LiDy(PO3)4

Single crystals of lithium dysprosium polyphosphate, LiDy(PO3)4, were prepared by the flux method. The atomic arrangement is built up by infinite (PO3)n chains extending along the b axis. Dy3+ and Li+ cations alternate in the middle of four such chains, with Dy⋯Li distances of 3.54 (1) and 3.48 (1) Å. The DyO8 dodecahedra and LiO4 tetrahedra deviate significantly from the ideal geometry. Both Dy and Li occupy special positions (Wyckoff position 4e, site symmetry 2).

Single crystals of lithium dysprosium polyphosphate, LiDy(PO 3 ) 4 , were prepared by the flux method. The atomic arrangement is built up by infinite (PO 3 ) n chains extending along the b axis. Dy 3+ and Li + cations alternate in the middle of four such chains, with DyÁ Á ÁLi distances of 3.54 (1) and 3.48 (1) Å . The DyO 8 dodecahedra and LiO 4 tetrahedra deviate significantly from the ideal geometry. Both Dy and Li occupy special positions (Wyckoff position 4e, site symmetry 2).  in the literature of the last three decades due to their possible application as phosphors and laser materials (Yamada et al., 1974;Hashimoto et al., 1991;Horchani et al., 2003).

Related literature
In order to enrich the chemistry of this compound family, we have successfully synthesized single crystals of lithium dysprosium polyphosphate and investigated its crystal structure.
These tetrahedra share common corners yielding infinite chains, of four tetrahedra period, extending along the 2 1 screw axes in the b direction. Four such chains cross the unit cell (Fig. 2).

Experimental
A mixture of Li 2 CO 3 (2 g), Dy 2 O 3 (0.5 g) and H 3 PO 4 (85%, 17 ml), were mixed in a vitreous carbon crucible and preheated progressively to 473 K four 2 h. The temperature was then raised and kept at 600 K for 15 days. Colourless single crystals of LiDy(PO 3 ) 4 were isolated from the reaction mixture by washing with hot water.

Refinement
The distances between dysprosium atoms and the highest peak and the deepest hole are respectively, 1.39 Å and 0.78 Å. Fig. 1. : The asymmetric unit of LiDy(PO 3 ) 4 with anisotropic displacement parameters drawn at the 50% probability level.Symmetry code: (i)-x + 1, y, -z + 1.5.  [Symmetry codes: (i)-x + 1, y, -z + 1.5; (ii)-x + 1, -y + 1, -z + 2; (iii)x, -y + 1, z -1/2; (iv)x, y + 1, z; (v)-x + 1, y + 1, -z + 1.5.   Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.