THE STUDY OF MICROSTRUCTURE OF BI, PB-SR-CA-CU-O SUPERCONDUCTORS PREPARED BY MULTIPLE INTERMEDIATE PROCESSING

The influence of a multistep intermediate pressing and sintering proce ss on microstructure and the relation between microstructure and value s of critical current density, J(Cr) in Bi, Pb-Sr-Ca-Cu-O high-TC poly crystalline superconductors was studied. The J(C) values increased wit h increasing number of pressing and sintering steps, n, only up to a c ertain value of n. The increase of J(C) was reached by improvement of connections between grains due to compacting and by the alignment of s uperconducting grains in the c-axis direction. The maximal value of J( C) was found for n = 5. The crack development is responsible for decre asing J(C) for a higher number of steps.