Convergent-Beam Electron Diffraction and Electron Microscope Studies of Decagonal Quasicrystals

概要

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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 P<10>^^^-m2 and centrosymmetric P10_5/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 P<10>^^^-m2. 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 P10_5/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 P<10>^^^-m2 to P10_5/mmc occurs through the mixing of atom clusters with the positive and negative polarities.QuasicrystalDecagonal PhaseConvergent-Beam Electron DiffractionHigh-Resolution Electron Microscope ImageTransmission Electron Microscopy
東北大学の論文
1996-03-28