Gases, liquids and crystals in granular segregation

TL;DR

This study experimentally investigates granular segregation in a binary mixture under horizontal oscillation, identifying distinct phases and drawing analogies to colloidal self-assembly.

Contribution

It introduces a detailed phase diagram of granular segregation states and compares them to colloidal self-assembly phenomena.

Findings

Identification of binary gas, segregation liquid, and segregation crystal phases.

Observation of phase transitions with increasing packing fraction.

Analogies established between granular segregation and colloidal self-assembly.

Abstract

We report the results of an experimental investigation of segregation in a binary mixture of dry particles subjected to horizontal oscillatory excitation. The thin layer of particles was driven by the stick--slip frictional interaction with the surface of a horizontal tray. As the packing fraction of the mixture was increased the evolution of distinct phases was observed. We identified them as a binary gas, segregation liquid and segregation crystal and provide both microscopic and macroscopic measures to identify their properties. Finally, we draw some analogies between segregation in our granular system and self-assembly in binary colloidal mixtures.