The title compound, potassium yttrium polyphosphate, KY(PO(3))(4), was synthesized using the flux method. The atomic arrangement consists of an infinite long-chain polyphosphate organization. Chains, with a period of four PO(4) tetra-hedra, run along the a-axis direction. Two other polymorphs of this phosphate are known, in space groups P21/n and C2/c.
