An experimental separation of anharmonic and disorder effects on glassy dynamics
Institut Laue Langevin, BP 156x - F-38042 Grenoble
Cedex 9, France
2 Consejo Superior de Investigaciones Científicas - Serrano 123, E-28006 Madrid, Spain
Accepted: 19 March 1999
Through the study of a polymorphic material, the effects of orientational and structural disorder on the dynamics of glasses are compared to those of anharmonic interactions. The influence of orientational and structural disorder on the Grüneisen parameters has been separated combining the pressure dependence of the density of states with the molar volume of each phase. The results show that the two phases exhibiting glassy behavior have different anharmonic properties, and that this anharmonicity difference is responsible for most of the observed differences in their low-temperature specific heats.
PACS: 62.20.-x – Mechanical properties of solids / 63.50.+x – Vibrational states in disordered systems / 65.70.+y – Thermal expansion and density changes; thermomechanical effects
© EDP Sciences, 1999