Shear-switched bi-stability in binary suspensions

Condensed Matter lunchtime seminar

Shear-switched bi-stability in binary suspensions

  • Event time: 1:00pm until 2:00pm
  • Event date: 19th August 2019
  • Speaker: (School of Physics & Astronomy, University of Edinburgh)
  • Location: Room 2511,

Event details

Concentrated binary suspensions (or slurries) containing large grains suspended in a colloidal gel background are ubiquitous in applications such as lithium-ion battery catholytes. For efficient and effective processing, it is vital to understand how they flow. We uncover surprising complexity in the rheology of a well-characterised model system: non-Brownian repulsive silica particles suspended in a background of attractive silica particles that are ten times smaller. Routine laboratory operations revealed that our suspensions could be switched reversibly by shear between solid- and liquid-like states. Confocal rheometry showed respectively large particles homogeneously dispersed in a background colloidal gel matrix in the solid state, and compact clusters of small particles dispersed amongst large particles in the liquid state. Mapping out a rheological state diagram uncovered a very low shear regime in which the system became strongly history dependence. These complexities disappeared when the large particles became small enough to penetrate the fractal clusters forming the background colloidal gel. We enunciate design principles for tuning the microstructure and rheology of such binary suspensions.

About Condensed Matter lunchtime seminars

This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..

Find out more about Condensed Matter lunchtime seminars.