A model of an icosahedron-based random-network is constructed by using a Bethe lattice, and the vibrational spectrum has been calculated. Reasonable agreement with experimental spectra from amorphous boron is obtained. Comparison to the phonon spectra of crystalline boron with a similar structure shows the importance of the correlation in the phase of displacements between adjacent icosahedra. The even and odd vibrations have distinct frequencies in the crystal case. In a random network, the difference in the phase between intermolecular bonds is averaged, so that the highest frequency band becomes both IR and Raman active.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry