Doctoral Dissertations

Author

Xiangyu Fang

Abstract

"The effect of melting history on the iron redox equilibrium, structure, crystallization and properties of a binary iron phosphate glass with a 40Fe2O3-60P2O5 mol%, batch composition were investigated. The structure and properties of single and mixed alkali iron phosphate glasses were also studied. Mössbauer, Raman and infrared spectroscopy were used to determine the changes in the concentration of iron ions and phosphate units in the structure. Differential thermal analysis, X-ray diffraction and thermogravimetric analysis were used to investigate crystallization. Density, molar volume, thermal expansion, dc electrical conductivity and dielectric constant and loss tangent were measured. The heat capacity and glass transition behavior of the glasses was also measured by the differential scanning calorimeter method.

The effect of the melting temperature is stronger than the melting time on the concentration of Fe2+ ions in iron phosphate glasses. The pyrophosphate network in iron phosphate glasses and their general properties do not change either with melting temperature and time or with adding up to 20 mol% of single and mixed alkali oxides. The dissolution rate (in deionized water) of these glasses is generally very low (~10-9 g/cm2/min) and nearly independent of the relative concentration of Fe2+ or Fe3+ ions. The dissolution rate of the iron phosphate glasses containing 20 mol% of single or mixed alkali oxide can be comparable to that of window glass. There is no mixed alkali effect in the iron phosphate glasses. The crystallization tendency indicates that the glass structure becomes closer to that of crystalline Fe3(P2O7)2 with increasing concentration of Fe2+ ions in the glass. The large fragility parameters indicates that the iron phosphate glasses belong in the category of the fragile glass-forming liquids"--Abstract, page v.

Advisor(s)

Day, D. E.

Committee Member(s)

Brow, Richard K.
Kohser, Ronald A.
Ownby, P. D.
Mattox, Douglas M.

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Ceramic Engineering

Publisher

University of Missouri--Rolla

Publication Date

Spring 2000

Journal article titles appearing in thesis/dissertation

  • The effect of melting history on the iron redox equilibrium, structure, crystallization and properties of an iron phosphate glass
  • Structure and properties of mixed alkali iron phosphate glasses
  • Glass transition behavior and fragility of iron phosphate glasses

Pagination

xix, 179 pages

Note about bibliography

Includes bibliographical references.

Rights

© 2000 Xiangyu Fang, All rights reserved.

Document Type

Dissertation - Restricted Access

File Type

text

Language

English

Thesis Number

T 7751

Print OCLC #

45893378

Electronic OCLC #

1079365478

Link to Catalog Record

Electronic access to the full-text of this document is restricted to Missouri S&T users. Otherwise, request this publication directly from Missouri S&T Library or contact your local library.

http://laurel.lso.missouri.edu/record=b4510763~S5

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