Sodium terbium(III) polyphosphate

Abstract

Single crystals of the title compound, NaTb(PO3)4, were obtained by solid-state reaction. This compound belongs to type II of long-chain polyphosphates with the general formula A I B III(PO3)4. It is isotypic with the NaNd(PO3)4 and NaEr(PO3)4 homologues. The crystal structure is built up of infinite crenelated chains of corner-sharing PO4 tetra­hedra with a repeating unit of four tetra­hedra. These chains, extending parallel to [100], are linked by isolated TbO8 square anti­prisms, forming a three-dimensional framework. The Na+ ions are located in channels running along [010] and are surrounded by six oxygen atoms in a distorted octa­hedral environment within a cut-off distance <2.9 Å.

Local Environment of Terbium(III) Ions in Layered Nanocrystalline Zirconium(IV) Phosphonate–Phosphate Ion Exchange Materials

“…Despite most of the structures having similar Tb–O and Tb–P distances, many still performed very poorly during refinement, not fitting well to the intermediate-range structure. The four best refinements came from the following structures: (a) potassium terbium tetrakis (phosphate­(V)), (b) sodium terbium polytetraphosphate, (c) potassium terbium diphosphate­(V) dihydrate, and (d) Scheelite-type terbium phosphate . The fits are displayed in Figure .…”