Triangular Ge-3 Units in a New Modification of EuGe3

摘要

The hexagonal modification hP8 of the binary compound EuGe3 was obtained by high-pressure high-temperature reaction at 12(1) GPa and 1100(110) K. The compound adopts an Mg3Cd-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 4f(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, EuGe3 forms the modification hR36.