Covalent bonds and their crucial effects on pseudogap formation in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi><mml:mo>−</mml:mo><mml:mi mathvariant="normal">Al</mml:mi><mml:mo>(</mml:mo><mml:mi mathvariant="normal">M</mml:mi><mml:mi mathvariant="normal">n</mml:mi><mml:mo>,</mml:mo><mml:mi mathvariant="normal">R</mml:mi><mml:mi mathvariant="normal">e</mml:mi><mml:mo>)</mml:mo><mml:mi mathvariant="normal">Si</mml:mi></mml:math>icosahedral quasicrystalline appro

Kirihara, Kazuhiro; Nagata, Tomohiro; Kimura, Kaoru; Kato, Kenichi; Takata, Masaki; Nishibori, Eiji; Sakata, Makoto

doi:10.1103/physrevb.68.014205

Cited by 61 publications

(51 citation statements)

References 40 publications

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“…45,47 This behavior is likely to be related to the peculiar nature of critical electronic states close to the Fermi level. 3,48,49 Accordingly, the narrowing of the ␥ 1 parameter in the refined model can be interpreted as higher localization of electronic states induced by an enhancement in the covalent bonding nature in the cluster network, 50 in agreement with photoconductivity measurements. 51 Note that optimizing 1 is a necessary but not sufficient condition to attain the optimal ZT value characterized by A 1 = A 3 in Eq.…”

Section: Electronic Structure Refinementsupporting

confidence: 66%

Optimizing the thermoelectric efficiency of icosahedral quasicrystals and related complex alloys

Maciá

2009

Phys. Rev. B

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In this work we analyze the potential role of quasicrystals and related alloys in thermoelectric material research. Relatively large figure of merit values are expected for those samples exhibiting two properly located narrow features in the density of states close to the Fermi level. It is expected that optimized quasicrystals will perform better at relatively low temperatures, whereas the ZT curve of complex metallic alloys reaches its maximum at high temperatures. Among state-of-the-art quasicrystals most promising samples for thermoelectric applications are found in the AlPd͑Mn,Re͒ system. Quasicrystalline and related approximants in the ScMgCuGa and CaAuIn systems, synthesized on the basis of pseudogap tuning concepts, appear as promising candidates as well.

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Section: Electronic Structure Refinementsupporting

confidence: 66%

Optimizing the thermoelectric efficiency of icosahedral quasicrystals and related complex alloys

Maciá

2009

Phys. Rev. B

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“…We have pointed out that not only the composition dependence but also the difference in the electrical properties between different alloy systems is related to the difference in the bonding nature of local atomic arrangements such as icosahedral clusters. In 1/1-Al(Mn, Re)Si approximant crystals, which possess icosahedral symmetric clusters called Mackay icosahedral (MI) clusters and exhibit quasicrystal-like electrical properties, the bond strength distributes widely from weak metallic to strong covalent bonds, and the intracluster bonds are stronger than the intercluster bonds [3,4]. Al-based icosahedral quasicrystals have same structure unit, i.e., MI cluster.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric properties of Al–Pd–Re quasicrystal sintered by Spark Plasma Sintering (SPS): effect of improvement of microstructure

Takagiwa¹,

Kamimura²,

Hosoi³

et al. 2009

Zeitschrift Für Kristallographie - Crystalline Materials

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Quasicrystals / Thermoelectric properties / Microstructure / Spark Plasma Sintering (SPS) / Al--Pd--Re Abstract. We report the thermoelectric properties of poly-grain Al--Pd--Re icosahedral quasicrystals and discuss an effect of improvement of their microstructure. The improvement of microstructure by using Spark Plasma Sintering (SPS) method resulted into a large increase of the electrical conductivity but less increase of the thermal conductivity. The relative density dramatically increased up to more than 90% by SPS. On the other hand, the microstructure itself does not have critical influence on the Seebeck coefficient, which is found to be strongly correlated with e=a (sample's compositions). Consequently, the dimensionless figure of merit (ZT) increased three times from 0.05 to 0.15.

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“…We have pointed out that not only the composition dependence but also the difference in the electrical properties between different alloy systems is related to the difference in the bonding nature of local atomic arrangements such as icosahedral clusters. In 1/1-Al(Mn, Re)Si cubic approximant crystals, which possess icosahedral symmetric clusters called Mackay icosahedral (MI) clusters and exhibit quasicrystal-like electrical properties, the bond strength is distributed widely from weak metallic to strong covalent bonds, and the intracluster bonds are stronger than the intercluster bond [3,4]. Both s and S are rather large because the quasicrystals are basically metallic alloys and have semiconductor-like properties.…”

Section: Introductionmentioning

confidence: 99%

“…It has been suggested that m* and the ZT can be increased by strengthening the intracluster bonds and weakening the intercluster bonds. From the results of MEM/Rietveld analysis of 1/1-Al(Mn, Re)Si cubic approximant crystals [3,4], the covalent bonding nature in the 1/1-AlReSi is stronger than that in the 1/1-AlMnSi approximant crystal. It seems effective to substitution of intercluster Re sites in i-Al--Pd--Re quasicrystal with a lighter transition metal element in order to decrease the intercluster bond strength.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric performance of Al–Pd–Mn quasicrystals: comparison with (1/1, 2/1-)AlPdMnSi approximants and improvement by Ga substitution for Al

Takagiwa¹,

Kamimura²,

Hosoi³

et al. 2009

Zeitschrift Für Kristallographie - Crystalline Materials

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Abstract. We report the thermoelectric properties of polygrain icosahedral Al--Pd--Mn quasicrystal and compare with those of (1/1, 2/1-)AlPdMnSi approximant crystals. To improve the dimensionless figure of merit (ZT), we substitute Ga for Al atoms in Al--Pd--Mn quasicrystal in accordance with the guiding principle of "weakly bonded rigid heavy clusters" (WBRHCs). Although the thermoelectric properties do not obey the WBRHCs principle, the maximum ZT increased by a factor of 1.4 from 0.18 for Al 71 Pd 20 Mn 9 to 0.26 for Al 68 Ga 3 Pd 20 Mn 9 quasicrystal.

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Covalent bonds and their crucial effects on pseudogap formation inα−Al(Mn,Re)Siicosahedral quasicrystalline appro

Cited by 61 publications

References 40 publications

Optimizing the thermoelectric efficiency of icosahedral quasicrystals and related complex alloys

Optimizing the thermoelectric efficiency of icosahedral quasicrystals and related complex alloys

Thermoelectric properties of Al–Pd–Re quasicrystal sintered by Spark Plasma Sintering (SPS): effect of improvement of microstructure

Thermoelectric performance of Al–Pd–Mn quasicrystals: comparison with (1/1, 2/1-)AlPdMnSi approximants and improvement by Ga substitution for Al

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