Sinter-forging conditions, texture and transport properties of Bi-2212 superconductors

The optimization of the sinter-forging process of the Bi-Sr-Ca-Cu-O (2212) superconducting ceramic, synthesized by a polymer matrix method has been do ne. The precursor powder was pressed under uniaxial stresses ranging betwee n 15.9 and 46.8 MPa, and heated between 830 degreesC and 845 degreesC. Rath er well textured samples showing less than 5.6 disorientation degrees for 5 0% of the grain respect to the ab plane have been obtained. The relationshi ps between the stress value as well as the sinter-forging temperature and t he samples texture have been correlated with the critical current densities , J(c), at 77 K. Maximum J(c) close to 700 A cm(-2) have been achieved with a pressure of 31.4 MPa and a temperature of 840 degreesC showing that anne aling under O-2/N-2 has also to be optimized to obtain in such sinter-forge d bulk materials higher J(c) values. (C) 2000 Elsevier Science B.V. All rig hts reserved.