The research on materials in bulk form encompasses in principle all materials that are not dependent on certain microstructures (thin films, nano-materials etc.). Its focus lies on how material properties are governed and influenced by chemical composition and crystal structure. For example, one study considers how changes of composition relate to the magnetic properties of alloys based on Fe2P, while the crystal structure is retained. Another angle of the same general focus is found in studies of low-dimensional structures built up by layers (~2 D) or by chains (~1 D).
The solid substances are often synthesized using experimental techniques where the elements react with one another at high temperatures. Depending on the properties of the reacting elements different synthesis methods are called for, e.g. arc melting or induction heating. The materials may be used within construction, for hydrogen storage or as magnetic materials. In some cases, a special after-treatment (e.g. oxidation) at ambient temperature may accomplish a radical structural change of the solid under depletion of one of its elements through contact with a liquid that does not dissolve the solid. That element is leached out into the liquid while the solid is not broken apart. The method offers a unique route to new materials.
The research on magnetic materials focuses e.g. on the magnetocaloric effect, which means that the material temperature changes when it is brought in or out of a magnetic field. These materials can be used e.g. in new magnetic refrigerators with a higher energy efficiency than conventional refrigerators.
Another study is concerned with the fundamental aspects of magnetic coupling in low dimensional systems, exemplified by carefully selected crystal structures and element combinations. The variation of composition may create ferro-, ferri- and antiferromagnetism as well as incommensurate helimagnetism, with possibilities of chemical tuning of the magnetic properties. In some cases also multiferroic materials occur, i.e. materials sensitive to both an electric and magnetic field.
Certain types of materials have the possibility to absorb and store large amounts of hydrogen. These materials have applications in energy storage in batteries or hydrogen tanks for fuel cell-powered engines. The research focuses on finding new lightweight materials with good hydrogen storage properties.
Low dimensionality and soft chemistry
Properties of materials depend strongly on the dimensionality, e.g. magnetism, conductivity and ferroelectricity. How the physical properties relate to structure and composition of low-dimensional materials is not yet fully understood and they need studying. In the future, these properties might be tuned and turned into various technical applications. Soft chemistry (“chimie douce”) that works particularly well with low-dimensional structures makes it possible to create metastable phases, i.e. solids that cannot endure the high temperatures of conventional synthesis methods.