Dependence of pH and surfactant effect in the synthesis of magnetite (Fe 3O 4) nanoparticles and its properties

• Published in: Journal of magnetism and magnetic materials 2010-02, Vol.322 (4), p.400-404
• Main Authors: Faiyas, A.P.A., Vinod, E.M., Joseph, J., Ganesan, R., Pandey, R.K.
• Format: Article
• Language: English
• Subjects: Chemical synthesis methods; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Magnetic nanoparticles; Magnetic properties and materials; Magnetic properties of nanostructures; Materials science; Methods of nanofabrication; Nanopowders; Nanoscale materials and structures: fabrication and characterization; pH value; Physics; XPS; XRD
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2009.09.064

Nanoparticles of Fe 3O 4 were synthesized by co-precipitation in an aqueous solution containing ferrous and ferric salts (1:2) at varying pH with ammonia as a base. It was found that the value of pH influences the reaction mechanism for the formation of Fe 3O 4. Furthermore, the addition of mercaptoethanol significantly reduced the crystalline size of Fe 3O 4 nanoparticles from 15.03 to 8.02 nm. X-ray diffraction (XRD) spectra revealed that the synthesized nanoparticles were ε-Fe 2O 3 or Fe 3O 4 phase. To further prove the composition of the product, as-prepared Fe 3O 4 were examined by X-ray photoelectron spectroscopy (XPS). Magnetic properties of the obtained particles were determined by vibrating sample magnetometer (VSM). Further analysis of the X-ray studies shows that while maintaining a pH value of 6 and 9 in a solution containing iron salts II and III ions produces ε-Fe 2O 3. Whereas a pH value of 11 produces magnetite (Fe 3O 4) phase. All of these results show that the pH has a major role in the observed phase formation of (Fe 3O 4) nanoparticles.