Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

Spatial heterogeneities in structural temperature cause Kovacs’ expansion gap paradox in aging of glasses

Lulli, Matteo, Lee, Chun-Shing, Deng, Hai-Yao, Yip, Cho-Tung and Lam, Chi-Hang 2020. Spatial heterogeneities in structural temperature cause Kovacs’ expansion gap paradox in aging of glasses. Physical Review Letters 124 (9) , 095501. 10.1103/PhysRevLett.124.095501

[thumbnail of PhysRevLett.124.095501.pdf] PDF - Published Version
Download (2MB)

Abstract

Volume and enthalpy relaxation of glasses after a sudden temperature change has been extensively studied since Kovacs’ seminal work. One observes an asymmetric approach to equilibrium upon cooling versus heating and, more counterintuitively, the expansion gap paradox, i.e., a dependence on the initial temperature of the effective relaxation time even close to equilibrium when heating. Here, we show that a distinguishable-particle lattice model can capture both the asymmetry and the paradox. We quantitatively characterize the energetic states of the particle configurations using a physical realization of the fictive temperature called the structural temperature, which, in the heating case, displays a strong spatial heterogeneity. The system relaxes by nucleation and expansion of warmer mobile domains having attained the final temperature, against cooler immobile domains maintained at the initial temperature. A small population of these cooler regions persists close to equilibrium, thus explaining the paradox.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Publisher: American Physical Society
ISSN: 0031-9007
Date of First Compliant Deposit: 9 March 2020
Date of Acceptance: 5 February 2020
Last Modified: 09 Mar 2020 11:15
URI: https://orca.cardiff.ac.uk/id/eprint/130223

Citation Data

Cited 13 times in Scopus. View in Scopus. Powered By Scopus® Data

Actions (repository staff only)

Edit Item Edit Item

Downloads

Downloads per month over past year

View more statistics