Mixed Modifier Effect in Aluminosilicate Glasses
Restricted (Penn State Only)
- Author:
- Lin, Yinan
- Graduate Program:
- Materials Science and Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- December 06, 2021
- Committee Members:
- Hojong Kim, Major Field Member
John Mauro, Chair & Dissertation Advisor
John Mauro, Program Head/Chair
Robert Kimel, Major Field Member
Seong Kim, Outside Unit & Field Member - Keywords:
- aluminosilicate-based glass
dissolution
dynamic
mixed modifier effect.
aluminosilicate glass
mixed modifier effect
mechanical
glass transition - Abstract:
- The objectives of this PhD study are to gain insights into mass transport-related properties, e.g., glass transition temperature, Vickers hardness, and activation energy of dynamic dissolution, of mixed modifier aluminosilicate glasses and gain a coherent understanding of the mechanism of mass transfer. The primary objective is to propose and apply an experimental framework that can be capable of predicting these properties for multicomponent glasses containing mixtures of network modifiers. Pairwise and ternary interactions are examined experimentally to understand the mixed modifier effect (MME) in a series of ternary modifier containing (Na2O·K2O·CaO) aluminosilicate glasses. The pairwise model follows from the work of LaCourse [LaCourse WC. A defect model for the mixed alkali effect. J Non-Cryst Solids. 1987;95-96:905–912.]. By keeping the glass network former concentration constant and adjusting the molar ratios of the three network modifiers, the glass transition temperature (Tg), Vickers hardness (Hv) and activation energy (Ea) for aqueous dissolution of each modifier cation are investigated. We examine whether the pairwise interaction model is sufficient, or if ternary interactions also need to be included to predict the MME in these more complicated glass systems. This work reveals that the pairwise model can be used to predict the mixed modifier effect for Tg in complex multiple-modifier glass system by solely using a combination of binary systems involving the two-body interaction factors. However, ternary mixed-modifier interactions are present in other properties such as Hv and Ea. The outcomes suggest pathways that could be used to improve the chemical durability of aluminosilicate glasses by compositional alternations that enhance network rigidity.