LiDy(PO(3))(4).

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 Dy⋯Li distances of 3.54 (1) and 3.48 (1) Å. The DyO(8) dodeca-hedra and LiO(4) tetra-hedra deviate significantly from the ideal geometry. Both Dy and Li occupy special positions (Wyckoff position 4e, site symmetry 2).