Techniques for texturing ceramic superconductors from an amorphous precursor

Amorphous Bi₂Sr₂CaCu₂O₈ (Bi-2212) was crystallized under a uniaxial load of 1500 N at temperatures up to 880°C without Ag and 850°C with Ag to induce texture. Well textured samples (19 mm in diameter and 0.15 mm thick) were obtained for samples heated to within 99% of the melting temperature and quenched for samples with and without Ag. The rate limiting step for formation of the Bi-2212 from the amorphous precursor is a diffusion limited intercalation of (SrCa)CuO₂ into Bi₂Sr₂CuO₆ (Bi-2201) at T>600°C. Samples rapidly heated to within a few degrees of the melting temperature and quenched show 20 to 30% Bi-2201 layers within the Bi-2212 structure. Annealing these samples at 850°C for >60 h eliminates most of the Bi-2201 layers resulting in sharper superconducting transitions and higher intracrystalline critical currents with no adverse effects on grain size or texture. It is more difficult to remove the intercalations in the Ag added material.