Superconductive whisker-like crystal growth in Bi-Sr–Ca-Cu-O and more complicated oxide systems

Abstract

High-quality fibrous crystals have been grown by prolonged heating of amorphous plates in an oxygen flow. The whisker growth rate was varied between 0.005 and 0.1 mm h^–1. The crystals obtained at high temperature had frozen liquid droplets. The body of the whiskers had reasonably constant composition, which did not correspond to the droplet composition. The growth of the fibres occurred by liquid-phase transport of Ca and Cu along the crystal from the amorphous plate to the crystallization zone. This mechanism is termed growth via melt transport under a temperature gradient (MTTG). T_c, J_c and gap parameter, Δ, values for several whiskers were measured. The highest J_c value (2 × 105 A cm^–2 at 77 K) and the highest T_c value were achieved in (2212 + 2223) interlayered fibres.