Fluctuations in Bulk and Thin Film Glasses
Open Access
- Author:
- Kirchner, Katelyn
- Graduate Program:
- Materials Science and Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 02, 2024
- Committee Members:
- John Mauro, Program Head/Chair
Robert Kimel, Major Field Member
Seong Kim, Outside Unit & Field Member
John Mauro, Chair & Dissertation Advisor
Ismaila Dabo, Major Field Member
Sushmit Goyal, Special Member - Keywords:
- Statistical mechanics
Glass
Thin film silica
Structure
Fluctuations
Ion exchange - Abstract:
- Atomic structure dictates the behavior of all material systems. Typically, structural averages or unit cell representations are used to predict structure-property-performance relationships. A defining characteristic of glassy materials is the disordered atomic arrangement, which induces localized distributions in structural features (called fluctuations, heterogeneities, or variances). To facilitate performance optimization of industrial glasses, there is a growing need for mathematical models that quantify the effects of atomic fluctuations as a function of glass processing parameters. This dissertation focuses on the development of robust physics-based techniques to quantify the formation of structural fluctuations and evaluate structural adaptation during the industrial chemical strengthening process. Major advances include quantification of fluctuations in structural unit formation, rigidity, ring size, local density, and topology to optimize glass properties and behaviors including crack propagation, Rayleigh scattering, and ion exchange. The knowledge delineated for bulk oxide glasses is then used to investigate which structural features govern thermal conductivity in thin film silica. Experimental and computational results reveal the pivotal role of nanometer-sized voids, bonding fluctuations, and topographical fluctuations on the thermal behavior of SiO2 bulk and thin films. This dissertation evaluates eight types of structural fluctuations, viz., variations in rigidity, population of structural units, topology, void size, local density, chemistry, topography, and ring size, in the context of novel theoretical model development, experimental thin film synthesis and characterization, and molecular dynamics simulations of bulk and thin film glasses. Scientific advancement and socioeconomic benefits are realized through improved fundamental understanding of the formation of the glassy structure and the ability to design optimized glasses at the atomic scale for next-generation applications, including damage-resistant electronic displays, safer pharmaceutical vials to store and transport vaccines, lower-attenuation fiber optics, and thinner thermal-resistant battery and memory storage devices. We invite the reader to join us in exploring what can be discovered by going beyond the average.