Ag distribution in thick Bi-2212 floating zone textured rods

Abstract

Bi 2Sr 2CaCu 2O 8+ δ + x wt.% Ag (with x ranging from 0 to 40) powders were prepared by a sol–gel method. These powders were used as precursors to fabricate long textured cylindrical bars through a floating zone melting method (LFZ) induced by a continuous CO 2 laser. On the as-grown textured rods, Ag appears as spherical particles due to its low solubility into the Bi-2212 melt. After annealing, these spherical inclusions change their shape to elongated polygonal ones, which can promote better mechanical properties. This behaviour has been confirmed through flexural essays on the annealed rods. The flexural strength is about 40% higher for samples with low Ag content (<5 wt.%) than for pure Bi-2212. Furthermore, for these Ag contents, superconducting properties are nearly unchanged from the obtained values for optimised Bi-2212 LFZ textured rods. When Ag contents are higher than 5 wt.%, both the mechanical and the superconducting properties decay.