Two new glaserite-type orthovanadates: Rb2KDy(VO4)2 and Cs1.52K1.48Gd(VO4)2.

The crystal structures of dirubidium potassium dysprosium bis-(vanadate), Rb2KDy(VO4)2, and caesium potassium gadolinium bis-(vanadate), Cs1.52K1.48Gd(VO4)2, were solved from single-crystal X-ray diffraction data. Both compounds, synthesized by the reactive flux method, crystallize in the space group P m1 with the glaserite structure type. VO4 tetra-hedra are linked to DyO6 or GdO6 octa-hedra by common vertices to form sheets stacking along the c axis. The large twelve-coordinate Cs+ or Rb+ cations are sandwiched between these layers in tunnels along the a and b axes, while the K+ cations, surrounded by ten oxygen atoms, are localized in cavities.

[K(2)CsYb(PO(4))(2)]. / K(2)CsYb(PO(4))(2)

The crystal structure of dipotassium caesium ytterbium bis(phosphate) is built up from regular independent PO(4) tetrahedra and YbO(6) octahedra sharing corners and arranged in layers. The structure is, in many respects, similar to that of glaserite.