PARTIAL VIBRATIONAL-SPECTRA FOR NI AND NB ATOMS IN THE NI-NB AMORPHOUS SYSTEM

The partial frequency distributions of the individual chemical constit uents and the total vibrational density of states of the amorphous all oy Ni62Nb38 have been measured using neutron inelastic scattering. Sam ples with different Ni isotope composition were involved. The average interaction constant of the Nb atoms with all neighbours is estimated to be about 40% higher than that of the Ni atoms. The low-temperature heat capacity of the amorphous alloys, Ni62Nb38 and Ni44Nb56, has been investigated by the adiabatic method. An increase of the Nb concentra tion decreases the Debye temperature (similar to 3%) and increases the density of the electron states at the Fermi level (similar to 26%). T he temperature dependence of the heat capacity calculated from the exp erimental vibrational density of states of amorphous Ni62Nb38 and a mo del vibrational density of state of Ni44Nb56 were compared with the ex perimental ones. The former gives a better agreement than the latter.