Single crystal structures and magnetic properties of two iron or manganese-lead-antimony sulfides: MPb4Sb6S14 (M: Fe, Mn)

Pure manganese benavidesite (MnPb4Sb6S14) has been synthesized from a solid state reaction of MnS, PbS and Sb2S3 at 600 °C, and its crystal structure determined. Benavidesite is isotypic of natural jamesonite (FePb4Sb6S14), for which a new structure refinement was performed. Both compounds crystallize in the monoclinic symmetry, space group <f>P21/c</f> (No. 14), with unit cell parameters (jamesonite/benavidesite) <f>a=4.0235/4.0216</f>, <f>b=19.074/19.178</f>, <f>c=15.737/15.837</f> A˚ and <f>β=91.89/91.89</f>°, <f>Z=2</f>. The projection of the structure along <f>a</f> shows rods (Pb4Sb6S14)<f>∞</f> parallel to <f>a</f>, connected along <f>c</f> by iron/manganese atoms with octahedral coordination. Octahedra are connected by two opposite edges, forming single chains parallel to <f>a</f>. Magnetic properties have been studied. Jamesonite susceptibility shows an antiferromagnetic behavior below 30 K with an irregularity at about 5 K. Above 30 K, benavidesite and jamesonite have the same behavior but, at low temperature, benavidesite exhibits a paramagnetic behavior. [Copyright &y& Elsevier]