Preparation of Co1-xNixFe2O4 nanoparticles by coprecipitation method

Co1-xNixFe2O4 nanoparticles were prepared by a coprecipitation method. The effects of precipitants and Co/Ni ratio on particle shape and magnetic properties of Co1-xNixFe2O4 nanoparticles were investigated. The physical properties such as particle size, phase, and magnetic properties of Co1-xNixFe2O4 nanoparticles depended largely on the Co/Ni ratio and precipitant as well as heat-treatment. In case of using NaOH as a precipitant, the synthesized nanoparticles were magnetite phase including a small part of impurity which is needle shaped and non-magnetic material. On the other hand, the nanoparticles synthesized by NH4OH precipitant were amorphous phase. The coercive force of the nanoparticles was increased drastically with increasing heat-treatment temperature in the range of 400-600 degreesC. The high coercive force of magnetic nanoparticles with the size of 20-30 nm was obtained up to 1450-1800 Oe.