Preparation of CoXFe3–XO4 Oxydic System Starting from Metal Nitrates and Propanediol

This paper presents a study on preparation of the oxydic system CoxFe3–xO4 (x = 0,5; 1,0; 1,5) as nanoparticles starting from metalic nitrates (Co(NO3)2 • 6H2O, Fe(NO3)3 • 9H2O) and diols: 1,2 propanediol (OHCH2CH(OH)CH3) and 1,3 propanediol (OH(CH2)3OH). During the heating of metal nitrates – diol solution, a redox reaction took place between NO3 – anion and polyol, when –CH2–OH was oxidized at –COO–. The carboxylate anions, which resulted in the redox reaction, reacted with Co(II) and Fe(III) cations to form coordinative compounds, that were used as precursors for the CoxFe3–xO4 oxide system. DTA curves of the solutions Co(NO3)2 • 6H2O, Fe(NO3)3 • 9H2O – diol, showed two exothermic heat effects: at ∼343 K, corresponding to the redox reaction Fe(NO3)3 – diol and at ∼_388 K, due to the redox reaction Co(NO3)2 – diol. As a result of these redox reactions, a homogenous mixture of Fe(III) and Co(II) carboxylate compounds was obtained. These oxides precursors have been characterized by thermal analysis and FT-IR spectrometry. By thermal decomposition of the synthesized precursors at ∼_573 K, followed by annealing at 673 K, 973 K and 1273 K, CoFe2O4 was obtained as single or predominant nanocrystalline phase depending on the x value, as evidenced by XRD analysis.