Synthesis and characterization of superparamagnetic fe₃o₄ nanoparticles for ferrofluid application

Nanocrystalline Fe₃O₄ particles of controlled size were synthesized by a chemical coprecipitation method. X-ray diffraction patterns confirm the synthesis of single crystalline phase of Fe₃O₄ nanoparticles with the lattice parameter 8.4090 A°. The particle size is 11.5 nm and increases to 20 nm after annealing. TEM image shows that the sample contains well dispersed nanoparticles with an average particle size of the order of 20 nm. Magnetic measurements show the superparamagnetic nature of the sample that is also confirmed by EPR measurements. The saturation magnetization is 42 emu/g. The results are explained adequately.