The porosity and its effect on critical current density J(c) of Ag-clad (Bi
,Pb)(2)Sr2Ca2Cu3Ox (Bi-2223) tapes throughout Important steps In their ther
momechanical treatment was investigated by using mass density measurement,
microstructural observation, and superconducting property characterization.
The relative mass density of the final filament for 19 filament tape was l
ess than 75%, even though the J(c) is similar to 50 kA/cm(2) (77K 0T), The
mass density in monofilaments reached 90%, because retrograde densification
during the first heat treatment (HT1) was less or even absent. Well textur
ed Bi-2223 grain growth could result in a significant densification during
the first HT in the monofilament composite. Our results hint at considerabl
e variability in this important property of Bi-2223 tape.