How do diffraction patterns of amorphous metals differ from those of quasicrystals?

The diffraction patterns of amorphous metals and quasicrystals differ fundamentally due to the presence or absence of long-range order in their atomic structures.

• Amorphous Metals: Because these materials lack long-range coherence in their atomic positions, their diffraction patterns consist only of diffuse rings. They do not exhibit the sharp, discrete features associated with ordered structures.1
• Quasicrystals: These materials possess long-range order, which allows them to produce sharp, discrete diffraction peaks similar to those found in ordinary crystals. However, unlike the patterns of periodic crystals, quasicrystalline diffraction patterns exhibit symmetries—such as fivefold, eightfold, tenfold, or twelvefold rotational symmetry—that are crystallographically forbidden in periodic lattices.12

In summary, while amorphous metals produce diffuse rings, the long-range order in quasicrystals results in distinct, sharp diffraction spots that reveal their unique, non-periodic, yet highly ordered atomic arrangements.1