SMALL-ANGLE NEUTRON-SCATTERING EXPERIMENTS FROM COLLOIDAL DISPERSIONSAT REST AND UNDER SHEARED CONDITIONS

Neutron diffraction from charge stabilized shear ordered colloidal dis persions at rest and under sheared conditions are presented. A newly d esigned shear cell is used to generate a linear shear profile. Hexagon al scattering patterns were observed both at rest and under sheared co nditions. The stacking probability A is determined by measuring the in tensity dependence of the Bragg spots as a function of the angle betwe en the incoming neutron beam and the sample cell. The shear experiment s are discussed in terms of a continuous distortion [W. Loose and B. J . Ackerson, J. Chem. Phys, 101, 7211 (1994)] at small shear rates, and shear melting at higher shear rates. (C) 1998 American Institute of P hysics.