EXAFS study of PbS-SnS solid solution

The local environment of the Pb atom in PbxSn1-xS solid solution was studie d by EXAFS technique. The shortest Pb-S bond length in orthorhombic samples was found to be by approximate to0.2 Angstrom shorter than in cubic PbS. T his indicates that the 6s(2) lone pair of Pb is stereochemically active in the SnS host. Strong correlations found in the distribution of metal atoms in the second shell show that the orthorhombic samples can be considered as solid solutions with unexpectedly strong short-range order. One can expect that the short-range order in PbSnS2 may result in formation of superstruc tures with space groups C-2v(7) or C-2v(2).