Decagonal quasicrystals have been investigated by convergent-beam electron diffraction (CBED) and transmission electron microscopy. The CBED method has revealed that there exist two quasicrystals which belong to the space groups of noncentrosymmetric P10m2 and centrosymmetric P105/mmc. The dark-field microscopy has revealed the existence of inversion domains with an antiphase shift of c/2 at the domain boundaries in the alloys with the space group P10m2. High-resolution electron microscopy has revealed the existence of specific pentagonal atom clusters in all the alloys except Al-Ni-Rh and Al-Ni-Ir alloys. The screw axes in the quasicrystals with the space group of P105/mmc exist at the centers of the clusters in Al-Ni-Rh and Al-Ni-Ir alloys, but exist between the neighbouring two pentagonal atom clusters in the other alloys. A phase transformation from P10m2 to P105/mmc occurs through the mixing of atom clusters with the positive and negative polarities.
|Number of pages||7|
|Journal||Science Reports of the Rerearch Institutes Tohoku University Series A-Physics|
|Publication status||Published - 1996 Mar|
- Convergent-Beam Electron Diffraction
- Decagonal Phase
- High-Resolution Electron Microscope Image
- Transmission Electron Microscopy