Vibrational and Electronic Properties of the Amorphous Systems Ni_(44)Nb_(56), Ni_(62)Nb_(38), and Cu_(33)Zr_(67) as Derived from Specific Heat Measurements

摘要

The specific heats of the amorphous systems Ni_(44)Nb_(56), Ni_(62)Nb_(38), and Cu_(33)Zr_(67) were studied in the temperature range 3-273 K. The data obtained allow one to isolate the contribution due to atomic vibrations from the experimentally measured specific heat, to determine the density of electronic states at the Fermi level and the temperature dependence of the characteristic Debye parameter Θ over a broad temperature range, and to calculate a few frequency moments that characterize the vibrational spectrum. The information derived on the average characteristics of vibrational spectra is in good agreement with earlier data on inelastic neutron scattering. In transferring from Ni_(44)Nb_(56) to Ni_(62)Nb_(38), the density of electronic states at the Fermi level decreases and the characteristic vibrational frequencies increase. The density of electronic states at the Fermi level for Cu_(33)Zr_(67) is close to that for Ni_(62)Nb_(38). The characteristic frequencies of the vibrational spectrum of the Cu_(33)Zr_(67) system are substantially lower (by 30%) than those of the Ni_(44)Nb_(38) systems.