Experimental and Theoretical Study on the Substitution Patterns in Lithium Germanides: The Case of Li15Ge4 vs Li14ZnGe4

A new ternary lithium zinc germanide, Li13.83Zn1.17(2)Ge4, was synthesized by a high‐temperature solid state reaction of the respective elements. The crystal structure was determined by single‐crystal X‐ray diffraction methods. The new phase crystallizes in the body‐centered cubic space group I4‾ 3d (no. 220) with unit cell parameter of 10.695(1) Å. The crystal structure refinements show that the parent Li15Ge4 structure is stabilized as Li15−xZnxGe4 (x≈1) via random substitution of Li atoms by the one‐electron‐richer atoms of the element Zn, by virtue of which the number of valence electrons increases, leading to a more electronically stable system. The substitution effects in the parent Li15Ge4 structure were investigated through both theory and experiment, which confirm that the Zn atoms in this structure prefer to occupy only one of the two available crystallographic sites for Li. The preferred substitution pattern established from experimental results is supported by DFT electronic structure calculations, which also explore the subtleties of the chemical bonding and the electronic properties of the title compounds. Synthesis of a new Li‐containing compound Li14ZnGe4 was studied. The new phase crystallizes in the same body‐centered cubic space group I43d (no. 220) as the binary Li15Ge4 and represents its substitutional variant. Experimental and theoretical methods both show that one of the two crystallographically unique Li atoms is preferably replaced by the Zn atoms.