Nanosciences

Nanotechnology research is being conducted in numerous interdisciplinary, transdisciplinary and international collaborations at the University of Duisburg-Essen and has produced numerous publications and patents. Funding agencies include the European Union, the German Federation of Industrial Research Associations (AiF), the state of North Rhine-Westphalia, and the German Research Foundation (DFG). The DFG is currently supporting three Collaborative Research Centres, SFB 445 "Nanoparticles from the Gasphase", SFB 491 "Magnetic Heterostructures", and SFB 616 "Energy Dissipation at Surfaces", and a Research Training Group on "Nanotronics" (GK 1240). CeNIDE is also working on processes to enable the fabrication of nanomaterials in larger quantities. Worldwide, there are only a few research facilities with similar capabilities, and CeNIDE is the only one in Europe.
Investigation of the health effects of nanoparticles is of great importance for the development of sustainable nanotechnology. CeNIDE is therefore also researching the potentially adverse effects of nanoparticles. Within the "Nanocare" project concluded in June 2009, Dr. Thomas Kuhlbusch of the Institute of Energy and Environmental Technology (IUTA e.V.) coordinated a research consortium investigating the health effects of industrially manufactured nanoparticles. Up to 2013, the EU-funded follow-up project, "Nanodevice", will develop portable measurement equipment to monitor personal exposure to nanoparticles at the workplace. One of the coordinators of this project is the aerosol researcher Professor Heinz Fissan.
The DFG Priority Programme SPP 1313, "Biological Responses to Nanoscale Particles", was set up in 2008 and is directed by Professor Reinhard Zellner of the Faculty of Chemistry. This interdisciplinary programme is investigating, over a six-year period, the fundamental interactions of nanoparticles with biological molecules, systems and cells.
The experimental facilities developed on the basis of research results obtained within Collaborative Research Centre SFB 445 have attracted international attention. This equipment has enabled large-scale production of nanomaterials. The specific properties of nanoparticles only develop when the size of the material is decreased to the nanoscale. More specifically, the smallest fraction of a material reacts differently to outside influences than the bulk material. When the nanoparticles are again reassembled in a macroscopic entity, special care must be taken that their unique electrical and mechanical qualities are preserved. Mastering this process is essential for application; only when materials can be produced in large quantities is it possible to develop the subsequent stages of processing up to product level.
One area of application for which nanotechnology offers a great deal of potential is energy technology. Established methods of energy conversion and energy storage can be organised much more efficiently with the help of nanomaterials. In this context, CeNIDE members have been successful in the "NanoMikro+Werkstoffe.NRW" competition run by the Ministry for Innovation, Science, Research and Technology (MIWFT). The two projects are the "NanoEnergieTechnikZentrum" (NETZ) and "Halbleiter-Nanodrähte für Solarzellen und Leuchtdioden (NaSoL)", which together will receive 14.2 million euros in funding for the next three years. The goal of NETZ is to develop a technology platform to provide the materials for applications relating to energy technology. Under the direction of Professor Christof Schulz from the Faculty of Engineering, researchers are concentrating on the development of new materials for fuel cells, lithium ion batteries, energy-related catalysis, photovoltaics, and thermoelectrics. In the NaSoL project, Professor Franz-Josef Tegude, a specialist in semiconductor technology, is coordinating research on the development of solar cells and light-emitting diodes on nanowires.
CeNIDE researchers are also playing a significant role in "Nanostructured Thermoelectrics", another DFG Priority Programme (SPP 1386) dedicated to thermoelectrics. This is an example of an excellent network of interdisciplinary interaction within CeNIDE: in this project, Dr. Gabi Schierning (Electrical Engineering), Professor Dietrich Wolf (Theoretical Physics) and Dr. Hartmut Wiggers (Mechanical and Process Engineering) are working together on the development of more efficient and ecological materials for thermoelectric applications. Professor Peter Kratzer, a theoretical physicist, is also working on another area of the SPP entitled "Theory, Model Systems and Controlled Synthesis".
What happens when energy meets a surface? This is a question the physicists and chemists of Collaborative Research Centre SFB 616, "Energy Dissipation at Surfaces", are currently pursuing. In their investigations the researchers apply ultra-short laser pulses to instantly liquefy or vaporise materials, or they send electrons into nanostructures and observe the reactions. They do this using microscopes which make extremely fast processes visible. Their successes include identification, in cooperation with scientists from the University of Toronto, of a completely novel melting process with bismuth. The researchers showed that it is possible to melt bismuth within 190 femtoseconds (a femtosecond is one quadrillionth of a second, or 0.000000000000001 second). This unimaginably short period describes the time during which bismuth changes from solid to liquid state by non-thermal melting. The melting process is triggered by an ultra-intensive 50 femtosecond-short laser pulse, which accelerates the atoms so quickly that the conditions for the bismuth crystal to remain in its crystalline structure are suddenly removed. The findings were published under the title of "Electronic acceleration of atomic motions and disordering in bismuth" in the noted academic journal, "Nature". The authors of the paper from the UDE are Thomas Payer, Dr. Frank-J. Meyer zu Heringdorf, and Professor Michael Horn-von Hoegen.
Nanotechnology researchers under the direction of Dr. Nils Hartmann in the Faculty of Chemistry are also working on laser technology. They have developed a method to structure the layers of phospholipids; an article on the subject was published in "Small" journal. Amongst their applications, phospholipid layers are used as model systems for membranes. Recently, such layers have been attracting increased interest as flexible biomolecular matrices for various micro and nanoscale applications, including the production of novel sensors and data storage devices. Future developments will depend to a great extent on the ability to fabricate nanostructured phospholipid layers.
Physicists working with Professor Rolf Möller, in cooperation with the University of Göttingen, have accomplished an outstanding achievement by determining how to measure Ohm's Law on the atomic scale. Ohm's Law describes the correlation between the voltage drop and electric current at constant temperature; the researchers have shown that it is possible to measure voltages over single atoms. Although this process has not yet been relevant to the development of microelectronic components, it is likely that progressive miniaturisation will make it necessary to consider the contributions made to electrical resistance atom by atom in future. The research results were published in the nanotechnology journal "Nano Letters".
The engineering group of Professor Gerd Bacher has turned a dream of many materials scientists into reality. The researchers in this group have been able to combine the benefits of the long-lasting information storage capabilities of magnetic metals with the ultrafast data processing of electronic semiconductors. For the first time, semiconductor nanoparticles have been successfully magnetised using light pulses. Tiny nanocrystals have an extremely effective magnetic field 300,000 times stronger than the earth's magnetic field, and consequently the light-induced magnetisation has very high thermal stability. The new nanomaterials should now enable researchers to develop innovative applications in information technology at room temperature. A corresponding report was published in "Science".
Applied research is taking place within the framework of a transfer project under Collaborative Research Centre SFB 445 entitled "Synthesis and integration of nanoparticles in PVD (Physical Vapor Deposition) layers for the improvement of tribological properties". Under the direction of Engineering Faculty Professor Einar Kruis, knowledge compiled in this Collaborative Research Centre will be applied in nanoparticle synthesis and nanoparticle deposition for the automotive industry. This project specifically concerns the realisation of a new coating process which allows integration of tailored nanoparticles. The new technology will permit the manufacture of customised composite PVD coating systems to improve the properties of piston rings in next-generation engines.
Another joint project with the automotive industry, headed by Professor Christian Mayer of the Faculty of Chemistry, is being conducted under the title of "Functional surfaces via inclusion of nanocapsules in metallic matrices". Professor Mayer is developing self-repairing protective layers for metal surfaces together with engineer Dr. Claudia Dos Santos from the Institute of Industrial Manufacturing and Management (IFF) at the University of Stuttgart. These films are functionally designed like human skin; the actual innovation consists in the combination of two methods, namely coating with metal ions and nanocapsules.
The interaction of small nanopyramids or "quantum dots" with a conductive contact layer - a two-dimensional electron gas - is the topic of a joint research project titled "Coupling of single quantum dots to two-dimensional systems", or "Q2D2" for short. The project is being coordinated by experimental physicist Dr. Martin Paul Geller and investigates the frontiers of charge-based memory, or flash memory. This type of memory has become increasingly small, since it needs less and less charge carriers for information storage. The project is being conducted in cooperation with the Technical University of Berlin, Lancaster University (UK) and the Technical University of Eindhoven (Netherlands). Amongst other topics, the question of whether quantum dots can be used in future memory chip applications will be clarified. The project is being financed by the European Union and four other national funding organisations.
The Institute of Energy and Environmental Technology (IUTA e.V.) has premiered a new project, the "Center for filtration research and functional surfaces" (ZF3), which originated through the "HighTech.NRW" competition. The Center is working together with regional companies to develop a new generation of functional filters which will be able, for example, to separate gases from small dust particles, intercept noxious odours and absorb poisonous substances. In order to achieve these goals, researchers plan to develop new kinds of structures (such as purifying fibres) or specifically fabricate and employ nanoparticles.