ast sintering techniques, such as Spark Plasma Sintering (SPS) or Field Assisted Sintering (FAST) have recently demonstrated to be particularly effective producing bulk materials presenting a nanometric grain size. But besides controlling the grain growth these new sintering techniques allow obtaining other unusual characteristics that are still poorly investigated. The possibility to realize a localized doping at the nanometric scale, through grain surface decoration, represents one of them.
In this approach a small amount of a dopant or a second phase (or of their precursors) is deposited on the external surface of the nanoparticles using a very simple solution technique. The nanopowders are then sintered by SPS or HP-FAST. Since ctaionic diffusion is a very slow process in comparison with the SPS processing, interaction between the involved phases can be controlled with a sub-nanometric accuracy.
This approach and the related mechanisms are still poorly investigated, but they show a great potential as alternative to the much more complex core-shell and ALD techniques, for the synthesis of bulk nanocomposites with carefully controlled microstructures.
Related publications:
I.G.Tredici, G. Spinolo, U.Anselmi-Tamburini, “Localized doping and apparent fast interdiffusion produced in bulk nanocrystalline ceria and zirconia by FAST/SPS”, in preparation