The effect of shear on a lyotropic lamellar phase is studied by the means of small-angle light scattering and direct microscopic observations. We found a complex behavior that can be described by a shear diagram. This diagram exhibits successively as a function of shear four different steady states. After a transition to a phase of monodisperse multilamellar vesicles with no long-range order there is a transition to the same vesicles exhibiting long-range order. At even higher shear rates, there is a transition between this ordered population of vesicles of size typically $1\mu \mathrm{m}$ to another ordered state made of vesicles which are much bigger (from 10 to $50\mu \mathrm{m}$).

• Received 2 July 1996

DOI:https://doi.org/10.1103/PhysRevLett.78.1496