Heating Power of Coated Fecov Magnetic Nanoparticles

The effect of coatings on the heating curves of magnetic nanoparticles was studied in this Thesis. Iron cobalt vanadium (FeCoV) nanoparticles with oxide (CoOFe2O3) and graphite (C) coating to prevent oxidation, were synthesized through thermal plasma processing method. The magnetic nanoparticles had an average diameter of 30 nm. In the case of FeCoV with oxide coating, the initial diameter of the pure FeCoV nanoparticles on average was 30 nm but after oxidation 5 nm thick oxide layer was created. As a result of this oxidation, the magnetic core of FeCoV nanoparticles was shrunk from 30 nm to 20 nm in diameter. Graphite coating with a thickness of 10 nm was added uniformly to 30 nm in diameter of FeCoV nanoparticles. These magnetic nanoparticles were exposed to an ac applied magnetic field and their heating responses were measured. The measurements were done at frequency of 175 kHz and intensity of the magnetic field with different current values of 5 A, 10 A, and 15 A. The heating performance of magnetic nanoparticles described by Specific Absorption Rate (SAR) was calculated by finding the initial slope of the heating curve with respect to time. It was found that the maximum value of SAR was obtained when applied frequency and current were at 175 kHz and 15 A, respectively. Results were analyzed to find the coating effect on the heating rate. The most significant conclusion based on our research is to see that FeCoV magnetic nanoparticles with graphite coating had higher heating power than FeCoV with oxide coating.