Synthesis, structure, and magnetic properties of the quaternary oxysulfides Ln${}_5$V${}_3$O${}_7$S${}_6$ (Ln = La, Ce)

Two rare earth oxysulfides Ln${}_5$V${}_3$O${}_7$S${}_6$ (Ln = La, Ce) have been synthesized and their structures determined. The two isostructural compounds crystallize in the orthorhombic space group Pmmn (no. 59). The structure features one-dimensional edge-sharing VS${}_4$O${}_2$ octahedron chains parallel to the b axis. The bonding between V and S/O is covalent, and between Ln${}^{3+}$ and the rest of the matrix ionic. Magnetic susceptibility measurement revealed that V is in a mixed valence state of V${}^{3+}$ and V${}^{4+}$. Its magnetic behavior follows the Curie-Weiss law.