Order and disorder in the modulated phase hp‐Mg9Ge5.1

Abstract

AbstractSingle crystals of Mg9Ge5.1(2) were obtained at a pressure of 5 GPa in the temperature range 723 to 1273 K. The metastable high‐pressure phase exhibits a crystal structure, which may be described as a host‐guest variety of an UCl3‐type framework. The atomic arrangement is characterized by a host crystal structure Mg9Ge3 with disordered germanium guests (≈2 Ge per formula unit) in the channels. The composite arrangement undergoes incommensurate modulation. Upon heating at ambient pressure, the phase transforms into the thermodynamically stable compounds Mg2Ge and Ge at 496(5) K. Measurements of the magnetic susceptibility indicate diamagnetic behavior between 75 and 350 K.