The electronic properties of a large number of icosahedral-crystal systems have been studied experimentally. These systems include alloys of the simple metals and those that contain transition metals. Some of the icosahedral phases (i-phases) are thermally stable while others are metastable; and their degree of structural order varies within each of the stability classes. The importance of sample quality to the exposition of intrinsic properties is emphasized, particularly for systems with high resistivities. As a result, experiments on single-phase samples from the diversity of systems studied have shed light on the physics of quasicrystalline alloys. Comparison made with the approximant and amorphous phases have provided important insights to the understanding of quasicrystallinity, randomness, and atomic-potential effects on electronic properties. Reduction in the electronic density of states (DOS) at the Fermi level relative to the free-electronic value is observed in the stable i-phase syste...

Electronic properties of quasicrystals an experimental review

The low-temperature specific heat (1.5 K to 6 K), the electrical resistivity (1 K to room temperature) and the magnetoresistance at 1.4, 4.2 and 10 K have been measured for the single-grained I-phase of Al–Li–Cu with near 6:4:1 composition grown by the Bridgman method. An etching method, which allows us to dissolve only the fcc Al second phase completely, was developed. The density of states at the Fermi energy obtained from the electronic specific heat coefficient is extremely small compared with the corresponding free-electron value. The resistivity at 4.2 K is as high as 870 µΩcm and decreases as \({-}{\sqrt{T}}\) below 20 K and as - T above 20 K, indicating the development of the weak localization of electrons. Magnetic field dependence of the magnetoresistance is consistent with the theory of the localization without involving electron-electron interaction.

Electronic Properities of the Single-Grained Icosahedral Phase of Al-Li-Cu

Role of icosahedral phase in enhancing the strength of Mg–Sn–Zn–Al alloy

The formation of quasicrystals and related approximant crystalline phases is studied in the Mg-Al-Zn alloy system by applying mechanical alloying technique. This technique is advantageous over the conventional melt-spinning because of the ease in sample preparation involving only the solid-state reaction. The quasicrystal is formed over a wide composition range. Those formed along the Bergman line corresponding to Mg 39.5 , (Al 1-x Zn x ) 60.5 are found to be metastable and to transform into stable (1/1-1/1-1/1) Frank-Kasper phase by evolving an exothermic peak in the DSC run. Its stability is found to increase with decreasing Al content

Formation of quasicrystals and approximant crystals by mechanical alloying in Mg-Al-Zn alloy system

The present study of rapidly solidified melt-spun Al80Fe14Si6 Al80V14Si6, and Al80Fe10V4Si6 alloys by electron microscopy techniques, x-ray diffractometry, and differential scanning calorimetry leads to a number of microstructural results. Coexistence of a micro-quasicrystalline state of an icosahedral phase with monoclinic theta -Al13Fe4 and hexagonal beta -Al6V in Al-Fe-Si and Al-V-Si alloys, respectively, is reported. Also, the growth morphology of the icosahedral phase surrounded by a crystalline ring was investigated in an Al-Fe-V-Si alloy. The crystalline ring has the particles of the cubic alpha -Al-12(Fe,V)(3)Si silicide phase. Evidence of irrational twinning of cubic crystals, giving rise to a symmetry not deviating much from icosahedral symmetry was found in this alloy. In all the three alloys crystalline intermetallics were elucidated in the context of rational approximants of an icosahedral quasicrystal. It was noticed that while the icosahedral phase in Al-Fe-Si and AI-V-Si alloys transforms o crystalline intermetallics at about the same temperature (approximately 610 K), the transformation of icosahedral phase in Al-Fe-V-Si alloy occurred at a relatively lower temperature (540 K). The origin of different metastable microstructures and their stability at elevated emperatures, in these alloys, are compared and discussed.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400068941

Microstructural characterization of rapidly solidified Al–Fe–Si, Al–V–Si, and Al–Fe–V–Si alloys

Production of Al-Based Ternary and Quaternary Icosahedral Phases

Electrical Properties of Single Phase Al-Based Quasicrystals

Local Atomic Configuration Studied by Mössbauer Spectroscopy and Crystallographic Texture in Al-Mn Based Quasicrystals

http://link.springer.com/content/pdf/10.1007/978-94-009-3757-4_74.pdf

Possible Sphere Packings of Quasicrystal

Cu3.21Bi4.79S9 was synthesized from Cu, Bi and S element powders using mechanical alloying method. The formation of Cu3.21Bi4.79S9 was identified using XRD and the changes of morphologies of the mixtures of Cu, Bi, and S powders during milling were observed using table top SEM. The milled powders were sintered using Hot-isostatic pressing at 230°C with a pressure of 50 MPa. Electrical resistivity and Seebeck coefficient of sintered samples were measured using ZEM-3 (Electrical resistivity and Seebeck Coefficient measuring System). Cu3.21Bi4.79S9 and some secondary phases were found in the 5h milled powder but single phase Cu3.21Bi4.79S9 was only obtained after milling for 15 h. A minimum electrical resistivity of sintered Cu3.21Bi4.79S9 sample was found to be 0.66 Ω.m at 170°C. We observed that a n- to p-type conversion at temperature of around 75 °C. However, a maximum n-type Seebeck coefficient of Cu3.21Bi4.79S9 was of -214 μV/K at 45 °C. The Seebeck coefficient decreases with increasing temperature and it reaches zero value at around 75 °C and then p-type Seebeck coefficient increases with increasing the temperature. The maximum p-type Seebeck coefficient was observed of 202 μV/K at 170°C.

Kaoru Kimura

Papers

Production of Al-Based Ternary and Quaternary Icosahedral Phases

Electrical Properties of Single Phase Al-Based Quasicrystals

Local Atomic Configuration Studied by Mössbauer Spectroscopy and Crystallographic Texture in Al-Mn Based Quasicrystals

Possible Sphere Packings of Quasicrystal

Evaluation of Thermoelectric Properties of Cu3.21Bi4.79S9 Bismuth Chalcogenide