  Nanocrystals, used as building blocks, may self-assemble in long-range
ordered assemblies socalled supracrystals. Different structures FCC, BCC but
also Frank-Kasper phases have been observed and the roles of the soft ligands
surrounding the rigid crystalline cores in the self-assembly process is not yet
well understood and need further study. The mechanical behavior under
hydrostatic pressure of 3D single FCC crystals built by gold nanoparticles has
been investigated using HP-SAXS and compared with pure alkane, corresponding to
the ligand chain. No structural transition has been observed up to 12 GPa, but
a large increase of the supracrystals bulk modulus has been measured.
