Structure and Lengthscales in Glassy Systems

Abstract

The study of structure in glassy systems is a study of lengthscales. In experiment we try to access those lengthscales directly with particle resolved systems. Improved microscopy techniques have allowed us to make real space measurements of smaller particle systems than ever before which allows us to access new glassy lengthscales to inform the theory of the glass transition. In Chapter 4 we assess current methods and look at the development of new methods for the measurement of dynamical heterogeneity, one of the key pieces in the puzzle of the glass transition. In Chapter 6 we then apply these methods to the system of colloidal hard spheres where we study some of the most supercooled real space particle resolved systems ever. Another important aspect of smaller particle suspensions is that density matching of particle suspensions can be neglected for short timescale experiments. This gives access to new experimental systems which were not previously accessible. One such system is the "Mermaid" potential also studied in 6, a system of charged particles in a high dielectric constant solvent where the relevant structural lengthscales are set by the charge repulsion and polymer depletion interactions. In Chapter 9 we consider development of a method for measuring structure in dense systems. The correlations of these structures are a key piece of the puzzle to understand the role of structure in glassy systems. We then apply this method to simulations of crystallisation in the 2:1 ratio Kob-Andersen glassformer in Chapter 8 where the behaviour of the system is dependent on the interactions of a particular favoured structural motif.

Date of Award	28 Nov 2019
Original language	English
Awarding Institution	The University of Bristol
Supervisor	C P Royall (Supervisor)