Doctoral Dissertations

Keywords and Phrases

Crystallization; Dissolution; Glass stability; Iron phosphate glasses; Iron redox ratio; Optical basicity


“Iron phosphate glasses with Fe/P = 0.33 - 0.67, O/P = 3.0 - 3.5 and Fe2+/ΣFe = 0.16- 0.52 were prepared by altering batch compositions and melt conditions. Thermal analyses indicate polyphosphate glasses with intermediate chain lengths are most stable against devitrification. Heterogeneous crystallization occurs on the glass surface and is dependent on iron valence state, particle size, heating rate, temperature and oxygen availability in the atmosphere. Oxidation of ferrous iron on the glass surface occurs at temperatures as low as Tg, and thus crystallization behavior and stability can be altered via post-melt heat treatments. A novel preparation of thin glass “bubbles” was developed to allow examination of iron phosphate glasses using optical spectroscopy. Absorption near ~476 nm was determined to be predictive of iron valence state, and a deconvolution method is proposed to analyze iron coordination environments. Two models were developed using optical basicity and a statistical, bonding-level representation of the glass structure to investigate the effects of composition on iron redox equilibria and aqueous dissolution behavior. A new approach of calculating heats of formation from group basicities yields a linear correlation with thermochemical data for equivalent crystalline compounds, and the thermodynamic model of iron redox equilibria predicts trends in melt viscosity with bulk basicity, chain length and alkali mixing. An empirical fit of the model predicts iron redox ratios of glasses prepared here within experimental uncertainty. The bond hydration model yields similar spread in predicted versus experimental dissolution rates as previously established models based on free energies of hydration, yet is based solely on composition with no requisite for thermochemical data.”--Abstract, page iii.


Brow, Richard K.

Committee Member(s)

Fahrenholtz, William
Switzer, Jay A., 1950-Smith, Jeffrey D.
Kim, Cheol-Woon, 1966-


Materials Science and Engineering

Degree Name

Ph. D. in Materials Science and Engineering


Missouri University of Science and Technology

Publication Date

Spring 2022


xix, 257 pages

Note about bibliography

Includes bibliographic references (pages 232-256).


© 2022 Melodie Linda Schmitt, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 12133