Iron atomic jumps in Al–Cu–Fe quasicrystals and approximants

Abstract

Abstract The iron dynamics in the icosahedral quasicrystal i-AlCuFe and two cubic 1/1 approximants as well as the non-approximant cubic B2 phase has been studied by Mössbauer spectroscopy. In the i-phase the iron Lamb-Mössbauer recoilless fraction decreases below that predicted for lattice vibrations alone above about 550 K. This decrease is correlated with the onset of a quasielastic signal at high Doppler velocities, demonstrating local iron jump processes at temperatures above this point. In the two cubic approximants, a loss in the recoilless fraction also occurs above 550 K, revealing the same kind of Fe dynamics as in the i-phase but the effect is smaller. On the other hand, no anomalous Fe dynamics (other than lattice vibrations) is detected in the B2-AlCuFe phase. A comparison is made to literature Mössbauer and neutron scattering results in i-AlCuFe.