Effect of fatty acid chain length and concentration on the structural properties of the coated CoFe2O4 nanoparticles

• Effects of fatty acid chain length on the coating of CoFe2O4 nanoparticles were studied.
• Crystallite size increases from 16.75 to 24.51 nm when temperature changes 27–80 °C.
• Aggregation of nanoparticles were reduced as the concentration of oleic acid increased.
• Fatty acid coated nanoparticles exhibit ferromagnetic nature.
• Oleic acid enhances the suspension stability of CoFe2O4 in aqueous medium over 168 h.

The present study investigates the effect of various synthesis parameters including chain length of fatty acids, concentration ratio of precursor to fatty acid, reaction temperature and aging time on the structural as well as magnetic properties of the CoFe2O4 nanoparticles. The synthesis of nanoparticles was achieved successfully in aqueous solution by the conventional Co-precipitation technique using Fe3+ and Co2+ ions by the addition of a strong base NaOH. Herein, the Oleic acid and Lauric acid was used as the stabilizing agent during the nucleation stage of the nanoparticles. The structural as well as morphological properties were characterized by XRD, FTIR and FESEM techniques and the magnetic intensity was investigated by vibrational sample magnetometer (VSM). The XRD analysis of the coated nanoparticles confirmed that the cubic spinel phase of the CoFe2O4 nanoparticles were retained after coating and the crystallite size reduced as the concentration of fatty acid increased. FESEM analysis revealed that the synthesized nanoparticles were of spherical shape and the extent of nanoparticle aggregation reduced gradually as the ratio of precursor to oleic acid was decreased from 4 to 1. Further, the hysteresis loop confirmed the ferromagnetic nature of the coated nanoparticles with high coercivity.

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