Acta Cryst. (2009). E65, i91-i92  [ doi:10.1107/S1600536809048788 ]

The type IV polymorph of KEu(PO₃)₄

A. Oudahmane, M. Daoud, B. Tanouti, D. Avignant and D. Zambon

Abstract: Single crystals of KEu(PO₃)₄, potassium europium(III) polyphosphate, were obtained by solid-state reactions. This monoclinic form is the second polymorph described for this composition and belongs to type IV of long-chain polyphosphates with general formula A^IB^III(PO₃)₄. It is isotypic with its KEr(PO₃)₄ and KDy(PO₃)₄ homologues. The crystal structure is built of infinite helical chains of corner-sharing PO₄ tetrahedra with a repeating unit of eight tetrahedra. These chains are further linked by isolated EuO₈ square antiprisms, forming a three-dimensional framework. The K⁺ ions are located in pseudo-hexagonal channels running along [01] and are surrounded by nine O atoms in a distorted environment.

Online 21 November 2009

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