Size dependent heating ability of CoFe_2O_4 nanoparticles in AC magnetic field for magnetic nanofluid hyperthermia

摘要

We investigated the size dependent magnetic properties and heating mechanism of spinel CoFe_2O_4 nanoparticles, which synthesized using the nonhydrolytic thermal decomposition method. The size of CoFe_2O_4 nanoparticles was arranged with the variation of solvent type, reflux time, and reflux temperature. The optimum size range was determined for magnetic fluid hyperthermia. The particles with 9.9 ± 0.3 nm average diameter have the highest heating ability in the AC magnetic field having 3.2 kA/m amplitude and 571 kHz frequency. The maximum specific absorption rate of 22 W/g was obtained for 9.9 ± 0.3 nm sized CoFe_2O_4 nanoparticles. The calculations and experimental results showed the dominancy of Brownian relaxation at the heat production of synthesized 9.9 ± 0.3 nm nanoparticles. In contrary, the magneto-heating in 5.4 ± 0.2 nm particles mainly originated from Neel relaxation.