EQUILIBRIUM PROPERTIES OF SOME SILICATE MATERIALS: A THEORETICAL STUDY (MAGNESIUM OXIDE, ALUMINUM OXIDE, SILICON DIOXIDE).

Persistent Link:
http://hdl.handle.net/10150/184514
Title:
EQUILIBRIUM PROPERTIES OF SOME SILICATE MATERIALS: A THEORETICAL STUDY (MAGNESIUM OXIDE, ALUMINUM OXIDE, SILICON DIOXIDE).
Author:
HOSTETLER, CHARLES JAMES.
Issue Date:
1982
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Equilibrium properties of the MgO-Al₂O₃-SiO₂ (MAS) system are modeled using techniques from statistical and quantum mechanics. The fundamental structural units in this model are the closed shell ions: Mg²⁺, Al³⁺, Si⁴⁺, and O²⁻. The equilibrium properties of the MAS system are determined by the interactions among these ions and by the environment (i.e. temperature and pressure). The interactions are modeled using coulombic, dispersion, and repulsive forces. Two parameters appearing in the repulsive terms for each cation-oxygen interaction are fitted from properties of quartz, corundum, and periclase crystals. The effects of the environment on the liquid and solid compositions found in this system are calculated using a Monte Carlo technique involving the generation of a Markov chain of configurations; each configuration being a "snapshot" of the particles in the liquid or solid material being studied. The properties of the material are derived from averaging appropriate quantities over all the configurations. Enthalpies of formation, heat capacities, and volumes of seven compositions in the MAS system have been calculated using this method. All are within three percent of the corresponding experimental values. Radial distribution functions for these runs show the competition among the cations for the common anion, oxygen, under charge and mass balance constraints. The electronic structure of several molecular clusters in the MAS system are examined using ab initio linear combinations of atomic orbitals (LCAO) techniques. The assumptions used in LCAO calculations are examined and a small, balanced basis set for the MAS system is presented. The Mg-, Al-, and Si-O interactions are all found to be highly ionic using this basic set. Using a first principles technique, the two body effective pair potentials assumed for the Monte Carlo calculations were shown to be physically reasonable.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Aluminum-magnesium-silicon alloys.; Igneous rocks.; Rock mechanics.; Silicates.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Planetary Sciences; Graduate College
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleEQUILIBRIUM PROPERTIES OF SOME SILICATE MATERIALS: A THEORETICAL STUDY (MAGNESIUM OXIDE, ALUMINUM OXIDE, SILICON DIOXIDE).en_US
dc.creatorHOSTETLER, CHARLES JAMES.en_US
dc.contributor.authorHOSTETLER, CHARLES JAMES.en_US
dc.date.issued1982en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractEquilibrium properties of the MgO-Al₂O₃-SiO₂ (MAS) system are modeled using techniques from statistical and quantum mechanics. The fundamental structural units in this model are the closed shell ions: Mg²⁺, Al³⁺, Si⁴⁺, and O²⁻. The equilibrium properties of the MAS system are determined by the interactions among these ions and by the environment (i.e. temperature and pressure). The interactions are modeled using coulombic, dispersion, and repulsive forces. Two parameters appearing in the repulsive terms for each cation-oxygen interaction are fitted from properties of quartz, corundum, and periclase crystals. The effects of the environment on the liquid and solid compositions found in this system are calculated using a Monte Carlo technique involving the generation of a Markov chain of configurations; each configuration being a "snapshot" of the particles in the liquid or solid material being studied. The properties of the material are derived from averaging appropriate quantities over all the configurations. Enthalpies of formation, heat capacities, and volumes of seven compositions in the MAS system have been calculated using this method. All are within three percent of the corresponding experimental values. Radial distribution functions for these runs show the competition among the cations for the common anion, oxygen, under charge and mass balance constraints. The electronic structure of several molecular clusters in the MAS system are examined using ab initio linear combinations of atomic orbitals (LCAO) techniques. The assumptions used in LCAO calculations are examined and a small, balanced basis set for the MAS system is presented. The Mg-, Al-, and Si-O interactions are all found to be highly ionic using this basic set. Using a first principles technique, the two body effective pair potentials assumed for the Monte Carlo calculations were shown to be physically reasonable.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectAluminum-magnesium-silicon alloys.en_US
dc.subjectIgneous rocks.en_US
dc.subjectRock mechanics.en_US
dc.subjectSilicates.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePlanetary Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.identifier.proquest8227355en_US
dc.identifier.oclc682952405en_US
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