1. Materials Science and Metallurgy Course C6: Crystallography
Part II
Materials Science and Metallurgy
Course C6: Crystallography
Professor Harry Bhadeshia
Lecture 9: Quasicrystals

2. Quasicrystals
long range order
no 3-D translational symmetry
sharp diffraction patterns

3. Icosahedral
Al-Pd-Mn
Al-Cu-Fe
Ho-Mg-Zn
Decagonal
Al-Ni-Co

4. icosahedron has 12 corners
most definitions indicate 20 faces

7. Al-Ni-Co

12. fiboncci chain

14. Phasons: in quasicrystals, the atomic planes contain more than one shape.
Atoms can fluctuate between two nearby positions in a way that tiles exchange positions without disrupting shape.

15. A quasiperiodic system may be considered as the intersection of a lattice periodic structure in a higher-dimensional space and the physical space.