Preparation and characterization of superconducting Bi-Cd-Sr-Ca-Cu-Oxide thick films

Abstract

Since the discovery of superconductivity in the Bi-Sr-Ca-Cu-O system by Maeda et al. [Jpn. J. Appl. Phys. 27, L209 (1998)], various dopants have been used to try and increase its critical temperature. The partial substitution of Lead (Pb) for Bismuth (Bi) was found to be effective in increasing the volume fraction of the 2223 phase. It was also reported that Lead (Pb) substitution for Bismuth (Bi) stabilizes the high-T_c phase. Hongbao et al. [Solid State Commun 69, 867 (1989)] reported that the partial substitution of Antimony (Sb) for Bismuth (Bi) in the high-Tc phase increases the endpoint critical temperature (T_{c, end}) to 132 K. However, it was found that this phase is so unstable that T_{c, end} decreases to 112 K after thermal cycling between 77 K and room temperature. These results suggest that the doping of foreign elements into the Bi-Sr-Ca-Cu-O system changes the free energy of formation of the high-T_c phase.
In this report, the effects of Cadmium (Cd) doping into the 2223 (high-T_c) phase of the Bi-Sr-Ca-Cu-O system were investigated.