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dc.contributor.advisorBowles, Richarden_US
dc.creatorAsuquo, Cletusen_US
dc.date.accessioned2009-12-15T17:19:58Zen_US
dc.date.accessioned2013-01-04T05:10:37Z
dc.date.available2012-02-02T08:00:00Zen_US
dc.date.available2013-01-04T05:10:37Z
dc.date.created2009en_US
dc.date.issued2009en_US
dc.date.submitted2009en_US
dc.identifier.urihttp://hdl.handle.net/10388/etd-12152009-171958en_US
dc.description.abstractStudies of nucleation in freezing nanoparticles usually assume that the embryo of the solid phase is completely wet by the liquid and forms in the core of the droplet. However, recent experiments and computer simulations have suggested that some nanoparticles start nucleating at the liquid-vapor interface of the drop in a pseudoheterogeneous process. The goal of the present work is to propose phenomenological models suitable for the study of surface nucleation in nanoparticle systems that can be used to understand the contributions of the various surface phenomena, such as surface and line tensions, to the nucleation barrier. The nucleation barrier for the freezing of a 276 atom gold cluster is calculated using Monte Carlo simulation techniques while previous simulation studies of a 456 atom gold cluster are extended in order to find the probability that the embryo forms in the surface or core of the nanoparticle. These calculations confirm that the crystal embryo forms at the liquid-vapor interface. Geometric studies measuring the liquid-solid and solid-vapor surface areas of the embryo suggest that it changes shape as it becomes larger and grows in towards the core of the droplet. Three phenomenological models that are based on the capillarity approximation and can account for surface nucleation are proposed. These models highlight the importance of accounting for the surface curvature contributions related to the Tolman length and the presence of the three phase contact line in calculating the nucleation free energy barrier. In some cases, the models are able to reproduce the qualitative properties of the free energy barriers obtain from simulation but numerical fits of the models generally result in estimates of the solid-liquid surface tension that are lower than the values expected on the basis of partial wetting in the bulk. Finally, a semi-phenomenological model approach to nucleation is proposed where the usual phenomenological expression for the free energy barrier is retained, but where the geometric prefactors are obtained from molecular simulation of the embryo. This method is applied to nucleation in the gold cluster and to the freezing of a bulk Lennard-Jones liquid.en_US
dc.language.isoen_USen_US
dc.subjectSurface tensionen_US
dc.subjectSurface nucleationen_US
dc.subjectNucleation barrieren_US
dc.subjectHomogeneous nucleationen_US
dc.subjectPhenomenological modelsen_US
dc.titlePhenomenological and semi-phenomenological models of nano-particles freezingen_US
thesis.degree.departmentChemistryen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.grantorUniversity of Saskatchewanen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Science (M.Sc.)en_US
dc.type.materialtexten_US
dc.type.genreThesisen_US
dc.contributor.committeeMemberBradley, Michaelen_US
dc.contributor.committeeMemberBurgess, Ianen_US
dc.contributor.committeeMemberBaranski, Andrzejen_US


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