Synthesis and properties of precipitated cobalt ferrite nanoparticles

Abstract

The formation and properties of cobalt ferrite were investigated with XRD, FT-IR, FE-SEM, MEuroossbauer and magnetometry. Cobalt ferrite samples were prepared (a) by combining coprecipitation Co(OH)2/2Fe(OH)3, using NaOH between pH 5.2 and 11.4 and autoclaving, and (b) by autoclaving the Co(OH)2/2Fe(OH)3 coprecipitate in a very strong alkaline medium. XRD and FE SEM showed that both CoFe2O4 crystallites and particles were in the nanosize range. The FT-IR spectra were typical of spinel ferrites. Cobalt ferrite precipitated at pH 7.2 and at 11.4 contained a small fraction of a-Fe2O3, whereas in the sample precipitated at pH 11.4 a very small amount (traces) of a-FeOOH were detected by FT-IR, additionally. Parameters obtained by MEuroossbauer spectroscopy suggested a structural migration of cobalt and iron ions in prepared cobalt ferrite spinels with the prolonged time of autoclaving. Magnetic measurements showed the magnetic behaviour typical of spinel ferrite nanoparticles.