Comparative study of the heat capacity of icosahedral quasicrystals in solid and liquid states

Abstract

This study was supported by the Russian Foundation for Basic Research (project no. 10-02-00602-a).The heat capacity of icosahedral quasicrystals Al63Cu25Fe12 and Al62Cu25.5Fe12.5 has been studied at high temperatures up to 1700 K, which is by almost 400 K higher than the melting point of the material. It has been shown that the melt exhibits an excess heat capacity with respect to that determined by the Dulong-Petit law and that is a direct extension of the excess heat capacity of the solid state. It has been concluded that the excess heat capacity is related, as a whole, to the short-range order in the quasicrystal structure. This circumstance allows the identification of the orbital hybridization as the most probable mechanism of formation of the pseudogap in the electronic structure of the quasicrystals

Two-Level Electron Excitations and Distinctive Physical Properties of Al-Cu-Fe Quasicrystals

“…The asymptotic approximation to this limit may be assessed using the Debye model, exactly which we chose to perform. Details can be found in [8,18].…”

“…Intriguing was the [39]). The dash-dotted line (1400) is a fit with the Lorentzian peak according to Equation (8). The dotted line is a residue after subtraction of the peak.…”

“…The dotted line is a residue after subtraction of the peak. Dash-dotted line (5300) is a fit with the Lorentzian peak according to Equation (8). Thick solid line is a fit with a sum of this Lorentzian peak and peaks in (b).…”

“…(b) The residue shown in (a) but on an enlarged scale (solid line). Dash-dotted lines (20,90,250, and 420) are the fit with the Lorentzian peaks according to Equation (8).…”

“…The result of these studies was somehow paradoxical: no physical properties of i-phases assumed from their long-range quasiperiodic nature were identified [7]. Therefore, the long-range icosahedral order and the Hume-Rothery-Jones mechanism (a contact between the Brillouin zone boundaries and the Fermi surface) should be excluded from consideration, both based on the above mentioned paradox and on the fact that TICC-associated thermal effects are observed at temperatures higher than the melting temperature where the zone structure is destroyed [8,9]. The results of numerous experiments carried out to investigate the effect of quasilattice structural perfection on the electrical properties of quasicrystals (see [2] and references therein) also allow the structural disorder and the Anderson localization mechanism to be excluded from consideration.…”