Research » (NGR)
∴ IN » Nanokristalle (01.02.2005-28.02.2006)
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)
