Densification effect on the microstructure and critical current density in (Bi,Pb)2Sr2Ca2Cu3O<i>x</i>Ag sheathed tape

Abstract

The density of oxide core in (Bi,Pb)2Sr2Ca2Cu3OxAg sheathed tape was estimated from Vickers hardness and found to be increased to as high as 93% of the theoretical density with increasing the degree of cold working. During heat treatment, this densification before heat treatment promoted the formation of a strong linked microstructure which is characterized by dense microstructure, a high degree of orientation of oxide crystal and smooth interface between the Ag sheath and oxide core. Consequently, we obtained high values of critical current density: 66 000 A/cm2 at 0 T and 14 500 A/cm2 at 1 T for 77 K.