New materials are needed to enable future technological developments in areas such as sustainable energy technologies and energy-efficient processes. One trend in new materials is that their chemical complexity is increasing, i.e. the materials are multinary and often consist of more than 10 elements, e.g.superalloys and so-called high-entropy alloys. However, the number of possible element combinations in multicomponent systems is almost unlimited. Therefore, efficient research strategies and the simultaneous production of complete material systems or at least large composition ranges of multi-component systems are required. This is made possible by combinatorial materials research through the production of material libraries and their high-throughput characterization
Combinatorial materials research develops and uses advanced methods for the efficient discovery and further development of new materials. So-called material libraries are produced by combinatorial coating methods. These are produced in an experiment under identical conditions and contain several hundreds to thousands of materials per material library. The material libraries are automatically analyzed using suitable high-throughput characterization methods. This results in multidimensional data sets that are visualized in the form of composition-processing-structure property maps.
Material libraries can be produced by combinatorial magnetron sputtering processes. Sputtering is a versatile process that is also widely used in industry. Therefore, knowledge from screening material libraries can be applied to industrial applications. The main methods for producing material libraries with well-defined composition gradients are co-deposition and multilayer deposition of wedge-shaped layers. In co-deposition, at least two sputtering sources are used simultaneously, both targeting the substrate to be coated. In one of our co-deposition systems up to five sources can be operated simultaneously. The co-deposition process results in atomic mixing of the deposited layer. This method is particularly suitable for the production of metastable materials. However, the production of complete material systems covering a composition range from 0 to 100 at.% is not possible with co-deposition. Complete ternary systems are prepared as follows: nanoscale wedge-shaped layers are deposited, oriented at 120° to each other. Phase formation is achieved by annealing at suitable temperatures after deposition. The thickness of the layer libraries is in the range of several hundred nanometers to allow high-throughput characterization methods and to avoid nanoscale effects (if these are not the subject of the research).
Selected publications and animations on the topic:
Synthesis of material libraries: wedge-type multilayers
Synthesis of material libraries: Co-Deposition
Automated high-throughput characterization of material libraries produces large multidimensional data sets that can now only be handled and analyzed by computer programs. We are concerned with applying machine learning methods to experimental materials science, especially in combinatorial materials research. As a basis for this, the Chair has built a specific research data management system in which all data from high-throughput experiments enter. Software tools have been and continue to be developed for automated data analysis, and for visualization of highly multidimensional data. Development and use of AI assistants (specialized software that uses artificial intelligence to solve specific tasks) is an ongoing topic.
The Chair uses methods of microsystems engineering and nanotechnology to develop new materials. Manufacturing methods of microsystems technology such as photolithography, coating and etching processes are used to produce microsystems for materials research.
Selected publications on the topic:
Nanostructures and nanomaterials