Li4Ge2B as a new derivative of the Mo2B5and Li5Sn2structure types

Abstract

Binary and multicomponent intermetallic compounds based on lithium andp-elements of Groups III–V of the Periodic Table are useful as modern electrode materials in lithium-ion batteries. However, the interactions between the components in the Li–Ge–B ternary system have not been reported. The structure of tetralithium digermanium boride, Li4Ge2B, exhibits a new structure type, in the noncentrosymmetric space groupR3m, in which all the Li, Ge and B atoms occupy sites with 3msymmetry. The title structure is closely related to the Mo2B5and Li5Sn2structure types, which crystallize in the centrosymmetric space groupR\overline{3}m. All the atoms in the title structure are coordinated by rhombic dodecahedra (coordination number = 14), similar to the atoms in related structures. According to electronic structure calculations using the tight-binding–linear muffin-tin orbital–atomic spheres approximation (TB–LMTO–ASA) method, strong covalent Ge—Ge and Ge—B interactions were established.