Suppression of an ordered fluid phase by admixture of small particles

Abstract

Suspensions of fine particles of cobalt in a surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT), were prepared by metal-atom synthesis. The particles were rods about 110 Å long by 30–40 Å wide. AOT in pure form shows a hexagonal columnar phase. The addition of only 2 vol % of Co particles suppresses this phase, as shown by optical microscopy and x-ray scattering. At lower Co contents, where the hexagonal phase still exists, segregation of Co particles to isotropic regions could be observed as the temperature was raised to the (H+I) two-phase region.