Method of polyvinyl alcohol substitution in aqueous magnetic colloids

Publisher Website
Google Scholar
Abstract
A method of freezing the spatial distribution of magnetic grains in a water-base ferrofluid is described. The procedure is based on the progressive substitution of the water by a polyvinyl alcohol. The resulting samples are solid and can be studied by electron micrography. With a system of Fe 3O4 grains with a diameter of 100 A and a 3 % volume fraction of magnetite, we find spheroidal aggregates of average size 0.5 μ at zero magnetic field. At a field of ∼ 100 G, the aggregates appear as long chains