Mössbauer effect studies of Hume-Rothery stabilization mechanisms in decagonal Al-Fe-Ni quasicrystals

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Abstract
Decagonal quasicrystals of the form Al75Fe25-xNix have been prepared by rapid solidification. These alloys were studied by X-ray diffraction and 57Fe Mössbauer effect methods. The Mössbauer effect spectra show nearly symmetric quadrupole-split doublets. The mean quadrupole splitting shows a monotonie inerease with inereasing Ni content. The mean isomer shift shows a maximum for the composition Al75Fe16Ni9. These Mössbauer effect parameter trends are described in terms of the Hume-Rothery stability criterion. The maximum in the isomer shift corresponds to a minimum in the 57Fes-electron density. This is related to the electron density, yielding a free-electron Fermi sphere with a diameter equal to that of the pseudo-Brillouin zone boundary as determined by X-ray diffraction studies.