Morphology of structures in diffusional growth in three dimensions

Laboratorium für Festkörperphysik, Eidgenössische Technische Hochschule CH-8093 Zürich, Switzerland

Received: 7 May 2001
Accepted: 4 October 2001

Abstract

In our experiments, we investigate in situ three-dimensional crystals during free growth into pure undercooled liquid xenon. The undercooling is in the range of . We initiated morphological transitions of the growing crystal from dendrite to seaweed by a cooling step. The fact that such a transition is possible indicates that a similar morphology diagram, as it is proposed by other authors for two-dimensional growth, is also valid in three dimensions, at least for transient patterns. During the transition from dendrite to seaweed the growth velocity of the crystal decreases and the tip radius increases. For a doublon it is found that the two fingers can be characterized by the tip radius of an unperturbed dendrite at the same nominal undercooling in our experiments, where transient patterns are observed.