Local iron symmetry in quasicrystals
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Iron sites in quasicrystalline Al(TFe)-alloys have been investigated with Mössbauer spectroscopy. The quadrupole splitting of these materials is about 0.4 mm/s, showing that the iron atom is not in an icosahedral\((m\bar 3\bar 5)\) site. A measurement in an external magnetic field ofHext≈5 T yields the asymmetry parameter η=(V xx −V yy )/V zz . The value of η enables one to decide between the applicability of some mathematical structure models of quasicrystals.
The results are:
η=0.8 for decagonal Al7(Mn0.7Fe0.3)2
η=0.9 for icosahedral Al6Cr0.7Fe0.3
using an one site approximation. This means that the iron atoms are in sites with a symmetry lower than axially symmetry, which suits very well for a Penrose lattice.
KeywordsIron Spectroscopy Magnetic Field Thin Film External Magnetic Field
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