Symmetry of icosahedral quasicrystals of Cd-Mg-Yb and Cd-Yb has been investigated by the convergent-beam electron diffraction (CBED) method.
The CBED pattern symmetries of the Cd-based quasicrystals are not consistent with any icosahedral point groups, indicating that the structures of the alloys have no icosahedral symmetry. Selected-area electron diffraction patterns of the alloys show regular icosahedral symmetry, indicating that the alloys has a regular icosahedral lattice with a long-range quasiperiodic order. We consider that the structure of the Cd-based quasicrystals is formed by a quasiperiodic arrangement of a non-icosahedral atom-cluster with the same orientation.