Related Experiment Video
Updated: Jun 13, 2026

Quantitative Atomic-Site Analysis of Functional Dopants/Point Defects in Crystalline Materials by Electron-Channeling-Enhanced Microanalysis
Published on: May 10, 2021
M3(Au,Ge)19 and M(3.25)(Au,Ge)18 (M = Ca, Yb): distinctive phase separations driven by configurational disorder in
1Department of Chemistry, Iowa State University, Ames, Iowa 50010, USA.
Abstract:
Exploratory syntheses in the M-Au-Ge (M = Ca, Yb) systems have led to the discovery of two cleanly separated non-stoichiometric phases M(3)Au(approximately 14.4)Ge(approximately 4.6) (I) and M(3.25)Au(approximately 12.7)Ge(approximately 5.3) (II). Single crystal X-ray studies reveal that both (space group Im3) feature body-centered-cubic packing of five-shell multiply endohedral clusters that resemble those in the parent YCd(6) (= Y(3)Cd(18)) and are akin to approximate phases in other quasicrystal systems. However, differences resulting from various disorders in these are distinctive. The innermost cluster in the M(3)Au(approximately 14.4)Ge(approximately 4.6) phase (I) remains a disordered tetrahedron, as in the YCd(6) parent. In contrast, its counterpart in the electron-richer M(3.25)Au(approximately 12.7)Ge(approximately 5.3) phase (II) is a "rattling" M atom. The structural differentiations between I and II exhibit strong correlations between lattice parameters, cluster sizes, particular site occupancies, and valence electron counts.
Related Concept Videos
Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Electron Configuration of Multielectron Atoms
Phase Diagrams of Ternary Systems
Ionic Crystal Structures
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Valence Bond Theory
