Application of Mn x Fe1–x Fe2O4 (x = 0–1) Nanoparticles in Magnetic Fluid Hyperthermia: Correlation with Cation Distribution and Magnetostructural Properties

Optimization of manganese-substituted iron oxide nanoferrites having the composition Mn x Fe1–x Fe2O4 (x = 0–1) has been achieved by the chemical co-precipitation method. The crystallite size and phase purity were analyzed from X-ray diffraction. With increases in Mn2+ concentration, the crystallite size varies from 5.78 to 9.94 nm. Transmission electron microscopy (TEM) analysis depicted particle sizes ranging from 10 ± 0.2 to 13 ± 0.2 nm with increasing Mn2+ substitution. The magnetization (M s) value varies significantly with increasing Mn2+ substitution. The variation in the magnetic properties may be attributed to the substitution of Fe2+ ions by Mn2+ ions inducing a change in the superexchange interaction between the A and B sublattices. The self-heating characteristics of Mn x Fe1–x Fe2O4 (x = 0–1) nanoparticles (NPs) in an AC magnetic field are evaluated by specific absorption rate (SAR) and intrinsic loss power, both of which are presented with varying NP composition, NP concentration, and field amplitudes. Mn0.75Fe0.25Fe2O4 exhibited superior induction heating properties in terms of a SAR of 153.76 W/g. This superior value of SAR with an optimized Mn2+ content is presented in correlation with the cation distribution of Mn2+ in the A or B position in the Fe3O4 structure and enhancement in magnetic saturation. These optimized Mn0.75Fe0.25Fe2O4 NPs can be used as a promising candidate for hyperthermia applications.