Influence of the suspension stability on the deposition of cobalt ferrite particles under an applied magnetic field

Cobalt ferrite nanoparticles were synthesized with coprecipitation or with the hydrothermal method. Stable water suspensions were prepared from the as-synthesized nanoparticles, with the addition of citric acid as a surfactant, and then used for the preparation of deposits under an applied magnetic field. The morphology of the cobalt ferrite nanoparticles was investigated with a transmission electron microscope, and their magnetic properties were measured with a vibrating-sample magnetometer. The particle sizes and their magnetic properties influenced the stability of the suspensions, which were evaluated in terms of their zeta-potentials and the sedimentation time. Furthermore, the same parameters significantly influenced the morphology of the deposits, which were observed with a scanning electron microscope.