The double-pyramid structure of dendritic ice growing from supercooled water

I. Braslavsky*, S. G. Lipson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

It is known that ice growing freely from supercooled water has a morphological transition at T = - 2.7°C, from a flat dendritic structure at higher temperatures to a twelve-sided double-pyramid structure at lower temperatures. The double-pyramid structure, which can be described as two hollow six-sided pyramids joined at their apices, is built from dendrites growing in well-defined growth directions which are noncrystallographic in the planes normal to the basal plane while their projections on the basal plane retain the hexagonal symmetry. Similar structures have been reported in other hexagonal materials. In order to understand the growth mechanism better, we measured the temperature field in the water around the growing crystals by using the temperature dependence of its refractive index. Since this dependence happens to be zero at the freezing point for regular water (H2O), we use heavy water (D2O), and achieve considerably greater sensitivity. The free growth experiments performed with heavy ice reveal that their morphological behavior is similar to regular ice, as well as their velocities and the angle between the pyramids as a function of supercooling. The temperature measurements showed that the interaction between the two sides of the pyramid via the temperature field is weak. This leads to the conclusion that the solution for the growth mode of the dendrites should be found in the single dendrite level. Explanations of this phenomenon are discussed in the light of recent advances in dendritic growth theory - in particular the concept of microscopic solvability - combined with the behavior of the surface tension and the kinetic effect as a function of crystallographic orientation. It can be shown that growth in a low symmetry direction leads to an asymmetrically growing crystal and to asymmetry in the observed temperature field.

Original languageAmerican English
Pages (from-to)56-61
Number of pages6
JournalJournal of Crystal Growth
Volume198-199
Issue numberPART I
DOIs
StatePublished - 1999
Externally publishedYes

Bibliographical note

Funding Information:
We acknowledge helpful discussions with Ariel G. Notcovich, Netta Cohen, Raz Kupferman, Alon Lev, Jonathan Bar-Sagi, John Wettlaufer and Michael Elbaum. In addition, we want to thank to Shmuel Hoida for technical support. This research was partially supported by the German–Israel Binational Science Foundation (GIF), the Fund for Basic Research of the Israel Academy of Sciences and the Minerva Center for Non-linear Research.

Keywords

  • Dendritic ice
  • Double-pyramid structure
  • Heavy water

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