Insulator-like electrical transport in structurally ordered Al65Cu20+xRu15−x (x=1.5, 1.0, 0.5, 0.0 and −0.5) icosahedral quasicrystals

Jaiswal, Archna; Rawat, R.; Lalla, N. P.

doi:10.1016/j.jnoncrysol.2004.11.005

Cited by 5 publications

(3 citation statements)

References 36 publications

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“…2,3) Although new approximants 2,4) and a new metastable quasicrystal 5) have been found following this approach, neither insulating nor semiconducting quasicrystals have been realized. The other approach involves aluminum-transition metal (Al-TM) icosahedral quasicrystals, for which semiconductor-like properties 6,7) and metal-insulator-like transitions [8][9][10] have been reported. Signatures for covalence have also been pointed out for both quasicrystals 11,12) and related approximants.…”

Section: Introductionmentioning

confidence: 99%

Semimetallic Band Structure and Cluster-Based Description of a Cubic Quasicrystalline Approximant in the Al–Cu–Ir System

2015

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Density functional calculations were performed for a cubic quasicrystalline approximant in the Al-Cu-Ir system. A semimetallic band structure was developed and analyzed on the basis of Wannier functions constructed from the valence and a part of the conduction band manifold. The Wannier functions were s-and p-like orbitals centered on either the centers of conventional clusters or the icosahedron-like vertices of pseudo-Mackay clusters, and d-like orbitals centered on the transition metals. Grouping the orbitals according to their center, we considered a small cluster for each group of the orbitals. Most of the orbitals contribute to the density of states only within the valence bands, i.e., they are valence states. The exceptions are some of p-like orbitals centered on the icosahedron-like vertices of the pseudo-Mackay clusters, and they contribute to both valence and conduction bands. Each of these p-like orbitals forms a covalent bond with one centered on the neighboring small cluster. The resulting bonding and antibonding orbitals are valence and conduction states, respectively. The number of valence bands (173) of our Al 39 Cu 8 Ir 15 model was then decomposed in terms of the numbers of transition metals (23), clusters (16), and covalent bonds between the clusters (6) as 23 Â 5 þ 16 Â 4 À 6 ¼ 173. The description for the valence-band formation may also be applicable to some of the group 13 element-transition metal intermetallic compounds, such as RuAl 2 .

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Section: Introductionmentioning

confidence: 99%

Semimetallic Band Structure and Cluster-Based Description of a Cubic Quasicrystalline Approximant in the Al–Cu–Ir System

2015

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“…The refined value of electronic diffusivity D for the best fit was found to be $0.6 cm 2 /s and that of s i is in the range of 0.5 · 10 À9 T À2 s/K 2 to 0.5 · 10 À10 T À2 s/K 2 . These are typical values observed for Al-transition metal based stable quasicrystals [2,4,6,7]. Thus the occurrence of these typical values for the refined parameters D and s i indicate that all the refined parameters are physical.…”

Section: Discussionmentioning

confidence: 54%

“…Experiments show that in some cases the conductivity r (=q À1 ) can be expressed by empirical form r(T) = r(0) + Dr(T), where the temperaturedependent part obeys a power-law, Dr(T) / T b , with 1 < b < 1.5, over a wide temperature range [2]. This behavior has been observed in many Al-TM based series of quasicrystalline alloys [4][5][6]. Out of the various Al-TM based icosahedral quasicrystalline alloys, AlPd-Mn alloy series represents a special class where conductivity has been described purely based on quantum interference effects (QIE) [7][8][9][10].…”

Section: Introductionmentioning

confidence: 91%