Syntheses, crystal and electronic structure of a series of quaternary rare-earth sulfides MgRE6Si2S14 (REÂ =Â Y, Ce, Pr, Nd and Sm)

Five quaternary rare-earth sulfide MgRE6Si2S14 (RE = Y, Ce, Pr, Nd and Sm) synthesized by solid-state reactions crystallize in the space group P63, belonging to the MnLa6Si2S14 structure type. Their 3-D structures feature infinite 1-D [(RE6S6)6+]∞ tubular, (SiS4)4- tetrahedron and the imaginary MgMg chain which runs through the [(Y6S6)6+]∞ tubular. The lanthanide contraction phenomenon and the electronic structure calculation are also discussed.