Growth and morphology of quasicrystals

Abstract

The equilibrium shape problem and roughening transition in quasicrystals have been reviewed. Preliminary results on the edge rounding exponent in the binary Al-Mn system indicate a higher value than expected from current theory. It is pointed out that unstable quasicrystalline growth produces faceted dendrites, since growth always occur below the roughening transition temperature. The kinetic mechanism of growth is step controlled. Contrary to the case of growth along periodic potentials, where steps are of the dimension of the lattice parameter, growth of quasicrystals along the quasiperiodic growth directions can have large steps. This is borne out by experiments on the Al-Mn decagonal phase.

Key Words:

• Faceted growth
• quasicrystals
• roughening transition