Lithium cobalt(II) pyrophosphate, Li 1.86CoP 2O 7, from synchrotron X-ray powder data

Abstract

Structure refinement of high-resolution X-ray powder diffraction data of the title compound gave the composition Li 1.865CoP 2O 7, which is also verified by the ICP measurement. Two Co sites exist in the structure: one is a CoO 5 square pyramid and the other is a CoO 6 octa-hedron. They share edges and are further inter-connected through P 2O 7 groups, forming a three-dimensional framework, which exhibits different kinds of inter-secting tunnels containing Li cations and could be of great inter-est in Li ion battery chemistry. The structure also exhibits cation disorder with 13.5% Co residing at the lithium (Li1) site. Co seems to have an average oxidation state of 2.135, as obtained from the strutural stochiometry that closely supports the magnetic susceptibility findings.