Hydrothermal synthesis of mixed cobalt-nickel ferrite nanoparticles

The hydrothermal synthesis of CoxNi1−xFe2O4 nanoparticles (NPs) from mixed FeCl3 / CoCl2 / NiCl2 precursor solution has been investigated as a function of reaction temperature, using the complementary characterisation techniques of X-ray diffractometry, transmission electron microscopy, energy dispersive X-ray analysis and electron energy loss spectroscopy. At pH ∼ 8, the HS of Co0.5Ni0.5Fe2O4 NPs, up to ∼ 25 nm in size, was found to proceed through the formation and dissolution of intermediate Fe(OH)3 and [FeCoNi2(OH)8]+.[Cl−.H2O]− phases.