I have a HR-TEM image of pure Aluminum which wass ball milled for prolonged hours. HR TEM images indicate that there are significant amount of amorphous region coexisted with crystalline Aluminum. However, XRD of the powders showed fully crystalline Al fcc peaks and didn't show any amorphous hump. Can anyone tell me why amorphous Al observed in TEM whereas it's not in XRD. HRTEM Image is attached.
PS: TEM sample prepared by FIB and well cleaned before HRTEM.
Hi Prathap,
you should see a very broad continuous (gas-like) background from amorphous Al in XRD because there is no any set of discrete distances between Al atoms.
If an HRTEM image does not show lattice fringes, then this does NOT provide evidence of an amoprhous state - you could also have tiny crystallites most of which are just nor orientatied in the Bragg condition for the specific viewing direction. Do propoer electron diffractioln to check. If the area in the top of your images is indeed partly amorphous, then you will have to work out what volume fraction is amorphous. If it is only a tiny fraction, then XRD will not find it.
The amorphous hump you are expecting can be very broad so it "blends" in with the background. You do not have nano paritcles that would lead to broad reflections but a purely amorphous material (top of you HRTEM). As mentioned above electron diffraction of the amorphous ares will help with that problem.
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