Grain Growth, Alignment, and Properties of Bi-based Superconducting Materials.

Hot pressing effect on critical current density (Jc) is studied on Bi2Sr2CaCu2Ox (Bi-2212) superconducting materials. Hot pressing is effective to hasten the grain growth, align the grains, and improve the bulk density of the Bi-2212 materials. In consequence of hot pressing, Jc increases by more than 10 times at 77K under zero magnetic field. Hot pressing effect is enhanced by incorporation of large single crystalline Bi-2212 whiskers. Jc is 3. 1×103 A/cm2, which is about 8 times higher than that for the hot pressed Bi-2212 material without the whiskers, at 77K under zero magnetic field for the Bi-2212 whisker composite. This is due to the haste of grain growth and improvement of grain alignment around the whiskers.