This study was undertaken to gain a greater understanding of the growth mechanism of carbon nanoclusters. A set of carbon nanocluster samples prepared by three different methods and under different conditions was characterized with respect to morphology, structure, composition, and related properties. Electron microscopy characterization techniques were used to identify these features. The carbon nanoclusters prepared by conventional arc discharge, modified arc discharge, and catalytic CO disproportionation appear quite different on the surface, but have features in common that this study emphasizes. For the understanding of the growth mechanisms of carbon nanoclusters of different morphologies, the dependence of growth features on the major processing parameters--carbon supply and carbon activity, reaction temperature, gas type and partial pressure, composition and materials involved--was interpreted systematically in a comparative manner. For the encapsulation of foreign materials into carbon cages, the ratio of the supply of carbon and encapsulants, the dimensions and configurations of the electrodes, the flow of a buffer gas across the carbon source, the nature and surface area of materials to be encapsulated or acting as catalyst were recognized as the basic components of a process that lead to properties of as-made materials such as the size distribution of the clusters, the degree of the carbonization of the encapsulants, and the predominant presence of certain morphologies. Regarding the comparison of the structural stability of different morphologies, the results of the post deposition treatments such as elevated high temperature annealing, nitric acid erosion, and electron beam bombardment provide further insight into the properties of this novel family of materials. Operating in certain domains of the parameter space, carbon-coated ferromagnetic nanoparticles, single-walled nanotubes, cylindrical multi-walled nanotubes, and conical fish-bone filaments were produced and comparatively characterized. A tentative discussion with the aim of confirming, expanding or modifying some growth models that have emerged from the work of the past was given in this dissertation. It is expected that this broad-based comparative study will advance the understanding of the growth mechanism to a point where some of the technological promise of the carbon nanoclusters may be realized.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/282358 |
| Date | January 1997 |
| Creators | Jiao, Jun, 1957- |
| Contributors | Seraphin, Supapan |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Dissertation-Reproduction (electronic) |
| 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. |
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