Core-shell and magnetic structure of barium hexaferrite fluids studied by SANS

We report on small angle neutron scattering measurements with polarised neutrons on ferrofluids (FF) based on barium hexaferrite. The combination of magnetic and isotopic H/D contrast variation of the carrier liquid, dodecane, allows to identify and separate between magnetic and non-magnetic components. In the FF a core-shell structure was found where the shell of surfactants was found to be impenetrable for the carrier liquid. Additionally, magnetic aggregates and isolated surfactant molecules were detected. As results the sizes of the structural parts were given.