Periodic structures in colloidal crystals with oscillatory flow

Periodic structures in a colloidal crystal submitted to an oscillatory flow

2014 A colloidal crystal retained in a cylindrical tube and submitted to an oscillatory flow exhibits under certain conditions a spatially periodic pattern. Optical observations of the colored flecks show the existence of a continuous modulation of the orientation of the crystallites at the tube surface. It is due to the presence of a transverse component in the velocity field. We also present ...

Slip, yield, and bands in colloidal crystals under oscillatory shear.

We study dense colloidal crystals under oscillatory shear using a confocal microscope. At large strains the crystals yield and the suspensions form shear bands. The pure harmonic response exhibited by the suspension rules out the applicability of nonlinear rheology models typically used to describe shear banding in other types of complex fluids. Instead, we show that a model based on the coexis...

Unstable Periodic Structures in Nematic Liquid Crystals

Periodic average structures of colloidal quasicrystals.

We experimentally study the phase behaviour of a charge-stabilized two-dimensional colloidal monolayer which is subjected to a one-dimensional quasiperiodic substrate potential. Upon increasing the laser intensity, we observe a transition from a periodic to a quasiperiodic state. It proceeds via the formation of an intermediate periodic average structure (PAS) which is related to the quasiperio...

Tailoring of phononic band structures in colloidal crystals.

We report an experimental study of the elastic properties of a two-dimensional (2D) colloidal crystal subjected to light-induced substrate potentials. In agreement with recent theoretical predictions [H. H. von Grünberg and J. Baumgartl, Phys. Rev. E 75, 051406 (2007).10.1103/PhysRevE.75.051406] the phonon band structure of such systems can be tuned depending on the symmetry and depth of the su...