SMALL-ANGLE NEUTRON-SCATTERING OF IONIC FERROFLUIDS

SANS measurements are performed for the first time on monophasic ionic ferrofluids. Intraparticle form factors and interparticle structure factors are both extracted from the scattering intensity in a zero magnetic field. The deduced radius of gyration of particles R(g) = 83 angstrom and their molar mass M(w) = 4.2 x 10(6) g/mol are in full agreement with magnetization measurements. The second virial of the osmotic pressure which is determined to be A2 = 4.7 x 10(-7) cm3 mol g-2 is positive, indicating that the experiment is performed in a 'good solvent' situation.