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-