Electron-energy-loss spectroscopy study of the electronic structure of a stable decagonal quasicrystal Al₇₀Ni₁₅Co₁₅

Electron-energy-loss spectra of a stable decagonal quasicrystal Al₇₀Ni₁₅Co₁₅have been obtained from single-quasicrystal areas of 180 nm diameter. Excitationspectra Al L-shell electrons (L edge) show a sharp onset (Fermi edge) but asmall rise in intensity, indicating the presence of a pseudogap. The onset energyof Al L-edge spectra of the quasicrystal is higher than that of aluminium by0.4 eV, indicating an increase in the covalent nature in the bonding of thequasicrystalline phase as shown earlier by Terauchi et al. The spectra ofvalence electron excitation exhibit a volume plasmon peak at 17.0 eV with afull width at half-maximum (FWHM) value of 5.4 eV. The width showsa stronger damping of the volume plasmon than those sp metals (FWHM, 0.41.5 eV) and sp semiconductors (FWHM, 3-4eV). The origin of the strongdamping is attributed to interband transitions of the d electrons.