The magnetic characterization and determination of the grains size distributions of magnetic particles used for magnetic fluids (MF) preparation were performed. The characterization was done by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC) and by magnetic measurements. The investigated MF exhibits higher blocking temperature Tb but lower magnetization value then the pure powder of nanoparticles used for MF preparation without surfactant coating. The mean diameter of Fe3O4 nanoparticles was calculated from Tb (Dm=11.5 nm) and from XRD (Dm=10.1 nm) and compared with particles after their stabilization with lauric acid (D m=12.2 nm). Morphology and grains size distribution were examined by FESEM (mean diameter of the grains D0=16.0 nm). DSC curves show three endothermic peaks at 51°C, 130°C and 222°C: the first one corresponds to melting temperature and the third one to the boiling temperature of the lauric acid. Peak at temperature 130°C is a proof of the existence of surfactant double layers.
- Magnetic fluids
- Small magnetic particles
- Thermal stability of structure
ASJC Scopus subject areas
- Physics and Astronomy(all)