Controlled Synthesis, Characterization and Magnetic Properties of Magnetite (Fe₃O₄) Nanoparticles without Surfactant under N₂ Gas at Room Temperature

Abstract:

In this study, magnetite (Fe₃O₄) nanoparticles were synthesized at room temperature using FeCl₃.6H₂O (1.28 M), FeCl₂.4H₂O (0.64 M) and HCl (0.4 M) for preparing a solution as the iron source and NaOH (0.9-1.5 M) for to prepare a solution as the alkali source by the aqueous phase co-precipitation method under vigorous mechanical stirring (450 and 750 rpm) together with N₂ gas flowing through the reaction medium during synthesis operation in closed system. The powder samples were characterized by the commonly used techniques of scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infra-red (FTIR), X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and BET analyses. SEM was used to observe the morphology and agglomeration state of the powder. Size and morphology of the precipitated crystallites were examined with TEM. The prevalence of functional groups in the synthesized powders was ascertained by FTIR spectroscopy. The pure magnetite and other phases according to processing parameters were observed by XRD analysis. The magnetic properties of magnetite (Fe₃O₄) nanoparticles were examined using VSM. Finally, the specific surface area of nanoparticles was measured by BET technique. The results indicate that smaller particles can be synthesized by increasing stirring rate and decreasing the NaOH concentration, which in this case corresponded to 35 nm using 0.9 M NaOH at 750 rpm. The VSM analysis showed a saturation magnetization range of (82-96 emu/g) and coercivity of (83-119 Oe) for particles between (35-96 nm) respectively. Also, the highest specific surface area of 40 m²/g was obtained at 0.9 M NaOH at 750 rpm and the smallest value of 15 m²/g at 1.5 M of NaOH at 450 rpm using BET analysis.

• Periodical: Key Engineering Materials (Volumes 493-494)
• Pages: 746-751
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.493-494.746
• Online since: October 2011
• Authors: M. Raz, F. Moztarzadeh, A.Ansari Hamedani, Maziar Ashuri, M. Tahriri
• Keywords: Co-Precipitation Synthesis, Magnetite, Nanoparticle, Superparamagnetic

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