Electron microscopic study of the chimney ladder structures MnSi_2−x and MoGe_2−x

Manganese disilicides MnSi_2−x as well as molybdenum digermanides MoGe_2−x have been studied by electron diffraction and electron microscopy. Both materials, known as Nowotny phases or “chimney ladder” structures, are shown to possess structures based on two in‐commensurable sublattices. Dark field electron microscopy reveals that a strictly commensurable superstructure does not exist. The presence of moiré fringes is related unambiguously to the presence of irrational diffraction spots, forming either orientation anomalies, spacing anomalies or both.