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miami997447312.pdf (723.21 KB)
ETD Abstract Container
Abstract Header
The use of optimization methods-and thermodynamic implications-in mineraology
Author Info
Foley, Jeffrey A.
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=miami997447312
Abstract Details
Year and Degree
2001, Doctor of Philosophy, Miami University, Geology and Environmental Earth Science.
Abstract
This research has been bound together by one common theme: optimization. Chapters one and two are examples of traditional crystal structure refinements. Chapter three explains the site assign problem and documents a new approach to the problem. Chapter four extends the method to high temperaturese; chapter five extracts the thermodynamic information found in the site occupancies. The appendix is a user's manual for OCCQP. In chapter one the structure and formula of brackebuschite was redefined. Also, the crystal chemistry of the d 4 Mn 3+ ion in oxygen-based minerals is reviewed. Chapter two presents the refinement of redledgeite. It and its synthetic equivalent are important as a solid-state repository for toxic heavy-metal waste. With chapter three, the traditional methods of determining site occupancies in minerals come in to question. The approach is based on crystal-structure data and chemical analyses of the compound, without making prior assumptions. This method provides the flexibility to evaluate trade-offs inherent in assigning occupancies on the basis of a single criterion. Multiple criteria may be used and their relative importance adjusted interactively. The optimizations yield excellent results. Chapter four builds upon the foundation established in chapter three. This chapter is a reexamination of the cation partitioning of the same spinel used in chapter three. This method led to strikingly different results from the authors of the original study, supporting the general view that spinel undergoes a lambda transition at ~1000K. Chapter five extends the thermodynamic formulations for spinel. Most thermodynamic studies of spinels have focused on simple end-member compositions, meaning only two cations—at most—are distributed among the octahedral and tetrahedral sites. This chapter considers a 2-3 spinel having three cation species and vacancies. The standard thermodynamic technique is to consider migration of cations between octahedral and tetrahedral positions as reactions. The stability coefficient D K gives the changes in Gibbs free energy of distribution, and statistical mechanics yields the entropy of distribution.
Committee
John Hughes (Advisor)
Pages
124 p.
Subject Headings
Geology
Keywords
optimization
;
thermodynamic
;
mineralogy
;
geology
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Citations
Foley, J. A. (2001).
The use of optimization methods-and thermodynamic implications-in mineraology
[Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami997447312
APA Style (7th edition)
Foley, Jeffrey.
The use of optimization methods-and thermodynamic implications-in mineraology.
2001. Miami University, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=miami997447312.
MLA Style (8th edition)
Foley, Jeffrey. "The use of optimization methods-and thermodynamic implications-in mineraology." Doctoral dissertation, Miami University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=miami997447312
Chicago Manual of Style (17th edition)
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Document number:
miami997447312
Download Count:
2,230
Copyright Info
© 2001, all rights reserved.
This open access ETD is published by Miami University and OhioLINK.