Synthesis, crystal structure and magnetic properties of a new lithium cobalt metaphosphate, LiCo(PO3)3

A new lithium cobalt metaphosphate, LiCo(PO{sub 3}){sub 3}, is reported for the first time, which was discovered during the exploratory synthesis in Li-Co-P-O system by solid state reaction. The structure has been refined by powder X-ray Rietveld refinement method (P2{sub 1}2{sub 1}2{sub 1}, a = 8.5398(2) A, b = 8.6326(2) A and c = 8.3520(2) A, Z = 4, R {sub p} = 13.6%, R {sub wp} = 19.4%, R {sub exp} = 17.7%, S = 1.11, {chi} {sup 2} = 1.23). It is isostructural with LiM(PO{sub 3}){sub 3} (M = Fe, Cu). It contains (PO{sub 3}){sup 1-} chains with the Co atoms localized in the octahedral sites, bridging four neighboring chains. The magnetic susceptibility measurement showed a typical paramagnetic behavior of high spin of Co{sup 2+}, following the Curie-Weiss law in the temperature range of 5-300 K. Unlike the olivine type lithium cobalt phosphate, LiCoPO{sub 4}, cyclic voltammetry of LiCo(PO{sub 3}){sub 3} assembled in the coin-type cell showed no electrochemical activity in the voltage region of 1-5 V versus Li/Li{sup +}.