Article abstract
Nature Materials 7, 556 - 561 (2008)
Published online: 22 June 2008 | doi:10.1038/nmat2219
Subject Categories: Glasses | Colloids
Direct observation of a local structural mechanism for dynamic arrest
C. Patrick Royall1,2, Stephen R. Williams3, Takehiro Ohtsuka2 & Hajime Tanaka2
Abstract
The mechanism by which a liquid may become arrested, forming a glass or gel, is a long-standing problem of materials science. In particular, long-lived (energetically) locally favoured structures (LFSs), the geometry of which may prevent the system relaxing to its equilibrium state, have long been thought to play a key role in dynamical arrest. Here, we propose a definition of LFSs which we identify with a novel topological method and directly measure with experiments on a colloidal liquid–gel transition. The population of LFSs is a strong function of (effective) temperature in the ergodic liquid phase, rising sharply approaching dynamical arrest, and indeed forms a percolating network that becomes the 'arms' of the gel. Owing to the LFSs, the gel is unable to reach equilibrium, crystal–gas coexistence. Our results provide direct experimental observation of a link between local structure and dynamical arrest, and open a new perspective on a wide range of metastable materials.
- School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
- Research School of Chemistry, The Australian National University, Canberra, ACT 0200, Australia
Correspondence to: C. Patrick Royall1,2 e-mail: paddy.royall@bristol.ac.uk
Correspondence to: Hajime Tanaka2 e-mail: tanaka@iis.u-tokyo.ac.jp
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