To get high transport capacities in magnetic field with Ag sheathed co
nductors, the Bi2223 phase must be free of residual phases, well-cryst
allized, the lamellas being parallel with the current lines and very d
ense. In a research context on multifilamentary conductor (1), a preli
minary study has been done on bulk material (1 x 4 x 40 mm3 bars) to o
ptimize the frabrication parameters of the multifilamentary tapes. A l
ot of samples, corresponding to the different operating conditions hav
e been electrically characterized and analyzed by EDS so as to get som
e correlations between microstructure and superconducting performances
: determination, concentration and repartition of residual phases, cry
stallinity, orientation and compacity of the Bi2223 phase. We also exa
mined the interactions between the ''refractory phases'', (Ca, Sr)2CuO
3; (Ca, Sr) CuO2; CuO and the liquid phase, Bi2212 enriched with Bi an
d Sr + (Ca, Sr)2PbO4 which promote the recombination into pure and wel
l recristallized Bi2223 phase. Maximum transport current capacities at
77 K-O T were 11 A/mm2 for a commercial powder and 17 A/mm2 (47 A) fo
r a laboratory type powder, the values being around 50 A/mm2 for the c
orresponding multifilamentary conductors.