Structural Relationship between Icosahedral and Frank-Kasper Phases of Al-Li-Cu

摘要

We report on an X-ray diffraction study of the structure of the icosahedral and Frank-Kasper phases of Al5-5Li3-3Cu. It is shown that the two phases have very similar local structure up to about 20 angstroms, while the long-range structure is quite distinct. A detailed analysis of the Frank-Kasper phase suggests that the reported atomic positions and site occupations of this compound are not accurate, and the local structure of this compound is actually closer to that of the quasicrystalline unit cells proposed for the icosahedral phase. The results are consistent with the decorated quasicrystalline lattice model.