Micorstructural and magnetic characterisation of a new kind of magnetic hybrid materials

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Classical magnetic hybrid materials contain either magnetically soft or magnetically hard particles. Thus, they show either an active magnetorheological effect or exhibit passive magnetorheological properties after magnetization of the magnetically hard particles. Within this research association of German and Russian project groups we combine magnetically hard and soft particles in an elastomeric matrix to provide a combination of active and passive magnetorheological properties. In this context, it is the central goal of the research association to synthesize tailored magnetic hybrid materials for sensor applications based on a detailed microscopic understanding of the material properties. Within the subproject described here, microstructural investigations as well as the experimental analysis of the magnetic interparticle interactions are in focus of the working program. The microstructural investigations use X-ray microtomography measurements allowing a three-dimensional evaluation of the particle distribution with single particle resolution. In the project phase applied for we will especially focus on the evaluation of reorganization of small particles in the hybrid material since these play an important role in the theoretical description of the material. Moreover structural changes as well during magnetization processes as under mechanical load will be examined by microtomography. The respective data serves as well as an input as as a benchmark for the simulations undertaken by the theoretically working groups within the research association. The investigations of magnetic interparticle interaction between the different particles using First Order Reversal Curves (FORCs) will be extended to clarify the influence of the particle shape on the interaction with the matrix and thus on structural reorganization and magnetic behaviour of the hybrid materials. The detailed interpretation of the data requires a deeper theoretical understanding of the curves, which will be provided by the theoretically working groups. In total, we expect that the project will provide detailed information about the relation between microstructural changes and macroscopic properties of the magnetic hybrid materials. This information will provide the basis for a prediction of certain material properties, which can be achieved by respective changes in composition of the material.