W0196: Evidence for Polyamorphism in Se-As-Ge Glasses from Neutron Inelastic Scattering

Evidence for Polyamorphism in Se-As-Ge Glasses from Neutron Inelastic Scattering. * Birgit Effey ¹, D. A. Drabold ¹, W. A. Kamitakahara ², and R. L. Cappelletti ¹, ¹Condensed Matter and Surface Sciences Program, Department of Physics and Astronomy, Ohio University, Athens, OH 45701, ²NIST Center for Neutron Research, Gaithersburg, MD 20899

Covalent network glasses of the Se-As-Ge system display several features which depend simply on average coordination number <r>. Examples of such “isocoordinate rules” are the behaviors of the glass transition temperature and the vibrational density of states (VDOS) determined by neutron inelastic scattering. The latter rule has some notable exceptions along and near the Se-As binary line. For <r> > 2.4 sharp features appear in the VDOS at certain composition-independent frequencies pointing to the existence of robust molecular cluster-like entities. We propose that these entities constitute a second amorphous phase embedded in the network.