Crystal structure of hexagonal phases and its relation to icosahedral quasicrystalline phase in Zn-Mg-RE (RE=Rare Earth) system

摘要

A relationship between hexagonal phases in the Zn-Mg-RE (RE=rare earth) system and icosahedral quasicrystalline phase is discussed.there are three hexagonal phases in the vicinity of Zn_6Mg_3RE_1 which are related with #alpha# lattice parameters by a ratio 3:5:7 but with approximately the same c paameters.A structural modle for the phase with medium a lattice parameter is propose based on the structures of the other two phases recently determined.We also show a preliminary result of X-ray diffraction study of the Zn-Mg-Ho icosahedral phase.