Low frequency excitations in vitreous silica

✍ Scribed by A.J. Dianoux; U. Buchenau; M. Prager; N. Nücker

• Publisher: Elsevier Science
• Year: 1986
• Weight: 350 KB
• Volume: 138
• Category: Article
• ISSN: 0378-4363
• DOI: 10.1016/0378-4363(86)90006-9

✦ Synopsis

Inelastic neutron scattering from vitreous silica reveals that, in addition to the sound waves, there is a strong contribution from other vibrational modes in the frequency region above 150 GHz. From an analysis of their inelastic structure factor, we have put forward a simple model which can describe satisfactorily the measured data. The additional modes are identified as coupled rotations of SiO4 tetrahedra and their density of states is determined on an absolute scale. The specific heat calculated from this density of states, in addition to the Debye term, is in good agreement with data in the literature. Some comments are made on the fracton interpretation of the vibrational density of states of amorphous solids.