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Eur. Phys. J. B 7, 85-89
Cubic superspace symmetry and inflation rules in metastable MgAl alloy
L. Elcoro - J.M. Perez-Mato
Departamento de Física de la Materia Condensada, Facultad de Ciencias, Universidad del País
Vasco, Apdo 644, 48080 Bilbao, Spain
wmpelcel@lg.ehu.es
Received: 25 June 1998 / Received in final form and Accepted: 23 September 1998
Abstract
The diffraction properties of a quenched Al-Mg alloy which has been recently termed as a
``cubic quasicrystal" are quantitatively reanalyzed. It is shown that the phase can be interpreted
within the superspace formalism as an ordinary incommensurately modulated structure. The cubic
six-dimensional superspace group that describes its symmetry properties has been determined. The
additional inflation symmetry features exhibited by the diffraction diagram can be summed up by its
invariance for the inflation factor 
, but this property has its origin in the specific value of
the modulus of the modulation wave vectors, which is composition dependent. Other particular
values of this modulus can give rise to similar scaling properties. Further experiments are required
to ellucidate if the mentioned inflation symmetry is a fortuitous situation in a composition
dependent wave vector, or has indeed the physical significance which would allow to describe the
system as a "cubic quasicrystal".
PACS
61.44.Fw Incommensurate crystals -
61.44.-n Semi-periodic solids -
61 Structure of solids and liquids; crystallography
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Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag