Masters Theses

Abstract

"A study was made of the ZnO-Fe₂O₃-Fe₃O₄ system at 1200ºC using oxygen pressures between 0.1 and 1x10⁻⁴ atmospheres. The results of this study were used to calculate the activities of ZnO, Fe₂O₄, and Fe₃O₄ in the spinel solid solution region of this ternary system. The activities of ZnFe₂O₄ and Fe₃O₄ across the pseudo-binary system were then calculated. The activities of the components in both the ternar and pseudo-binary systems exhibited large positive deviations from Raoult's Law, being more pronounced at the higher Fe₃O₄ content. The free energy, enthalpy, and entropy of mixing of the pseudo-binary system ZnFe₂O₄-Fe₃O₄ at 1200ºC were calculated from the activities of ZnFe₂O₄ and Fe₃O₄. The entropy of mixing was compared with the entropy of mixing calculated from two statistical models, one representing an ideal solution, and the other representing the mixing of a normal with an inverse spinel. The pseudo-binary entropy of mixing appeared to compare the best with the model of the mixing of a normal with an inverse spinel. This indicates that the cations of a normal and an inverse spinel tend to occupy the same positions in the spinel solid solution lattice that they would occupy in their respective pure components. This comparison also indicates that the cation distribution in the spinel solid solution is an important factor in determining the thermodynamic properties of the spinel solid solution"--Abstract, page ii.

Advisor(s)

O'Keefe, T. J. (Thomas J.)

Committee Member(s)

James, William Joseph
Leighly, Hollis P., 1923-2004
Wolf, Robert V., 1929-1999

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Metallurgical Engineering

Publisher

University of Missouri at Rolla

Publication Date

1966

Pagination

vii, 63 pages

Note about bibliography

Includes bibliographical references (page 51).

Rights

© 1966 Dennis George Dreyer, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Spinel -- Thermal propertiesZinc oxideFerric oxideMagnetite

Thesis Number

T 1900

Print OCLC #

5976850

Electronic OCLC #

874575709

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Metallurgy Commons

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