Critical currents in (Bi,Pb)2Sr2Ca2Cu3Ox powder

We have performed magnetic measurements of the critical current density ( J c ) in powders of the (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O x material. Considering flux relaxation, and applying the same criteria used for resistive J c measurements, we arrive at J c ≈2×10 4 A / cm 2 (77 K, 0 T). This value is considerably less than the highest values obtained in silver sheathed tapes of the same material, indicating that deformation induced flux pinning and possibly even grain boundary pinning may play some role in determining the J c in tapes.