On the superconductivity of PbMo 6S 8 and the series M xPbMo 6S 8 and M xPb 1− xMo 6S 8

Abstract

We have studied the correlation between the lattice parameters and the superconducting critical temperature T c in PbMo 6S 8 and the series M x -PbMo 6S 8 and M x Pb 1− x Mo 6S 8 ( M = Cu, Ag, Ba, Sn, Eu, La, Gd, Lu, Y, Th, U). A net correlation was found between the volume V H and T c when M is trivalent or tetravalent. We also found that the high T c modification of PbMo 6S 8 has a maximal occupation of the lattice site centred about the origin of the rhombohedral lattice cell and that this can be obtained by insertion of trivalent and tetravalent elements.