Electron Energy Loss Spectroscopy as a Tool to Probe the Electronic Structure in Intermetallic Alloys

Electron energy loss spectroscopy (EELS) is a technique which provides information on the electronic structure of materials and therefore can potentially be used to probe, in an electron microscope and at high spatial resolution (i.e. down to the nanometre level), the nature of the bonding in materials and extended defects. Such studies are particularly important in intermetallic alloys which are potential candidates for high temperature structural applications. In order to maximise the information retrieved from experiments and thus provide an understanding of the bonding mechanisms (i.e. whether there is experimental evidence for some covalent character in the bond) it is important to assess first whether the theory behind the calculations of the spectra from first principles, in particular the electronic structure calculations based on the local density approximation and the single particle approach, reproduces the experimental results in bulk alloys. Second, it is important to assess whether the experimental technique is sensitive to changes in electronic structure due to, for example, alloying with ternary elements.