Effect of the volume fraction of solids on the concentration polarization around spheroidal hematite particles

Abstract

We present the first experimental results on the effect of the particles content (up to ϕ = 20% volume fraction of solids) in the low frequency dielectric dispersion (LFDD) of suspensions of hematite (α-Fe₂O₃) prolate spheroidal colloids. Two α-relaxations, each one associated to a characteristic dimension of the particles, are clearly observed, but they present different dependencies with volume fraction. Accounting for particle–particle interactions, in terms of models for spheres, allows a comprehensive interpretation of the mechanisms involved, suggesting the presence of a nematic phase in our suspensions.