Observation of Scaling Behaviour of Dynamic Correlations near Liquid-Glass Transition

Abstract

A time-of-flight inelastic neutron scattering study of Ca0.4K0.6(NO3)1.4 of the temperature dependence of the dynamic structure factor revealed a clear frequency-independent signature of the glass transition at the conventional transition temperature Tg. Above Tg the data combined with our previous neutron spin echo results display two relaxation processes at well-separated frequencies. The faster process was now found to be consistent with a scaling behaviour corresponding to a critical-type slowing-down when approaching a certain temperature T0, as predicted by recent mode coupling theories. The variation of various properties consistently points to a critical temperature T0 of about 30 K above Tg = 333 K.

The Essentials of the Mode-Coupling Theory for Glassy Dynamics

“…The critical spectrum was first identified for the mentioned mixed salt CKN. Neutron-scattering spectra, testing density fluctuations for microscopic distances [38], polarized-light-scattering spectra [39], testing fluctuations for macroscopic distances, and depolarized-light-scattering data [39] showed the spectral enhancement compatible with equation (6) for a = 0.30±0.05. Recently a break through in the dielectric-loss spectroscopy was achieved, allowing one to use this classical probing of the dynamics in the full GHz-window.…”

Dynamics of PEO in Blends with PMMA: Study of the Effects of Blend Composition via Quasi-Elastic Neutron Scattering

“…In pure polymers, the nature of the fast process has been described as a vibrational 62 process and an intramolecular relaxation process. [63][64][65][66] Characteristic times for this process are weakly dependent on temperature and follow an Arrhenius scaling. The slow process refers to the structural relaxation of the polymer which is usually associated with the R-relaxation.…”

Multiple-scattering effects on smooth neutron-scattering spectra

“…Further predictions are made for the critical temperature dependence of h x and t σ . Many neutron scattering experiments [3,[14][15][16][17][18][19][20][21][22] have been undertaken to test these predictions. However, the asymptotic law (11) holds only in a restricted frequency range, and therefore it cannot be used as input to a multiple-scattering calculation.…”