Eur. Phys. J. B 29, 51-59 (2002)
https://doi.org/10.1140/epjb/e2002-00261-3

The Al-Pd-Mn quasicrystalline approximant ξ'-phase revisited

¹ Laboratoire Léon Brillouin (CEA-CNRS), CEA Saclay, 91191 Gif-sur-Yvette cedex, France
² Laboratoire d'Étude des Microstructures (ONERA-CNRS), BP 72, 92320 Châtillon Cedex, France
³ Laboratoire de Physique des Solides ((UMR 8502)) , bâtiment 510, Université Paris-Sud, 91405 Orsay Cedex, France

Corresponding author: ^a denoyer@lps.u-psud.fr

Received: 11 April 2002
Revised: 24 June 2002
Published online: 17 September 2002

Abstract

A detailed investigation of the Fourier space of several Al-Pd-Mn samples with composition Al-72.6 at. %, Pd-22.9 at. %, Mn-4.5 at. % is reported. In the phase diagram of the Al-Pd-Mn ternary alloy, this composition corresponds to the so-called ξ' phase which was described as an icosahedral quasicrystalline approximant. By re-examining the Fourier space by means of X-ray diffraction (powder patterns and single crystal precession patterns), complex structures in close relation with the ξ'-phase have been observed. These long-range order complex structures are described as resulting from a periodic perturbation of the ξ' structure along the c direction. Two states with periodicities and have been observed in this study (τ: golden mean). Structural models based on periodic arrangements of “defects” layers separating layers of phase are proposed. These two states are certainly intermediate states between the  phase and the metastable decagonal quasicrystalline phase.