STACKING OF HEXAGONAL LAYERS OF COLLOIDAL PARTICLES - STUDY BY SMALL-ANGLE NEUTRON-DIFFRACTION

Quantitative interpretations of scattering patterns from a charge-stab ilized colloidal dispersion are described. The scattering patterns for a range of structural models based upon the stacking of layers of hex agonally arranged particles are calculated and compared with experimen tal data. Inclusion of both position and intensities is essential in t his analysis to distinguish between the alternative structures. The st ructure appears to be most closely represented as layers of particles stacked in an hexagonally close packed sequence. This contrasts with t he usual observations of cubic structures.