Factors Affecting the Heating Efficiency of Mn-doped Fe3O4 Nanoparticles

Abstract MnxFe3-xO4 (x = 0, 0.1, 0.3 and 0.5) samples were synthesized using the co-precipitation method and its structural and magnetic properties were correlated to the heating characteristics in an ac magnetic field. The effective magnetic anisotropy constant of the samples measured using electron spin resonance (ESR) was between 15.3 and 16.5 kJ/m3. The effective magnetic anisotropy increased to 31.3 kJ/m3 on doping Fe3O4 with Co. The hyperthermia response of the samples was tested using infrared thermography and the effective specific absorption rate (ESAR) was obtained in the range of 15-21 × 10-9 W/gOe2Hz. The ESAR decreased when the effective magnetic anisotropy was 16.5 kJ/m3, as well as when it increased to 31.3 kJ/m3. The effect of magnetic anisotropy and polydispersity on the hyperthermic efficiency was intensively analyzed employing theoretical models.