Abstract:

Four spinel ferrite magnetic nanoparticles (SFMNPs): cobalt ferrite (CoFe2O4), nickel ferrite (NiFe2O4), copper ferrite (CuFe2O4) and zinc ferrite (ZnFe2O4) were synthesized by the modified sol-gel technique and then annealed at 1000 °C for 5 h. Their crystallographic, morphological, microstructural, and magnetic properties have been studied. X-ray diffraction (XRD) confirmed the spinel cubic structure with the 𝐹𝑑3̅𝑚space group of all the NPs and the single crystalline phase of two as-prepared NPs: NiFe2O4 and CuFe2O4. However, both, CoFe2O4 and ZnFe2O4, as-prepared NPs revealed the presence of additional peaks of CoO and ZnO with α- Fe2O3 respectively. Moreover, the crystallite size (CS) varied between 16 and 40 nm. Rietveld analysis showed single crystalline phase and an increase in CS for all the annealed samples, where CS ranged between 25 and 73 nm. Characteristic magnetic parameters were determined by vibrating sample magnetometer (VSM). Room temperature ferrimagnetic behavior was confirmed by VSM measurements. The saturation magnetization (Ms) was found to decrease in the order NiFe2O4 > CoFe2O4 > CuFe2O4≫ ZnFe2O4 under the same synthetic method and annealing temperature. The specific absorption rate (SAR) which is released on the exposure of the ensemble of synthesized particles to an alternating electromagnetic field is calculated using experimental measurements. The highest SAR value was for the annealed CuFe2O4 (65.6 W/g) with the least CS (26 nm). It is believed that hysteresis loss is behind the dissipation of heat by the studied SFMNPs. Thus the annealed CuFe2O4 can be considered as potential candidates for biomedical applications among the others.