The monoclinic form of trilithium dichromium(III) tris(orthophosphate)

Abstract

The monoclinic form of trilithium dichromium(III) tris­(ortho­phosphate), Li3Cr2(PO4)3, was prepared by the reactive halide flux method. The structure of the title compound is composed of a three-dimensional anionic framework with composition ∞ 3[Cr2(PO4)3]3− and Li+ ions situated in the empty channels. The rigid framework built up from CrO6 octa­hedra and PO4 tetra­hedra is the same as that found in other monoclinic Li3 M 2(PO4)3 (M = Fe, Sc, V) phases. The three Li+ cations of Li3Cr2(PO4)3 are unequally disordered over six crystallographically different sites. The classical charge balance of the title compound can be represented as [Li+]3[Cr3+]2[P5+]3[O2−]12. Solid-state UV/Vis spectra indicate that the crystal filed splitting (Δ0) of the Cr3+ ion is around 2.22 eV.