The preparation of MnZn-ferrite nanoparticles in water–CTAB–hexanol microemulsions

Magnetic MnZn-ferrite nanoparticles with a narrow size distribution were prepared in water–CTAB–hexanol microemulsions. The region of microemulsion stability in the system was determined, using the titration method, as a function of the temperature and of the type and concentration of solutes in the aqueous phase. The nanoparticles were prepared in a two-step process: the precipitation of the corresponding hydroxides, followed by oxidation of the Fe2+. The particle size was controlled by the composition of the microemulsion and the concentration of the reactants (the corresponding sulfates and a precipitation agent, tetramethyl ammonium hydroxide) in the aqueous solution of the microemulsion. The specific magnetization of the nanoparticles (measured at 13 kOe) was found to depend mainly on particle size: ranging from 1.3 emu g−1 for particles of approximately 2 nm in size to 7.3 emu g−1 for particles of approximately 5 nm in size.