Research
The Institute of Materials Science of the Faculty of Engineering covers a wide range of topics in materials science and its applications. Functional Materials and Building Materials are the two general areas of research.
The broadest expertise exists for non metallic-inorganic functional materials and composites. Electrical and mechanical behavior are central research elements. Our functional material activities are complemented by organic electronic materials and hybrids for organic photovoltaics.
Freezing and durability of concrete are our classical civil engineering topics. For these we offer a wide range of services. Materials for thermal isolation and high temperature resistant composites are rapidly developing new research fields at the Institute. Health monitoring of building elements and materials is provided by acoustic emission research.
Functional Materials
Ferroelectrics and piezoelectrics are the original research area of the head of the institute, with special focus on damage in all its facets. Modifications of the microstructure, interaction with electrodes, micro- and macro-cracking, aging, and transport are all interrelated contributions to failure. Understanding and potentially circumventing these problems is a major concern in our research in view of technical applications in piezoelectric actuators and ferroelectric memories. Appropriate device concepts and material improvements are our product.
New key aspects in this field are:
- Multiferroic composites and their physico-mechanical characterization and the
- Development of lead-free piezoelectrics.
Multiferroic composites are currently studied for applications in highly sensitive magnetic sensors. Small magnetic fields, as for example those which arise in brain diagnostics, can also be detected in a room temperature environment. Present day sensors do not offer this possibility, because they must be cooled deeply.
We aim at developing materials with optimized properties and characterize their mechanical, magnetoelectrical, and remanent properties in order to establish a comprehensive data-set for modeling. One of the scientific essentials is to understand the coupling mechanisms from the microstructure up to the macroscale. The electrical and magnetic remanent properties can also be used as electrically writable and magnetically readable storage bits, which technologically means the downscale to nanostructures involved in the electronics industry.
Lead-free piezoelectrics are required to replace the toxic piezoelectric material systems currently used. Until now, no materials are known to reach comparable piezocoefficients to those present in the lead-containing ferroelectrics based on lead zirconate titanate (PZT) at the same low losses. Presently, PZT still dominates the world market. Due to the increasing alert to environmental issues and the related more restrictive legislation, the presently used materials must be replaced. The biggest problem are the considerable losses in the lead-free materials which generate heat-up and subsequent rapid degradation.
New material combinations are developed and different dopants are tested to improve electrical and electromechanical material performance. Material development and diagnostics are undertaken.
Independent of the other topics a new generation of organic heterojunction solar cell materials and structures is being developed at the Institute. Big molecules with large p-electron system are anticipated for their potentially high efficiency. Key points of this research area are structured electrodes which are based on bottom-up techniques on the nanoscale. Big surfaces and optimized optoelectronic properties are aimed at. Hybrids with inorganic systems are part of these activities.
Building Materials
High temperature materials and thermal insulation are rapidly developing new topics at the Institute. The aim is to match the material challenges involved in the new generation of high temperature solar plants concerning temperature stability and thermal insulation. Ceramics in a wider sense as well as composites play the main role in the investigation of these new materials.
Concrete is mainly investigated with respect to material properties and durability aspects. The work encompasses the influence of aging on the internal and external deterioration of high-performance concrete subjected to freeze-thaw cycles in combination with deicing salt (frost salt attack). In addition, work is underway for the detection of internal damage due to frost exposure using acoustic emissions as well as for the optimization of fiber reinforced self-compacting concrete regarding workability and durability.
Civil engineering material testing is an integral part of the services provided by the Institute.
For leaflets on the different topics please follow the links beneath (as of Dec 2009, in German):
- Classical ferroelectrics, lead-free piezoelectric materials
- High temperature ceramics and composites and
- Building materials testing and development
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