The Co₂Al₉ Structure Type Revisited

Abstract

Abstract The centrosymmetric structure of Co 2 Al 9 (space group P 2 1 / c , Pearson symbol mP 22), the isotypic structures of Rh 2 Al 9 and Ir 2 Al 9 and the slightly distorted acentric structures of Rh 2 Ga 9 and Ir 2 Ga 9 (space group Pc ) were reinvestigated from single crystal X‐ray diffraction data. The structure of Rh 2 Ga 9 represents a new structure type. The difference between the aluminides and the gallides originates in the details of atomic interactions investigated by the electron localization function and band structure calculations.