Chemical bonding and electronic structure in MAX-phases

What is it about?

The MAX-phases combines the best combinations of ceramics and metals. Bulk construction materials are made by a powder metallurgical process at high pressure and temperature (sintering). Parts of combustion engines, rockets and heating elements Thin films and surface coatings are made by building up individual atomic layers (sputtering). Cutting tools, electrical switches, and diffusion barriers It is important that single crystal material (thin film) is employed in order to understand and obtain the basic physical properties The target of the research is to understand and systematize how the underlying electronic structure and chemical bonding affects the macroscopic properties

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Why is it important?

Generally, there are three different types of bonding; relatively weak M 3d – A 3p bonding close to the Fermi level, as well as M 3d - C 2p and M 3d – C 2s bonds, that are stronger and deeper in energy than the Fermi level. The electronic structure and chemical bonding are significantly different in the nitrides than in the isostructural carbides. A modification of the chemical bond strengths can also be achieved by exchanging the A-element which results in a change of the valence electron population (e.g., Al to Si, and Ge in MAX-phases) or changing the crystal structure (211 to 312, 413). This means that the chemical bond length/strength and materials properties can be tailored for specific applications.

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