To Core-Shell allows to model a core-shell spherical particle. As an example a Si core will be embeded in a Ge. First the Si crystal struture is loaded and the ToCoreShell menu item of menu Miscellany is selected.
To Core-Shell allows to model a core-shell spherical particle. As an example a Si core will be embeded in a Ge. First the Si crystal struture is loaded and the ToCoreShell menu item of menu Miscellany is selected.
By default a core of diameter 0.192 nm is defined. Use the Duplicate sliders to make it larger. A 12 × 12 × 12 precipitate is displayed in Fig. 2. & Figure 3:
Select the Shell pane, load the Ge structure and duplicate it 20 × 20 × 20 (Fig.4).
The orientation relationship between the Si core and the Ge shell is defined using the Core pane Direction (Figures 8a, 8b).Note that the directions are specidied with respect to the cell sides.
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Figure 8a Si-Ge [uvw]=[111] core direction along Oz ZoneAxisGeometry. |
Figure 8b Si-Ge [uvw] rotation of [uvw]=[111] axis, i.e. of Oz . |
The whole model is loaded (Fig. 11) and simple SAED, projected potential, HAADF and WPOA images calculated (Figures 12a, 12b, 12c, 12d). Indeed to perform accurate dynamical calculations it is necessary to introduce the slices into the Multislicer procedure.
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Figure 12a Si-Ge model SAED. |
Figure 12b Si-Ge model projected potential. |
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Figure 12c Si-Ge model HAADF image. |
Figure 12d Si-Ge slice WPOA image. |
Since the model is pretty thick it is necessary to slice it in ~0.2 nm thick slices. The model can be sliced directly with the To CoreShell window or saved and sliced with the To Slices window.
A sequence of 40 slices is saved on disk (anyName_0000, anyName_0001,..., anyName_0039).
To perform multislice calculations, load the first (top) slice (Fig. 13), start the Multislicer and load all the slices (Fig. 14).
The wave-function at the exit plane of the core-shell model is opened with the HRTEM Imager and further simulations including aberration, change of defocus or missalignments performed (Fig. a).