The exceptional properties of nanocrystals (NCs) are strongly influenced by many different characteristics, such as their size and shape, but also by characteristics on the atomic scale, such as their crystal structure, their surface structure, as well as by potential microstructure defects. While the size and shape of NCs are frequently determined in a statistical manner, atomic-scale characteristics are usually quantified only for a small number of individual NCs and thus with limited statistical relevance. Within this work, a characterization workflow was established that is capable of determining relevant NC characteristics simultaneously in a sufficiently detailed and statistically relevant manner. The workflow is based on transmission electron microscopy, networked by a correlative multiscale approach that combines atomic-scale information on NCs obtained from high-resolution imaging with statistical information on NCs obtained from low-resolution imaging, assisted by a semi-automatic segmentation routine. The approach is complemented by other characterization techniques, such as X-ray diffraction, UV-vis spectroscopy, dynamic light scattering, or alternating gradient magnetometry. The general applicability of the developed workflow is illustrated on several examples, i.e., on the classification of Au NCs with different structures, on the statistical determination of the facet configurations of Au nanorods, on the study of the hierarchical structure of multi-core iron oxide nanoflowers and its influence on their magnetic properties, and on the evaluation of the interplay between size, morphology, microstructure defects, and optoelectronic properties of CdSe NCs.:List of abbreviations and symbols
1 Introduction
1.1 Types of nanocrystals
1.2 Characterization of nanocrystals
1.3 Motivation and outline of this thesis
2 Materials and methods
2.1 Nanocrystal synthesis
2.1.1 Au nanocrystals
2.1.2 Au nanorods
2.1.3 Multi-core iron oxide nanoparticles
2.1.4 CdSe nanocrystals
2.2 Nanocrystal characterization
2.2.1 Transmission electron microscopy
2.2.2 X-ray diffraction
2.2.3 UV-vis spectroscopy
2.2.3.1 Au nanocrystals
2.2.3.2 Au nanorods
2.2.3.3 CdSe nanocrystals
2.2.4 Dynamic light scattering
2.2.5 Alternating gradient magnetometry
2.3 Methodical development
2.3.1 Correlative multiscale approach – Statistical information beyond
size and shape
2.3.2 Semi-automatic segmentation routine
3 Classification of Au nanocrystals with comparable size but different
morphology and defect structure
3.1 Introduction
3.1.1 Morphologies and structures of Au nanocrystals
3.1.2 Localized surface plasmon resonance of Au nanocrystals
3.1.3 Motivation and outline
3.2 Results
3.2.1 Microstructural characteristics of the Au nanocrystals
3.2.2 Insufficiency of two-dimensional size and shape for an
unambiguous classification of the Au nanocrystals
3.2.3 Statistical classification of the Au nanocrystals
3.2.4 Advantage of a multidimensional characterization of the Au
nanocrystals
3.2.5 Estimation of the density of planar defects in the Au nanoplates
3.3 Discussion
3.4 Conclusions
4 Statistical determination of the facet configurations of Au nanorods
4.1 Introduction
4.1.1 Growth mechanism and facet formation of Au nanorods
4.1.2 Localized surface plasmon resonance of Au nanorods
4.1.3 Catalytic activity of Au nanorods
4.1.4 Motivation and outline
4.2 Results
4.2.1 Statistical determination of the size and shape of the Au nanorods
4.2.2 Microstructural characteristics and facet configurations of the Au
nanorods
4.2.3 Statistical determination of the facet configurations of the Au
nanorods
4.3 Discussion
4.4 Conclusions
5 Influence of the hierarchical architecture of multi-core iron oxide
nanoflowers on their magnetic properties
5.1 Introduction
5.1.1 Phase composition and phase distribution in iron oxide
nanoparticles
5.1.2 Magnetic properties of iron oxide nanoparticles
5.1.3 Mono-core vs. multi-core iron oxide nanoparticles
5.1.4 Motivation and outline
5.2 Results
5.2.1 Phase composition, vacancy ordering, and antiphase boundaries
5.2.2 Arrangement and coherence of individual cores within the iron
oxide nanoflowers
5.2.3 Statistical determination of particle, core, and shell size
5.2.4 Influence of the coherence of the cores on the magnetic
properties
5.3 Discussion
5.4 Conclusions
6 Interplay between size, morphology, microstructure defects, and
optoelectronic properties of CdSe nanocrystals
6.1 Introduction
6.1.1 Polymorphism in CdSe nanocrystals
6.1.2 Optoelectronic properties of CdSe nanocrystals
6.1.3 Nucleation, growth, and coarsening of CdSe nanocrystals
6.1.4 Motivation and outline
6.2 Results
6.2.1 Influence of the synthesis temperature on the optoelectronic
properties of the CdSe nanocrystals
6.2.2 Microstructural characteristics of the CdSe nanocrystals
6.2.3 Statistical determination of size, shape, and amount of oriented
attachment of the CdSe nanocrystals
6.3 Discussion
6.4 Conclusions
7 Summary and outlook
References
Publications
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:87626 |
| Date | 21 December 2023 |
| Creators | Neumann, Stefan |
| Contributors | Rafaja, David, Cieslar, Miroslav, Technische Universität Bergakademie Freiberg |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 10.1039/D0CE00312C, 10.1093/micmic/ozac027, 10.1038/s41598-023-31294-4 |
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