Intra- and inter-grain critical current density in (Cu,C):1234 superconductors

From DC magnetization studies in fields up to 14 T and temperatures between 20 and 100 K, we estimated the intra- and inter-grain critical current density Jc of (Cu,C):1234 high-Tc superconductors, in the frame of critical state models. The inter-grain Jc was determined by comparing the magnetization loops of as-grown sample and of the ground sample. Finally, short comments on Jc resulted from AC susceptibility measurements and of the impressive increase of intra-grain Jc due to heavy-ion and neutron irradiation are presented