Propagating vibrational modes in the Zr–Be metallic glasses

The dynamic structure factors, S(Q,E), for the Zr70Be30, Zr60Be40 and Zr50Be50 metallic glasses have been measured using neutron inelastic scattering on the IN4 spectrometer (ILL, Grenoble, France), over the range of momentum transfers and energy transfers 2 < E (meV) < 60. The constant-Q cuts through the dynamic structure factor and longitudinal current correlation function, Jl(Q,E), were obtained. The dispersion relations for two representations, S(Q,E) and Jl(Q,E), were derived by fitting a Gaussian to the peaks. The specific low-energy modes (~5 meV) as well as 'acoustic-phonon like' (~16 meV) and 'optic-phonon like' excitations (~47 meV) were observed in these metallic glasses with disparate mass and ionic radius components.