One of the possible explanations of the major Jc limiting factor at the PbMo6S8 granular superconductor grains surface

The grain surfaces of PbMo6S8, (Pb,Sn)Mo6S8, and SnMo6S8 high magnetic field Chevrel-phase superconductors have been investigated by high-resolution electron microscopy. Our investigations have shown that the grain surface of PbMo6S8 exhibits the presence of MoS2 fringes, whereas the SnMo6S8 powder grain surfaces do not. This gives a simple explanation for the limitation of the critical current densities, J(c), in the very high field PbMo6S8 superconductor. The formation of these MoS2 fringes can now be well understood. Different solutions are then proposed in order to avoid them. (C) 1999 Elsevier Science B.V. All rights reserved.