We have performed synchrotron small-angle x-ray diffraction experiments on charge-stabilized colloidal crystals. The mean squared displacements, obtained from Debye-Waller factors, decrease with increasing density beyond freezing. Irrespective of the range of the repulsion, our data and previous results lie on a common curve, linearly scaled between the melting and close-packed densities. Surprisingly, the excursions are smaller than predicted by theory.

• Received 12 July 2000

DOI:https://doi.org/10.1103/PhysRevLett.86.4855