engleski

Extrinsic origin of the insulating behavior of polygrain icosahedral Al-Pd-Re quasicrystals

Polygrain icosahedral i-Al-Pd-Re quasicrystals are known to exhibit dramatically different electronic transport properties to other Al-based quasicrystals. By performing comparative experimental and theoretical studies of the electronic transport and electronic structure of polygrain and monocrystalline i-Al-Pd-Re samples, we show that the extraordinarily high electrical resistivity and the metal-to-insulator transition in the polygrain material are not intrinsic properties of the quasiperiodic lattice, but are of extrinsic origin due to the high porosity and the oxygen-rich weakly insulating regions in the material. We also compare theoretical electronic structures and experimental electrical resistivities of monocrystalline i-Al-Pd-Re and i-Al-Pd-Mn quasicrystals and show that there are no significant differences between these two isomorphous compounds, suggesting that i-Al-Pd-Re is on common ground with other Al-based quasicrystals. We present a structural model of i-Al-Pd-Re.

Al-based quasicrystals; electronic transport properties; variable-range hopping conductivity; porous structure

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