Comparison of the influence of superparamagnetic nanoparticles concentration and coverage on the alternating magnetic field thermal effect

Magnetic nanoparticles (MNP)s of Fe3O4 were synthesized in the co-precipitation reaction of iron chlorides dissolved in water and ammonia water. To produce polyethylene glycol (PEG) coatings of the NMPs, we added PEG to the ammonia water during the fabrication process. Magnetic fluids, ferrofluids, for research were prepared as oleic acid suspension of bare and PEG-coated nanoparticles at four concentrations. The results of the conducted calorimetric experiments confirmed that the efficiency of heating ferrofluids strongly depends on the concentration of nanoparticles in fluids. The results also indicate that the ferrofluids containing PEG-coated NPs heat up more than ferrofluids with bare nanoparticles. They are characterized by a higher specific absorption rate (SAR) value calculated from the initial slope of temperature versus time curve during heating. •The production and properties of bare and PEG-coated Fe3O4 nanoparticles, NPs, are described.•PEG-coating of Fe3O4 enhanced the magnetic heating efficiency.•The nature of SAR dependencies on NPs concentrations and magnetic field strength are discussed.