Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
DY: Fachverband Dynamik und Statistische Physik
DY 61: Poster - Glasses
DY 61.4: Poster
Donnerstag, 19. März 2015, 16:00–18:00, Poster A
Theory of heterogeneous viscoelasticity — •Walter Schirmacher1,2,3, Giancarlo Ruocco3, and Valerio Mazzone3 — 1Universität Innsbruck — 2Universität Mainz — 3Università "La Sapienza" Roma
We present a new theory of viscoelasticity of a glass-forming viscous liquid near and below the glass transition. In our model we assume that each point in the material has a specific viscosity, which varies randomly in space according to a fluctuating activation free energy. We include a Maxwellian elastic term and assume that the corresponding shear modulus fluctuates as well with a similar distribution as that of the activation barriers. The model can be mapped to an effective heterogeneous elasticity theory, which is solved in coherent-potential approximation (CPA). The theory predicts an Arrhenius-type temperature dependence of the viscosity in the vanishing-frequency limit, independent of the distribution of the activation energies. It is shown that this activation energy is generally different from that of a diffusing particle with the same barrier-height distribution. At finite, but low frequencies the theory describes low-temperature alpha relaxation together with the beta wing. Good agreement with data on metallic glasses is obtained. At high frequencies the theory reduces to heterogeneous elasticity theory, which explains the occurrance of the boson peak and related vibrational anomalies.