ELECTRONIC SPECIFIC-HEAT MEASUREMENTS FOR QUASI-CRYSTALS AND FRANK-KASPER CRYSTALS IN MG-AL-AG, MG-AL-CU, MG-AL-ZN, MG-GA-ZN AND AL-LI-CU ALLOY SYSTEMS

The electronic specific heat coefficient was measured for sp electron quasicrystals and the corresponding Frank-Kasper crystals in Mg-Al-Ag, Mg-Al-Cu, Mg-Al-Zn, Mg-Ga-Zn and Al-Li-Cu alloy systems. It turned out that the ratio gamma-exp/gamma-F plotted against the average number of electrons per atom is essentially identical between the quasicrystalline and Frank-Kasper phases: it decreases with decreasing electron concentration per atom, e/a, and is extrapolated to zero at about e/a = 2.0. A unique e/a dependence of the gamma-exp/gamma-F in the Frank-Kasper phase is discussed in terms of the Fermi surface-Brillouin zone interaction specific to this structure. Judging from the identical e/a dependence of gamma-exp/gamma-F, we conclude that a similar Fermi surface-Brillouin zone interaction ought to be essential in determining the density of states at the Fermi level in the quasicrystalline phase. The electronic structure near the Fermi level is essentially determined by the local atomic structure, which happens to be similar between these two intriguing phases.