Mechanical properties of face-centered cubic supercrystals of nanocrystals

Nano Lett. 2010 Jul 14;10(7):2363-7. doi: 10.1021/nl1001313.


We report the first nanoindentation studies of well-ordered nanocrystal supercrystals composed of 7 nm lead sulfide nanocrystals stabilized with oleic acid ligands as a model system. Their modulus and hardness were found to be similar to hard polymers at 1.7 GPa and 70 MPa, respectively, and the fracture toughness was 40 KPa/m(1/2), revealing the brittle nature of these materials. The mechanical properties are dominated by the organic capping agents surrounding the inorganic cores. The close-packed structure distributes stress evenly increasing the modulus and hardness. The relatively short ligands are not likely to be highly interdigitated leading to low dissipation during crack propagation and a low-fracture toughness value.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.