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A Theory of Nanoparticle Growth and a Theory of Thin Film Nucleation
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | A Theory of Nanoparticle Growth and a Theory of Thin Film Nucleation. |
| 개인저자 | Mastandrea, James P. |
| 단체저자명 | University of California, Berkeley. Materials Science & Engineering. |
| 발행사항 | [S.l.]: University of California, Berkeley., 2017. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2017. |
| 형태사항 | 49 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-04B. Dissertation Abstract International |
| ISBN | 9781085775922 |
| 학위논문주기 | Thesis (Ph.D.)--University of California, Berkeley, 2017. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Advisor: Chrzan, Daryl C. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | This dissertation is divided into two parts. The first will discuss a theory that was identified to narrow the size distribution of nanoparticles grown via ion beam synthesis (IBS). Specifically, a simple mathematical argument explains a processing route for the ion beam synthesis of nanoclusters with a narrowed size distribution. The key idea is that growth conditions for which the average nanocluster size is increasing rapidly can lead to narrowed size distributions. Modeling candidate processes using a self-consistent, mean-field theory shows that normalized nanocluster size distributions with full-width at half-maximum of 17% of the average can be attained.The second part presents a theory for nucleation in confined high-aspect ratio thin films. Specifically, classical nucleation theory is used to consider the solidification of a melt confined between two planar surfaces. The critical nuclei shapes and the associated nucleation energy barriers are computed as a function of the thickness of the film, and the film's relevant bulk and interface energies. The analysis is then repeated for the melting transition, and expressions for the depression and elevation of the melting temperature are found. A nucleus morphology diagram is constructed. This diagram presents the lowest energy morphology of the nuclei, as well as melting points, as a function of the system parameters. Using the nucleus morphology diagram, experimental and system parameters that allow for the desired nucleation behavior can be identified. Furthermore, the nucleus morphology diagram illustrates a region of parameter space where the film is predicted to solidify above its thermodynamic bulk melting temperature, a behavior termed presolidification. The theory is used to predict the temperature at which nucleation of the solid phase and liquid phase are expected for Ge between two glass substrates. Furthermore, a possible route for controlling the orientation of the film is identified as confinement of the film can lead to a large range of solid phase nucleation temperatures, which are a function of the system's interfacial free energies. By controlling the growth temperature, certain orientations may not be able to nucleate thereby reducing the possible number of orientations within a film. |
| 일반주제명 | Nanoscience. Materials science. |
| 언어 | 영어 |
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: 이 자료의 원문은 한국교육학술정보원에서 제공합니다. |
