Structural Transitions in Sodium Chloride Nanocrystals

High resolution ion mobility measurements have been used to examine structural transitions in $(\mathrm{NaCl}{)}_n{\mathrm{Cl}}^{-}$ nanocrystals with between 30 and 40 NaCl units. Transformations between bulk fragment geometries with different $j\times k\times l$ dimensions are observed at ambient temperatures. In some of these transformations, close to half the atoms are relocated, yet the Arrhenius activation energies are less than 0.6 eV. A surface diffusion mechanism is proposed to explain the remarkably low activation energies.