Redetermination of the low-temperature polymorph of Li(2)MnSiO(4) from single-crystal X-ray data

Crystals of dilithium manganese(II) silicate were grown under high-temperature hydro-thermal conditions in the system LiOH-MnO(2)-SiO(2). The title compound crystallizes in the β(II)-Li(3)PO(4) structure type. The coordination polyhedra of all cations are slightly distorted tetra-hedra (m symmetry for MnO(4) and SiO(4)), which are linked by corner-sharing to each other. The vertices of the tetra-hedra point to the same direction perpendicular to the distorted hexa-gonal close-packed (hcp) array of O atoms within which half of the tetra-hedral voids are occupied by cations. In comparison with the previous refinement from powder X-ray data [Dominko et al. (2006 ▶). Electrochem. Commun.8, 217-222], the present reinvestigation from single-crystal X-ray data allows a more precise determination of the distribution of the Li(+) and Mn(2+) cations, giving a perfectly site-ordered structure model for both Li(+) and Mn(2+).