Al–Pd–Re Icosahedral Quasicrystals and Their Low Electrical Conductivities

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Abstract
In the Al–Pd–Re system, two kinds of icosahedral phases (I-phases) with different quasilattice constants have been found to form at 1173 K. The I-phase with larger quasilattice constant is formed in a wide composition range at 1173 K: 13–25 at.%Pd and 10–15 at.%Re. The conductivity of single-I-phase samples varies greatly with the alloy composition and also from sample to sample for the same nominal composition, and is generally quite low; in some samples of Al70Pd20Re10 it is 0.5 Ω-1cm-1 at 4.2 K, the lowest value ever reported for quasicrystals. The magnetoconductivity at helium temperatures changes systematically with the conductivity value of the sample; it is negative at low temperature with its magnitude decreasing with decreasing conductivity and becomes positive for the lowest conductivity sample. The conductivity behavior cannot be interpreted either in the framework of the weak localization or in that of conventional variable range hopping.