Structure of metastable Al–Ge phases determined from HOLZ Patterson transforms

Abstract

Abstract The utility of Patterson transforms applied to higher-order Laue zone (HOLZ) reflections in convergent-beam electron diffraction (CBED) patterns from unknown crystal structures is discussed. For HOLZ diffraction from molecular Bloch states located on subsets of atom strings, the transforms contain sharp peaks defining accurate interatomic vectors. As an example, the HOLZ Patterson transforms for two metastable Al–Ge phases are described, where the rhombohedral phase (space group R&3bar;c) is probably isostructural with Zn4Sb3 and a monoclinic phase (space group P21/c) has a new polyanionic structure with tetrahedral coordination of Al by Ge.