Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Applied Physics | en_US |
| dc.contributor.advisor | Zhao, Jiong (AP) | en_US |
| dc.creator | Wong, Lok Wing | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/13775 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Visualizing atoms and electrons for structure-property relationship by transmission electron microscopy | en_US |
| dcterms.abstract | Beyond the discovery of extraordinary properties and potential next-generation applications of low-dimensional carbon family: fullerene, carbon nanotube, and graphene, there are abundant low-dimensional materials are tremendously investigated to reproduce the success of the low-dimensional carbon family. The smaller and better characteristics provide the opportunities to fabrications of high-performance devices. However, there are still a lot of mysteries of the emerged low-dimensional materials, for example, large scale and controllable synthesis, exceptional properties (for example, super-plasticity), and the fundamental physical and chemical questions (for instance, the bonding, and their accurate atomic structure). | en_US |
| dcterms.abstract | In order to unveil the mysteries, atomic structures and nanomanipulations are needed to explore the full pictures of structure-property relationships. Transmission electron microscopy provides the opportunity to study to the low-dimensional materials in atomic scale. Although transmission electron microscopy is a powerful instrument, the experiments and data analysis are difficult, especially for the advanced techniques, like 4D-STEM. Thus, the appropriate technique is chosen to study and analyze the specimen is the key. Combining with other techniques and instruments, the preliminary checks of specimens can be done before implementing transmission electron microscopy. | en_US |
| dcterms.abstract | In this thesis, only ex situ atomic scale and in situ micro scale experiments have been conducted to study the growth kinetics as well as intermediate species of synthesis, exceptional plasticity of 2D materials, and quantitative dDPC-STEM for MOFs and atomic columns by using transmission electron microscopy. The first 2 topics mainly use the conventional STEM techniques with the specific specimen preparation methods to show the intermediate structures to analyze the whole picture of mechanisms. First, the critical intermediate species octahedral Re6Se8 was found that reduced by hydrogen from the precursors in atmosphere, that is the key to the nucleation and epitaxial growth. Second, the exceptional plasticity of InSe has been comprehensively investigated by microscopic view and macroscopic view. The overlooked phase transition from 2H to 3R increases the gliding barrier significantly as high as 24.07%, that ceases the micro-crack propagation surrounded. Hence, the excellent plasticity of InSe is caused by the synergetic effect of strain relaxation, phase transition, strain accumulation, and structural strengthening. Finally, statistical measurements have been conducted to minimize the low SNR problem of dDPC-STEM, that provide not only the coordination number, but also the lower energy site, that provides the insight to the structural engineering of metal-organic frameworks. | en_US |
| dcterms.abstract | In the near future, in situ atomic scale studies will be applied to unveil more mechanism of the low-dimensional materials' properties. It depends on the complete installation of a new transmission electron microscopy due to the delay caused by COVID-19 pandemic. On the other hand, the general rule of brittle-ductile materials will be investigated by either computational based or experimental based methods. Besides, the undiscovered dDPC-STEM will be further studied from the big data. | en_US |
| dcterms.extent | xxxii, 125 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2023 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.accessRights | open access | en_US |
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