Effect of Densification on the Density of Vibrational States of Glasses

We studied the effect of densification on the vibrational dynamics of a ${\mathrm{Na}}_2{\mathrm{FeSi}}_3{\mathrm{O}}_8$ glass. The density of vibrational states (DOS) has been measured using nuclear inelastic scattering. The corresponding changes in the microscopic, intermediate-range, and macroscopic properties have also been investigated. The results reveal that, in the absence of local structure transformations, the Debye level and the glass-specific excess of vibrational states above it have the same dependence on density, and the evolution of the DOS is fully described by the transformation of the elastic medium.

Figure 1

Reduced density of vibrational states of the initial and densified ${\mathrm{Na}}_2{\mathrm{FeSi}}_3{\mathrm{O}}_8$ glasses. The dashed line emphasizes the shift of the peak position on densification. The thin lines show the consistency of the data with the calculated Debye levels indicated by symbols at $E=0$.

Figure 2

Characterization of the microscopic and intermediate-range structure of the initial and densified glass using (a) conversion electron Mössbauer spectroscopy (the spectra are normalized to an equal area) and (b) x-ray scattering.

Figure 3

Dependence on densification of (a) density and (b) longitudinal acoustic frequency measured by Brillouin light scattering in backscattering geometry. The dashed line emphasizes the shift of the longitudinal mode with pressure.

Figure 4

Reduced density of states after rescaling the energy axes in Debye energy units and the corresponding renormalization of the DOS area. The thin lines emphasize the consistency of the data with the Debye level $g(\epsilon )/{\epsilon }^2=3$.