Evidence of particle-particle interaction quenching in nanocomposite based on oleic acid-coated Fe3O4 nanoparticles after over-coating with essential oil extracted from Croton cajucara Benth

• Published in: Journal of magnetism and magnetic materials 2018-11, Vol.466, p.359-367
• Main Authors: Medrano, J.J.A., Aragón, F.F.H., Leon-Felix, L., Coaquira, J.A.H., Rodríguez, A.F.R., Faria, F.S.E.D.V., Sousa, M.H., Ochoa, J.C. Mantilla, Morais, P.C.
• Format: Article
• Language: English
• Subjects: Magnetic measurements; Magnetite; Nanoparticles; Particle interaction; Surface coating
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2018.07.036

•Low polydispersity of the particle size in magnetite nanoparticles.•Monolayer and bilayer-coated magnetite nanoparticles.•Cluster-glass and superparamagnetic behavior were found within the monolayer nanostructure.•Magnetic nanoparticles with promising phytotherapeutic applications. This study reports on the synthesis and characterization of oleic acid (OA)-coated Fe3O4 nanoparticles (Fe3O4@OA) and AO plus essential oil (EO)-coated Fe3O4 nanoparticles (Fe3O4@OA/EO). The EO was extracted from Croton cajucara Benth (CCB) leaves; a plant from the Brazilian Amazon region. Structural and morphological characterizations were carried out using X-ray diffraction (XRD) and transmission electron microscopy (TEM) images, respectively. Additionally, thermogravimetric analysis and magnetization measurements (hysteresis cycle, zero field-cooled-ZFC, field-cooled-FC, and AC susceptibility) were used to assess thermal and magnetic properties of the as-fabricated samples. Rietveld refinement of XRD pattern confirmed the formation of magnetite phase with no extra phases, whereas TEM images revealed spherically-shaped nanoparticles in the Fe3O4@OA and (Fe3O4@OA/EO) samples with a mean physical size of 8.5 nm and 10.1 nm, respectively. ZFC and FC curves revealed the occurrence of blocked/frozen state below the maximum peak (Tmax) at ∼81 K and ∼40 K for the Fe3O4@OA and (Fe3O4@OA/EO) samples, respectively. Moreover, low-temperature AC susceptibility vs. T curves recorded in the range of 0.2–1000 Hz showed that the OA coating of the Fe3O4 nanoparticles leads to a spin-glass-like behavior credited to the strong particle-particle interactions; meanwhile, the double layer (AO + EO) coating of the Fe3O4 nanoparticles remarkably quenches the particle-particle interaction leading to a superparamagnetic-like behavior.