Synthesis of advanced inorganic colloidal nanocrystals
Colloidal nanocrystals are crystalline materials of nanometer size which are colloidally suspended in a solution. Typical nanocrystals are made of few tens to some thousands atoms. Because of their small size they exhibit properties different to the conventional bulk materials. In the nanosize regim...
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|Zusammenfassung:||Colloidal nanocrystals are crystalline materials of nanometer size which are colloidally suspended in a solution. Typical nanocrystals are made of few tens to some thousands atoms. Because of their small size they exhibit properties different to the conventional bulk materials. In the nanosize regime, in fact, it is not just the composition which determines the properties of a material but also its size and shape. The possibility to control these parameters allows the fabrications of nanocrystals whose properties can be exploited in several fields such as electronics, diagnostics, catalysis and optoelectronics. In this dissertation we will focus on semiconductive nanocrystals with particular attention to a new synthesis process which allows us to have a better control on the size and thus the properties. In particular we show that for small nanocrystals the growth is not continuous. Instead the nanocrystals grow discretely, from one stable configuration to the next bigger stable configuration. The possible stable configurations are termed "magic size clusters". For bigger particles growth is continuous. We report the generalization of the process to grow magic size clusters for several semiconductor materials. Also an application of magic size clusters of CdSe for the fabrication of light emitters is reported. The characterisation and application of particular semiconductive nanomaterials presented in this work will led us to the synthesis of more complex nanostructures such as core@shell nanomaterials and semiconductive-magnetic dimers. We demonstrate in particular the growth of II/VI semiconductor materials on top of FePt nanocrystals. Thus dimeric nanocrystals with a magnetic FePt domain and a II/VI domain are obtained. In these systems it is possible to combine together properties of the different materials in order to fabricate nanoparticles presenting as well a magnetic as a semiconductive domain.|