Formation of Bi-2212 superconducting whiskers from melt-quenched BSCCO containing alumina

Abstract

Bi–Sr–Ca–Cu–O (BSCCO) superconducting whiskers (2212 phase) were prepared by heating in air the compacted specimens of the mixtures of melt-quenched Bi2SryCa2Cu4Al1Ox powders and alumina powders. Formation of the whiskers depends on the composition and the applied pressure of the compacts. The optimum composition of the melt-quenched products for preparing the long whiskers is Bi2Sr2Ca2Cu4Al1Ox. Superconducting whiskers <1 mm in length (2212 phase) containing an excess amount of copper were grown numerously from the specimen compacted at 20 MPa; long whiskers (2212 phase) of 1–5 mm in length were obtained from that compacted at 180 MPa. These whiskers showed diamagnetic signals below Tc ≃ 80 K.