Dopant Effects on the Superconductivity in the Bi-Sr-Ca-Cu-O System

Abstract

The effects of 34 different dopants on the BiSrCaCu 2 O y ceramics were investigated. The dopants can be classified into four categories depending on their solubilities and substitutional properties in the Bi-Sr-Ca-Cu-O structure. Dopants in the first group, i.e. Fe, Co, Ni and Zn, dissolve and substitute into the copper site and can significantly reduce the transition temperatures ( T c 's) of the high- and low- T c phases. The second group of dopants, i.e. rare-earth elements, substitute into the Ca sites and cause the disappearance of the high- T c phase and increase the T c 's in the low- T c phase. The dopants in the third group, i.e. alkaline metals and phosphorus, have a strong tendency to decompose the superconducting phase. The remainder of the dopants investigated were classified as the fourth group. Superconductivity of the high- and low- T c phase of the fourth group remains almost uneffected.