Dynamic magnetic properties of monodisperse CoFe2O4 nanoparticles synthesized by a facile solvothermal technique

Monodisperse, unagglomerated nanoparticles of CoFe2O4 were synthesized by a solvothermal technique using various capping agents. Three sets of particles were synthesized having size similar to 7 nm, similar to 14 nm and similar to 23 nm. Detailed morphology study was done by X ray diffraction and High resolution Transmission Electron Microscope. Ac hysteresis loops of these samples were measured at room temperature within a frequency range of 50 Hz-600 Hz. We have reported the frequency dependence of coercivity and Specific absorption rate (SAR) and have found a very interesting result that the coercivity varies with different power of frequency for the particles of different size. Particles of sample A followed the Neel type of relaxation. The relaxation measurements were also done on all the samples to vindicate the occurrence of Neel type of relaxation. The SAR values and the fast relaxation proves that these particles can be utilized for hyperthermia treatment.