Structure of the thio-LISICON, Li4GeS4

The structure of high lithium ionic conductors, thio-LISICON (LIthium SuperIonic CONductor), Li4GeS4, was determined by X-ray and neutron Rietveld analysis. Li4GeS4 has orthorhombic space group Pnma with the lattice parameters, a=14.0340(3), b=7.7548(2), c=6.15023(17) Å. The structure is related to the γ-Li3PO4 type and is composed of hexagonal close-packed sulfide ion arrays with germanium ions distributed over the tetrahedral sites which form the framework structure. The Li+ ions in Li4GeS4 are located in both the octahedral and tetrahedral sites. The LiS6 octahedra are connected with each other by sharing edges and form (LiS6)∞ chains along the b-axis. The chain is linked with the adjacent LiS4 tetrahedra, which might form the lithium conduction pathway.