Meisterernst, Goetz; Bauer, Birgitta; Gille, Peter
AlCoNi quasicrystal sphere growth experiment from a metallic solution.
In: Zeitschrift fur Kristallographie, Vol. 224, Nr. 10: S. 471-477
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Crystal growth studies starting from spherical surfaces of singlecrystals can reveal morphological features that cannot be obtained inusual growth experiments. Especially, facets of a greater variety ofcrystallographic forms may occur that are otherwise hidden by theslowest growing faces which dominate the crystal’s morphology. We did asphere growth experiment with a decagonal Al(72)Co(9)Ni(19) quasicrystalprepared from a large single-grain sample formerly grown using theCzochralski method from an off-stoichiometric melt. By heating thepolished crystalline half-sphere to a temperature slightly higher thanits own growth temperature a thin liquid layer of self-flux formed. Apartial evaporation of Al being the solvent of this system causedre-crystallisation at the surface of the quasicrystalline sphere. Afterseveral times repeating this process at further increasing temperatures,tiny faces of four different crystallographic forms developed. By usingan optical goniometer and electron scanning microscopy indexing of thesefacets was possible. With the only exception of the decagonal prism5100006 they had not been observed so far in contact to the melt. Theresults are discussed with respect to the inclined net plane conceptestablished by Steurer and Cervellino [Acta Cryst. A57 (2001)333-340]. The experimental approach is not specific to sphere growthstudies of quasicrystals but can be applied to other high-temperaturesolution growth systems as well.