Related Experiment Video
Updated: Jan 10, 2026

Studying Large Amplitude Oscillatory Shear Response of Soft Materials
Published on: April 25, 2019
Correlation between Fast Relaxation, Shear Phonon Propagation, and Dynamic Heterogeneity in Glass-Forming Liquids
Peng Luo1, Yanqin Zhai1,2, Zhikun Cai1,2
1Beckman Institute for Advanced Science and Technology, University of Illinois Urbana─Champaign, Urbana, Illinois 61801, United States.
Abstract:
Fast relaxation is the precursor to α-relaxation, yet its microscopic origin and role in the emergence of glassy dynamics remain elusive. Using inelastic neutron scattering on the fragile glass-former Ca0.4K0.6(NO3)1.4, we show that the fast relaxation dynamics are strongly modulated by local structure and exhibit a distinct temperature dependence that correlates with shear phonon propagation and the Arrhenius-to-super-Arrhenius crossover of α-relaxation. These results indicate that fast relaxation arises from the interplay of shear phonon softening and local structural arrangements, serving as the intermediate dynamical process that connects the elastic interactions to kinetic facilitation underlying the emergence of dynamic heterogeneity in supercooled liquids.
Related Concept Videos
Speed of Sound in Solids and Liquids
Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
Deriving the Speed of Sound in a Liquid
The speed of sound in fluids can be derived by considering a mechanical wave...
Elastic Strain Energy for Shearing Stresses
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to...
Atomic Nuclei: Types of Nuclear Relaxation
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers...

