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dc.contributor.authorSmith, Gary Lynn.
dc.creatorSmith, Gary Lynn.en_US
dc.date.accessioned2011-10-31T17:59:54Z
dc.date.available2011-10-31T17:59:54Z
dc.date.issued1993en_US
dc.identifier.urihttp://hdl.handle.net/10150/186142
dc.description.abstractThe magnitude and temperature dependence of both the nucleation and crystal growth rates in lithium diborate glass were determined in the temperature range, 490 to 520°C. Comparison of the nucleation rates predicted by Classical Nucleation Theory and those found experimentally shows that the predicted classical nucleation rates are about 95 orders of magnitude smaller than the experimentally determined values. In addition, Classical Nucleation Theory does not predict the temperature dependence found experimentally. Comparison is also made with silicate glass systems which have been shown to exhibit homogeneous nucleation. Crystal nucleation in the lithium diborate glass almost certainly proceeds by a homogeneous mechanism. Comparisons are made between experimentally obtained values of the crystal growth rate in lithium diborate glass and those computed using surface nucleated crystal growth theory. Although the temperature dependence of the experimental growth rates at large undercoolings appears to be described well by the latter model, the computed values of the growth rates are about 60 orders of magnitude too small. Using a temperature dependent surface tension (obtained from fitting crystal nucleation data) in the surface nucleated crystal growth model partially reduces the discrepancy between the experimental and calculated magnitudes of the growth rate, but produces an incorrect prediction for the temperature dependence of the growth rate.
dc.language.isoenen_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.subjectDissertations, Academic.en_US
dc.subjectMaterials science.en_US
dc.titleNucleation and crystallization of lithium diborate glass.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.contributor.chairWeinberg, Michael C.en_US
dc.identifier.oclc715378796en_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.contributor.committeememberNeilson, George F.en_US
dc.contributor.committeememberZelinski, Brian J.J.en_US
dc.contributor.committeememberDrake, Michael J.en_US
dc.contributor.committeememberMelosh, H. Jayen_US
dc.identifier.proquest9322642en_US
thesis.degree.disciplineMaterials Science and Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.namePh.D.en_US
dc.description.noteThis item was digitized from a paper original and/or a microfilm copy. If you need higher-resolution images for any content in this item, please contact us at repository@u.library.arizona.edu.
dc.description.admin-noteOriginal file replaced with corrected file September 2023.
refterms.dateFOA2018-05-25T21:12:58Z
html.description.abstractThe magnitude and temperature dependence of both the nucleation and crystal growth rates in lithium diborate glass were determined in the temperature range, 490 to 520°C. Comparison of the nucleation rates predicted by Classical Nucleation Theory and those found experimentally shows that the predicted classical nucleation rates are about 95 orders of magnitude smaller than the experimentally determined values. In addition, Classical Nucleation Theory does not predict the temperature dependence found experimentally. Comparison is also made with silicate glass systems which have been shown to exhibit homogeneous nucleation. Crystal nucleation in the lithium diborate glass almost certainly proceeds by a homogeneous mechanism. Comparisons are made between experimentally obtained values of the crystal growth rate in lithium diborate glass and those computed using surface nucleated crystal growth theory. Although the temperature dependence of the experimental growth rates at large undercoolings appears to be described well by the latter model, the computed values of the growth rates are about 60 orders of magnitude too small. Using a temperature dependent surface tension (obtained from fitting crystal nucleation data) in the surface nucleated crystal growth model partially reduces the discrepancy between the experimental and calculated magnitudes of the growth rate, but produces an incorrect prediction for the temperature dependence of the growth rate.


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