Incompressibility of polydisperse random close packed colloidal particles

TL;DR

This study uses confocal microscopy and a new algorithm to analyze the compressibility of polydisperse colloidal particles in random close packing, revealing hyperuniformity and the importance of considering particle size.

Contribution

Introduces an algorithm to estimate individual particle sizes and demonstrates the significance of size consideration in compressibility analysis of colloidal packings.

Findings

Compressibility vanishes linearly as wave vector approaches zero.

Particle size consideration is crucial for accurate compressibility calculation.

Experimental packing exhibits hyperuniformity.

Abstract

We use confocal microscopy to study a random close packed sample of colloidal particles. We introduce an algorithm to estimate the size of each particle. Taking into account their sizes, we compute the compressibility of the sample as a function of wave vector $q$, and find that this compressibility vanishes linearly as $q \rightarrow 0$. The particle sizes must be considered to calculate the compressibility properly. These results also suggest that the experimental packing is hyperuniform.