Phase transition in the binary mixture of jammed particles with large size dispersity

TL;DR

This study reveals a first-order phase transition between two jammed phases in a binary mixture of particles with large size dispersity, characterized by distinct particle participation and elastic properties, with a critical point identified.

Contribution

It provides the first detailed numerical evidence of a first-order phase transition between two jammed phases in highly size-disperse particle mixtures, including phase diagram and mechanical analysis.

Findings

Two distinct jammed phases separated by a first-order transition.

Discontinuous changes in elastic moduli across the transition.

Scaling laws of elastic moduli are consistent with monodisperse systems.

Abstract

It has been well established that particulate systems show the jamming transition and critical scaling behaviors associated with it. However, our knowledge is limited to (nearly) monodisperse systems. Recently, a binary mixture of jammed particles with large size dispersity was studied, and it was suggested that two distinct jammed phases appeared. Here, we conduct a thorough numerical study on this system with a special focus on the statistics of and finite-size effects on the fraction of small particles that participate in the rigid network. We present strong evidence that two distinct jammed phases appear depending on the pressure and composition of two species, which are separated by the first-order phase transition. In one of two phases, only large particles are jammed, whereas both small and large particles are jammed in the other phase. We also describe the phase diagram in the pressure-composition plane, where the first-order phase transition line terminates at a critical point. In addition, we investigate the mechanical properties in terms of the elastic moduli over the phase diagram and find that discontinuous changes in elastic moduli emerge across the phase transition. Remarkably, despite the discontinuities, the elastic moduli in each jammed phase exhibit identical scaling laws to those in the monodisperse systems.