Repository logo
 

Supercooled liquids and glasses: dynamics, dynamic heterogeneity, and stability

dc.contributor.authorStaley, Hannah, author
dc.contributor.authorBradley, R. Mark, advisor
dc.contributor.authorSzamel, Grzegorz, advisor
dc.contributor.authorGelfand, Martin, committee member
dc.contributor.authorAristoff, David, committee member
dc.date.accessioned2016-08-18T23:10:12Z
dc.date.available2016-08-18T23:10:12Z
dc.date.issued2016
dc.description.abstractWe used molecular dynamics simulations to study supercooled liquids and glasses. Supercooled liquids are liquids that have been cooled below their freezing temperature. We start the thesis with an introduction on supercooled liquids. We studied several different model glass-formers and compared them by scaling all data to the point where the Stokes-Einstein relation was violated. The Stokes-Einstein relation holds for many liquids, but breaks down at some temperature for most supercooled liquids. In all the systems we studied, we examined dynamic heterogeneity as quantified by the dynamic susceptibility, χ4, and the dynamic correlation length, ξ4. When dynamics are heterogeneous, a liquid breaks up into regions of particles with correlated mobility. The susceptibility is related to the number of particles in such a region, and the dynamic correlation length is related to the size of a region. We broke up our model glass-formers into the categories of strong glass-formers and fragile glass-formers. A strong glass-former has a viscosity, which obeys the Arrhenius relationship, while a fragile glass-former has super-Arrhenius behavior. We compared the systems by relating them at the temperature where the Stokes-Einstein relation was violated. We found that when variables are rescaled to their values at the Stokes-Einstein violation temperature, Ts, the fragile glass-formers all behaved in the same way, and we created plots where the data in all the systems followed the same curve. In the fragile glass-formers, we also found that clusters of correlated particles became compact below Ts. We studied one strong glass-former, and found that it did not match the fragile glass-former curves. However, the Stokes-Einstein violation temperature still appears to be significant in that system, since it appears to mark a change in shape of clusters of correlated particles. However, the clusters did not become compact. We examined the stability of a glass that was created by cooling at different rates. We investigated mechanical stability by measuring the energy and shear modulus of the glass. We also studied the kinetic stability upon heating the glass by examining the average overlap function, a dynamic correlation function. The average overlap function measures how much correlation the positions of particles have with their initial positions after a certain amount of time. We used a stability ratio, S, to probe kinetic stability. Stability is higher in glasses that were prepared by cooling at a slower rate. The different measures of stability have different relationships with initial cooling rate, and we determined that kinetic stability is the best measure of stability.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierStaley_colostate_0053A_13687.pdf
dc.identifier.urihttp://hdl.handle.net/10217/176655
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.titleSupercooled liquids and glasses: dynamics, dynamic heterogeneity, and stability
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplinePhysics
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

Files

Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
Staley_colostate_0053A_13687.pdf
Size:
1.79 MB
Format:
Adobe Portable Document Format