Magnetic Properties of γ-Fe_2O_3/Ni_2O_3 Composite Magnetic Nanoparticles and Ferrofluids

γ-Fe2O3/Ni2O3 biphasic composite magnetic nanoparticles were prepared by chemical co-precipitation technology and their stable magnetic fluids were synthesized by the method of Massart.The magnetization curves of the magnetic particles and of the ferrofluids of different volume fractions were measured by VSM.The results indicated that the saturation magnetization of γ-Fe2O3/Ni2O3 ferrofluids was related to the volume fraction of the particles in the ferrofluids(v),the non-magnetic layer on the particle surface and the magnetic properties of the carrier liquid,and that the saturation magnetization measurements of the ferrofluids of different volume fractions were in good agreement with the theoretical value.The above results suggested that γ-Fe2O3/Ni2O3 composite magnetic particles are more suitable for synthesizing ferrofluids than other single-phase magnetic particles.