Influence of Co2+ Ion Concentration on the Size, Magnetic Properties, and Purity of CoFe2O4 Spinel Ferrite Nanoparticles

• Published in: Journal of physical chemistry. C 2010-04, Vol.114 (14), p.6334-6341
• Main Authors: Ayyappan, S, Mahadevan, S, Chandramohan, P, Srinivasan, M. P, Philip, John, Raj, Baldev
• Format: Article
• Language: English
• Subjects: C: Nanops and Nanostructures
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp911966p

Cobalt ferrite nanoparticles of different sizes are prepared by varying the concentration of Co2+ metal ions using precipitation approach. The average crystallite size, coercivity (H C), and saturation magnetization (M S) increases from 11 to 16 nm, 0.12 to 0.8 kOe, and 28 to 52 emu/g, respectively, as Co2+ ion concentration is reduced from 0.4 to 0.025 M. High resolution transmission electron microscopy and X-ray diffraction analysis confirms that CoFe2O4 nanoparticles are crystalline in nature with cubic structure. Raman spectroscopic investigation shows traces of paramagnetic ferrihydrite in samples prepared with Co2+ ion concentration greater than 0.1 M. These experimental results suggest that metal ion concentration plays an important role in the size, magnetic property and purity of precipitated cobalt ferrite nanoparticles. The variation in the average crystalline size with Co2+ ion concentration is in good agreement with the nucleation theory. Our approach is useful in tuning the size and magnetic properties of cobalt ferrite nanoparticles.