Atomic Self-Diffusion in Quasicrystals: A Molecular Dynamics Study

TL;DR

This study uses molecular dynamics to investigate atomic self-diffusion in dodecagonal quasicrystals, confirming the flip mechanism and highlighting the role of defects and dimensionality in diffusion processes.

Contribution

It demonstrates the occurrence of the quasicrystal-specific flip diffusion mechanism and explores how defects and dimensionality influence atomic diffusion in these structures.

Findings

Flip mechanism confirmed in the system.

Defects catalyze flip diffusion in 3D structures.

Flip diffusion occurs without defects in quasi-2D setups.

Abstract

We present a molecular dynamics study on atomic self-diffusion in Frank-Kasper type dodecagonal quasicrystals. It is found that the quasicrystal-specific flip mechanism for atomic diffusion as predicted by Kalugin and Katz, indeed occurs in this system. However, in order to be effective, this mechanism needs to be catalyzed by other defects such as half-vacancies if the structure is truly three-dimensional. For this reason, flip diffusion is difficult to distinguish from standard vacancy diffusion. In a quasi-two-dimensional setup, however, the flips may occur without other defects. Activation energies and flip frequencies are also determined.