Electronic properties for icosahedral and amorphous phases in the Mg-Zn-Al alloy system

Abstract

Low-temperature specific heat and various electron transport properties have been measured for the icosahedral Mg₃₂Al₁₇Zn₃₂ and six alloys with the formula (Mg_1-xAl_x)₆₅Zn₃₅ (x=0, 0.05, 0.1, 0.15, 0.2 and 0.3), all of which were fabricated in the ribbon form by the melt-spinning technique. This series of Mg-Al-Zn alloys covers the composition range over which the amorphous single phase is gradually taken over by the icosahedral quasicrystalline phase with increasing Al content. The density of states at the Fermi level turns out to be close to the free-electron value for both amorphous and icosahedral phases. As far as the resistivity is concerned, no significant difference is observed between these two phases. However, the Hall coefficient and the thermo-electric power for the icosahedral phase exhibit unique temperature dependences apparently inherent to the quasicrystalline structure and, hence, their behaviour is sharply distinguished from that in the amorphous phase.