Dynamics of colloidal particles in ice

TL;DR

This study investigates how colloidal particles behave within polycrystalline ice using X-ray Photon Correlation Spectroscopy, revealing temperature-dependent ballistic motion linked to ice grain boundary migration.

Contribution

The paper introduces the use of XPCS to analyze colloidal dynamics in ice, highlighting the role of grain boundary migration in particle motion.

Findings

Particles in high-density regions exhibit ballistic motion.

Particle velocity increases with temperature.

Motion is linked to ice grain boundary migration.

Abstract

We use X-ray Photon Correlation Spectroscopy (XPCS) to probe the dynamics of colloidal particles in polycrystalline ice. During freezing, the dendritic ice morphology and rejection of particles from the ice created regions of high-particle-density, where some of the colloids were forced into contact and formed disordered aggregates. We find that the particles in these high density regions underwent ballistic motion coupled with both stretched and compressed exponential decays of the intensity autocorrelation function, and that the particles' characteristic velocity increased with temperature. We explain this behavior in terms of ice grain boundary migration.