Synthesis and crystal structure of two new oxychalcogenides: Eu5V3S6O7 and La10Se14O

The crystal structure determination of two new oxychalcogenides, namely Eu5V3S6O7 and La10Se14O, is reported. Eu5V3S6O7 crystallizes in the orthorhombic symmetry (space group Pmmn) with unit cell parameters (in Å): a=17.463(2), b=3.6732(4), and c=10.007(1). This compound is isotypic with the Ln5V3S6O7 compounds (Ln=La–Nd), and its structure has been refined to R1=0.0248. Eu atoms, which are nine-coordinated by O and S atoms, are associated to form ribbons that are interconnected by [VS4O2] octahedrons. La10Se14O crystallizes in the tetragonal symmetry (space group I41/acd) with unit cell parameters (in Å): a=15.926(2), and c=21.061(5). The structure was refined to R1=0.0347. La10Se14O is isostructural with the Pr10X14O compounds (X=S and Se). The only structure difference is observed for one La site that is found split, in connection with a mixed O/Se site filling.