2O 4 Spinel-Structured Nanoparticles Using Hydrangea paniculata Flower Extract with Excellent Magnetic Property]]>

摘要

Nickel ferrite (NiFe~(2)O~(4)) spinel-structured nanoparticles (NPs) were synthesized by a green synthesis approach using Hydrangea paniculata flower extract. Green synthesis of NPs was preliminary monitored by a color change. Further confirmation was carried out using different techniques. X-ray diffraction analysis confirmed the cubic crystalline system (fcc) of NiFe~(2)O~(4). Energy-dispersive spectrum analysis showed the presence of iron, nickel, oxygen, and carbon. Scanning electron microscopy revealed the agglomerating nature of the NPs (30–50?nm). The specific surface area was found to be 46.73?m_(2)/g, revealing the average size D of NPs to be 24?nm. Transmission electron microscopy confirmed the spherical, oval, and irregular shapes of the NPs with a size range between 10?nm and 45?nm, and an average size of 28?nm. The magnetization of the obtained NiFe~(2)O~(4)NPs in a high magnetic field of 20?kOe was found to be 20?emu/g. The values of remanent magnetization ( M ~(r)) and coercive field ( H ~(c)) were found to be 1.1?emu/g and 28?Oe, respectively. In the process of magnetization reversal (with a small value of M ~(r)/ M ~(s), 0.055), NiFe~(2)O~(4)NPs had a loop with low energy loss, showing that the obtained NiFe~(2)O~(4)NPs were soft magnetic materials. The magnetization curve with a sigmoidal shape indicated that the obtained NiFe~(2)O~(4)NPs are super-paramagnetic material. In addition, the comparison of green synthesis with the methods available in the literature proved that the green synthesis is the best method. Thus, it is clear that green synthesis is a novel eco-friendly approach for the synthesis of magnetic NiFe~(2)O~(4)NPs.