Study on the formation of CoxFe3−xO4 system using two low temperature synthesis methods

This paper presents a study regarding the cobalt ferrite obtaining in the CoxFe3−xO4 system, where x = 0.5; 1.0; 1.5 by two different synthesis methods. The Co(II) and Fe(III) complexes method leads to the thermal decomposition at 300 °C for this precursor with the pure cobalt ferrite (CoFe2O4) formation for x = 1 or mixed with γ-Fe2O3 for x = 0.5 and Co3O4 for x = 1.5. By co-precipitation followed by ultrasonic milling synthesis method the pure cobalt ferrite is obtained at 90 °C for x = 1 or mixed with Fe3O4 for x = 0.5 and Co3O4 for x = 1.5. When the initial samples are heated at 400 °C, the identified oxide phase is identical for the same value of x. The obtained powders were investigated by X-ray diffraction (XRD), FTIR spectrometry and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDX). The final product has nanometric size and has a strong tendency to agglomerated, thus influencing the saturation magnetization value. The shape of the magnetization curves is influenced by the presence of the secondary phases for x ≠ 1.

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► CoxFe3−xO4 nanopowders are synthesized by two synthesis methods.
► The thermal decomposition of mixed Fe(III), Co(II) carboxylates method is original.
► For x = 1.0, CoFe2O4 crystallizes as single phase at low temperatures by both methods.
► The presence of secondary phases for x ≠ 1 influences the magnetic properties.
► The particles are nanosized (<50 nm) leading to sintering at lower temperatures.