Concentration and temperature effect in microstructure of ferrofluids

The spatial correlations in magnetite-based ferrofluids (FF) with pentanol carrier have been investigated by small-angle neutron scattering, as dependent on the concentration of magnetic phase (C=0.6-20vol%) and temperature (20-85oC). Some peculiarities in the structure of FF were detected. An anomalous increase of short range order by heating of low-concentrated FF (C∼0.6-4.0vol%); the formation of short range order at ambient temperature which weakens at growing concentrations C=7-14vol% and the existence of a stable structure at the highest concentration C∼20vol% when particles' shell interpenetrate. Neutron scattering data are discussed with regard to the particles' intrinsic magnetisation enhancement induced by ordering