pic taken from brown uni.
a)two-dimensional hexagonal pyrolitic graphite,(dots only) b) polycrystalline aluminum(rings only) c) polycrystalline hexagonal p-graphite(rings and dots)
Electron diffraction pattern looks rather different depending on the structure. The rings are due to a random orientation as in powder form but within each speck there is still regular arrangement. A ring consist of many dots joined together till it looks like a continuous . See link if you want to know more. I am learning more!
