Triangular Ge 3 Units in a New Modification of EuGe 3

The hexagonal modification h P8 of the binary compound EuGe 3 was obtained by high‐pressure high‐temperature reaction at 12(1) GPa and 1100(110) K. The compound adopts an Mg 3 Cd‐type crystal structure, forming infinite columnar units of germanium triangles in staggered conformation which are stacked along the [001] direction. X‐ray absorption spectroscopy together with magnetic susceptibility measurements indicate the electron configuration 4 f 7 (2+) of the europium atoms. Chemical bonding analysis reveals covalent bonding within the triangular Ge 3 units and between Eu and Ge. Physical properties measurements indicate bad‐metal type electrical conductivity and an antiferromagnetic ordering of the europium moments below 36(1) K. At 8 GPa and 1000 K, EuGe 3 forms the modification h R36.