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Nachwuchsgruppe / Junior Research Group

Nanokristalle (01.02.2005-28.02.2006)

Principal Investigator

Summary

The synthesis of nanoparticles with control over particle size, shape, and crystalline structure has been one of the main objectives in nanochemistry, and yet, this is only the beginning towards the use of these materials in nanotechnology. In a next step, these nanoparticle building blocks have to be arranged into well-defined ensembles and superstructures leading to novel and unique properties that are not found in the individual components.

One of the most promising strategies for the fabrication of hierarchical structures is the use of self-assembly processes. In this context, the crucial step is the proper design of the individual components that organize themselves into desired patterns and functions. In most cases, self-assembly requires that the building units are mobile and therefore, it takes place in fluid phases or on smooth surfaces. There is no doubt that adequately tailored surface properties are the fundamental parameter in the design of novel nanobuilding blocks. The surface properties determine the interactions among the components, as well as the solubility and agglomeration behaviour in different solvents, and, thus, decide whether individual nanoparticles are suitable as nanobuilding blocks for the design of nanocomposites or for self-organizing nano devices.

The long term research goal is to develop general concepts for the fabrication of complex architectures, made up of nanocrystalline components that are hierarchically ordered by specific interactions between the nanoparticle building blocks. At the heart of this research is the high scientific and technological interest in general methodologies that make it possible to reproducibly synthesize and process metal oxide nanoparticles into 1-, 2- and 3-dimensional nanostructures over "all" length scales.

We are focussing on three main objectives:

(1) Synthesis of crystalline metal oxide nanoparticles with appropriate surface functionality,

(2) Assembly of these nanoscale building blocks into hierarchically organized superstructures and

(3) Implementation of the expertise gained to fabricate nanodevices.

We are synthesizing oxidic nanoparticles with good control over particle size, shape and crystallinity. This means that the particles are highly crystalline, uniform in shape, and exhibit a small particle size distribution. Furthermore, the surface of the particles will be functionalized with coordinating ligands, mainly by in-situ functionalization during the particle synthesis. Since the potential applications of oxidic nanostructures are mainly expected in the fields of electrochemistry, electronics, sensing and catalysis, the nanobuilding blocks have to be chosen accordingly. Especially perovskites (BaTiO3 and Pb(Zr,Ti)O3,...), conducting oxides (ZnO, SnO2, In2O3,...) and oxides that were made conducting by the incorporation of dopants and defects (TiO2, V2O5, ZrO2, Nb2O5, Ta2O5, WO3, MoO3,....) are promising precursor particles. The assembly of the nanoparticle building blocks into hierarchically ordered structures is performed by self-assembly of nanoparticles with specifically functionalized crystal surfaces. This concept is based on the adsorption of polydentate ligands to the surface of the nanoparticles in a crystallographically selective manner leading to differentially functionalized crystal faces. The surface functionalization controls the solubility as well as the assembly behaviour and allows the controlled fabrication of highly complex architectures.

Coworkers

  • Guylhaine Clavel (PhD student)
  • Mohamed Karmaoui (PhD student)
  • Ankush Mane (PhD student)

 

(letzte Änderung: 30.07.2014, 09:32 Uhr)