Bi, Sr, Ca, and Cu were dissolved in DMSO (dimethyl sulfoxide) in a three-electrode cell with Ag as the working electrode, Au as the counter electrode and Ag/AgCl as the reference electrode. Two electrodeposition techniques were used: dc and pulsed. The as-grown films were subsequently annealed in oxygen-rich environment at 800°C. Scanning electron microscopy revealed rough surfaces with several pinholes for as-grown films, with pulsed-deposited films showing fewer pinholes than dc-deposited ones. Surface quality improved after annealing, with films annealed for longer periods exhibiting fewer pinholes and plate-like grains that are usually associated with a superconducting phase. X-ray diffraction analysis revealed peaks associated with the 2212 and 2223 phases, although a few 2201 peaks were also observed. From resistivity measurements, it was determined that the films had superconducting transition temperatures near 85 K and 110 K, thus confirming the coexistence of the 2212 and 2223 phases of Bi-Sr-Ca-Cu-O.