Doctoral theses
Current Record: 2022 of 2491
|
Identifier |
000376813 |
Title |
Σύνθεση και χαρακτηρισμός υβριδικών δομών νανοκρυστάλλων με ρυθμιζόμενες ιδιότητες |
Alternative Title |
Synthesis and characterization of hybrid nanocrystal structures with tailored properties |
Author
|
Κωστοπούλου, Αθανασία Ιωάννης
|
Thesis advisor
|
Λαππας, Αλέξανδρος
|
Reviewer
|
Τρικαλίτης, Παντελής
Κουτσολέλος, Αθανάσιος
|
Abstract |
Considerable progress in the synthesis of colloidal inorganic nanocrystas has allowed their exploitation in different applications, ranging from electronics to biomedicine. A significant advancement in the syntheses of nanocrystals entails the capacity to afford not only single- but multi- material hybrids. This thesis presents the development of colloidal chemistry protocols and the characterization of a self-assembled secondary structure (nanocluster) and a hybrid multimaterial heterostructure.
The nanoclusters involve a low cytotoxivity assembly of small γ-Fe2O3 nanocrystals (NCs). The colloidal assemblies are ferrimagnetic in aqueous dispersions and composed of crystallographically aligned NCs. The colloid of nanoclusters operates as a tunable photonic crystal under a moderate magnetic field. Their potential in biomedical diagnosis (MRI) and therapy (magnetic hyperthermia) is shown. Due to their tailored magneto-structural characteristics, the intra-cluster magnetic material volume fraction is raised, in turn producing a remarkable improvement of the transverse 1H-NMR relaxivity (4-5 times higher than that of the commercial contrast agent Endorem®) and a much higher Specific Loss Power is attained than that of other rival nanostructures.
The hybrid heterostructure consists of ZnO nanorods uniformly covered by size-tunable Fe@FexOy core-shell nanocrystals. The bi-functional [cf. with near band-edge (NBE) UV fluorescence and ferromagnetism at 300 K] nanomaterial is characterized by an extended surface coverage with small Fe@FexOy nanodomains, where the interfacial coupling across the Fe-core and FexOy-shell generates exchange-bias, mediated by frozen interfacial spins. In the case of a lower coverage density by larger Fe@FexOy domains, the operating Kirkendall effect between the core and the shell suppresses the exchange coupling anisotropy. Importantly, the interfacial interactions between ZnO-Fe@FexOy scale with the degree of surface coverage and a strain-induced blue-shift of the NBE is observed.
|
Language |
Greek |
Subject |
Colloidal chemistry |
|
Contrast agent |
|
Core-shell structure |
|
Exchange bias |
|
Hybrid heterostructure |
|
Iron oxide |
|
Magnetic hyperthermia |
|
Magnetic nanocrystals |
|
Magnetic resonance imaging |
|
Nanocluster |
|
Απεικόνιση μαγνητικού συντονισμού |
|
Δομή πυρήνα-κελύφους |
|
Κολλοειδής χημεία |
|
Μαγνητική υπερθερμία |
|
Μαγνητικοί νανοκρύσταλλοι |
|
Νανοσυσσωμάτωμα |
|
Οξείδιο του σιδήρου |
|
Πόλωση λόγω ανταλλαγής |
|
Σκιαγραφικό μέσο |
|
Υβριδική ετεροδομή |
Issue date |
2012-11-23 |
Collection
|
School/Department--School of Sciences and Engineering--Department of Chemistry--Doctoral theses
|
|
Type of Work--Doctoral theses
|
Permanent Link |
https://elocus.lib.uoc.gr//dlib/a/e/9/metadata-dlib-1353667278-195381-15926.tkl
|
Views |
580 |