INFRARED PROPERTIES OF QUASI-CRYSTALLINE ICOSAHEDRAL AL-MN AND AL-CU-FE PHASES

The infrared properties of icosahedral phases of Al-Mn and Al64Cu22Fe1 4 are studied. In principle, the observed overall spectral shapes of t he optical conductivities of both samples correspond to the low densit y of states at Fermi level and/or to the localization tendency of stat es. The observed anomalies (shoulders and bumps) in the conductivities are discussed in terms of interband transitions and phonons. We obser ved good qualitative agreement between our results and the predictions of the theory of compartmentalization which was suggested to describe the electronic properties of quasicrystals and rational approximants.