The mixed-valent titanium phosphate, Li2Ti2(PO4)3, dilithium dititanium(III/IV) tris(orthophosphate)

The mixed-valent titanium phosphate, Li2Ti2(PO4)(3), has been prepared by the reactive halide flux method. The title compound is isostructural with Li2TiM(PO4)(3) (M = Fe, Cr) and Li2FeZr(PO4)(3) and has the same (3)(infinity)[Ti-2(PO4)(3)](2) framework as the previously reported Li3-xM2(PO4)(3) phases. The framework is built up from corner-sharing TiO6 octahedra and PO4 tetrahedra, one of which has 2 symmetry. The Li+ ions are located on one crystallographic position and reside in the vacancies of the framework. They are surrounded by four O atoms in a distorted tetrahedral coordination. The classical charge-balance of the title compound can be represented as Li-2(+)(Ti3+/Ti4+)(PO43-)(3).