Metallic nanocrystalls are interesting subject for investigations due to their application in catalysis, cold emitters, self-assembled systems etc. Nanocrystalls are difficult for studies with classical crystallographic methods. Transmission electron microscopy and diffraction are widely used to study structure of such objects.
Metallic nanocrystalls of size of few or few tens of nanometers give characteristic electron diffraction patterns. In the case of Ni and Pt nanoparticles 10-20 nm in size electron diffraction pattern rings characteristic for fcc structure as well as additional weak and sharp rings, which can be indexed as forbidden reflections are observed. These rings can originate from outer shell formed around metallic core. Computer simulations of electron diffraction patterns for different structural model of the core and oxide or carbide envelope are presented. Comparison of experimental and calculated results will be performed. Discussion of detail differences for various structural models concerning core and shell construction will be also done.