Nanostructure of ion-beam irradiated transition layers

 This project is embedded in the framework of the Sonderforschungsbereich (SFB) 422 at the TU Dresden. Transition layers are the intermixed zones of a multilayer where the respective pure elements are deposited with relativley high energies. Unlike "interfaces" their width is a few nm, so it is a rather 2.5 dimensional object. Two binary metallic systems are studied. The miscible, phase-building Fe/Al and the fully non-miscible Co/Cu.
Fig. 1 shows the principle of the investigations. The Multilayers are deposited by crossed-beam pulsed laser-deposited by the group of Prof. Pompe at the TU Dresden and investigated by means of Moessbauer spectroscopy, Rutherford Backscattering, various X-ray methods and transmission electron microscopy (at the HZDR as well as at the institute for applied physcis of the TU Dresden and the IFW Dresden). Afterwards the structure of the transition regions is modified by ion beam mixing and thermal annealing.
Fig. 2 shows the cross sectional TEM view of a Fe/Al multilayer. The deposited amounts of Fe and Al were sufficient for single layer thicknesses of dFe= 21 nm and dAl= 11 nm, if no intermixing would occur. The high kinetic energies of the particles (~100 eV) lead to the formation of a bcc solid solution of Al in Fe (not visible here, because it has the same structure than the pure Fe) and an amorphous layer with an average composition of Fe20Al80 between the pure elements during deposition. 
Fig. 3 shows the respective Moessbauerspectrum. Beside the alpha-Fe (cyan), one sees the signals of the bcc solid solution of Al in Fe (green) and the amorphous phase (orange). This little example shows that only a combination of different methods provide the full insight into the structure of the multilayer. For furhter results please see - Highlight-