RE ₇ M ₄ InGe ₁₂ (RE = Y, Gd–Er; <i>M</i> = Rh, Os) Quaternary Germanide Series Expansion with Structural Motif Clustering

Intermetallic compounds with two alternating planes of atoms, forming <i>AB</i> layer stacking, are found in numerous prototypes. Yb₇Co₄InGe₁₂ type (adopting tetragonal <i>P</i>4<i>/m</i> space group) belongs to this group, and in this work, we vastly expanded this series by synthesizing compounds with the <i>RE</i>₇M₄InGe₁₂ (<i>RE</i> = Y, Gd, Tb, Dy, Ho, Er; <i>M</i> = Rh, Os) formula by arc melting. Structural analysis and impurity identification by X-ray diffraction and compositional analysis with energy-dispersive X-ray spectroscopy confirm the Yb₇Co₄InGe₁₂-type structure and composition. The anionic network (<i>M</i>-In-Ge) motif geometry and stability are influenced by lanthanoid contraction <i>via RE</i> element substitution. Density functional theory calculations reveal that <i>M</i> substitution, particularly from Ru to Os, Rh, and Pd, shifts the Fermi level, <i>E</i>_<i>F</i>, with electronic structure stabilization occurring with the valence electron-rich metals. These results support previous knowledge of the Yb₇Co₄InGe₁₂ structure type and offer more insight into the tunability of electronic properties in <i>RE</i>₇M₄InGe₁₂ through element substitution. Finally, the structural evolution of Yb₇Co₄InGe₁₂ type among other intermetallic prototypes with similar structural motifs was analyzed using materials informatics tools for crystal structure clustering, which could be expanded to other structural families.