CTAB-assisted hydrothermal synthesis of NiFe2O4 and its magnetic characterization

A simple hydrothermal route is demonstrated for the synthesis of nickel ferrite nanocrystals, NiFe2O4, using cetyltrimethylammonium bromide (CTAB) as the surfactant and NH3 and NaOH as hydrolyzing agents. Synthesized materials have been characterized by XRD, FTIR, ESR, and TEM techniques. It was found that crystallization in both hydrolyzing agent led to nanometric in size. Average particle size of prepared samples was calculated from TEM micrographs and varied significantly between samples prepared using different hydrolyzing agents; it was ∼12 nm when conc. NH3 was used and ∼50 nm when 2 M NaOH was used. Crystallite size obtained using Scherrer equation agreed well with the TEM observations with the respective values of 15 and 55 nm. ESR analysis showed single broad bands which might indicate the phase homogeneity of the materials. Furthermore, linewidths were observed to differ due to the difference in magnetization that depends on the particle size; NiFe2O4 sample hydrolysed with NH3 has a larger linewidth revealing its smaller particle size as confirmed by XRD and TEM techniques.