We report on the elastic modulus of 3D superlatticesof single domain ε -Co nanocrystals self-assembled in face-centered cubic structures, so-called supracrystals. The effects of nanocrystal size, probe size, and supracrystal morphology on the elasticproperties of supracrystals are investigated by nanoindentation measurements using an atomic force microscope. We show that elastic moduli of supracrystals of single domain ε -Co nanocrystals are invariant on varying the nanocrystal size and supracrystal morphology (fi lms or faceted shape) produced through heterogeneous (solvent evaporation) growth process. A mechanical model is proposed to analyze elastic properties of supracrystals that differ from classical composite materials. These results are explained interms of nanocrystallinity, that is, the crystalline structure of nanocrystals, which is a key parameter in achieving supracrystals of diff erent nanocrystal sizes with robust elastic properties.
Source : Morphology, nanocrystallinity and elastic properties of single domain ε-Co supracrystals. M.Gauvin, N. Yang, E.Barthel, I.Arfaoui, J.Yang, P.A. Albouy and M.P.Pileni, J.Phys. Chem. C, 2015,119, 7483−7490.