Pressure dependence of the Boson peak in glassy As2S3 studied by Raman scattering

• Published in: Journal of non-crystalline solids Vol. 352; no. 42-49; pp. 4594 - 4600
• Main Authors: Andrikopoulos, K.S., Christofilos, D., Kourouklis, G.A., Yannopoulos, S.N.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 15-11-2006; Elsevier
• Subjects: Chalcogenides; Condensed matter: structure, mechanical and thermal properties; Disordered solids; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Glass transition; Glass transitions; Glasses; Lattice dynamics; Medium-range order; Phonons; Physics; Pressure effects; Raman scattering; Short-range order; Specific phase transitions; Structure of solids and liquids; crystallography; Vibrational states in disordered systems; Glass transition; Chalcogenides; 62.50.+p; 63.50.+x; Pressure effects; Raman scattering; Phonons; Short-range order; 64.70.Pf; 61.43.Dq; Medium-range order; Raman spectra; Dimensionality; Arsenic sulfides; Medium range order; Phonon density of states; Glass structure; Spectral line shift; Chalcogenide glasses; High pressure; Boson peak
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2005.12.056

A detailed pressure dependence study of the low energy excitations of glassy As2S3 is reported over a wide pressure range, up to 10GPa. The spectral features of Boson peak are analyzed as a function of pressure. Pressure effects on the Boson peak are manifested as an appreciable shift of its frequency to higher values, a suppression of its intensity, as well as a noticeable change of its asymmetry leading to a more symmetric shape at high pressures. The pressure-induced Boson peak frequency shift agrees very well with the predictions of the soft potential model over the whole pressure range studied. As regards the pressure dependence of the Boson peak intensity, the situation is more complicated. It is proposed that in order to reach proper conclusions the corresponding dependence of the Debye density of states must also be considered. Comparing the low energy modes of the crystalline counterpart of As2S3, as well as the experimental data concerning the pressure dependencies of the Boson peak frequency and intensity, a structural or glass-to-glass transition seems to occur at the pressure ∼4GPa related to a change of local dimensionality of the glass structure. Finally, the pressure-induced shape changes of the Boson peak can be traced back to the very details of the excess (over the Debye contribution) vibrational density of states.