# Charging changes contact composition in binary sphere packings

## TL;DR

This study demonstrates that tribo-charging influences contact composition in binary sphere packings, enabling control over local granular material properties without causing global segregation.

## Contribution

It reveals how tribo-charging affects contact types in binary sphere packings, offering a new method to tune granular material properties.

## Key findings

- Charge density alters contact numbers between same and opposite types.
- No global segregation occurs despite charge-dependent contact changes.
- Tribo-charging can be used to modify local contact composition.

## Abstract

Equal volume mixtures of small and large polytetrafluorethylene (PTFE) spheres are shaken in an atmosphere of controlled humidity which allows to also control their tribo-charging. We find that the contact numbers are charge-dependent: as the charge density of the beads increases, the number of same-type contacts decreases and the number of opposite-type contacts increases. This change is not caused by a global segregation of the sample. Hence, tribo-charging can be a way to tune the local composition of a granular material.