Cobalt ferrite nanoparticles synthesis by sol–gel auto-combustion method in the presence of agarose: a non-isothermal kinetic analysis

In this study, cobalt ferrite (CoFe2O4) nanoparticles were synthesized by sol–gel auto-combustion technique in the presence of agarose as a natural gelling agent, and its influence on the morphology and magnetic properties of CoFe2O4 as well as kinetic parameters of their synthesis was investigated. The synthesized samples were characterized by TG–DTA, XRD, FTIR, FE-SEM, and VSM. A highly crystalized CoFe2O4 with a spinel structure was obtained by calcination at 1073 K for three hours. The agarose acted as a chelating and templating agent during the formation of CoFe2O4 nanoparticles, so that it showed a significant effect not only on decreasing agglomeration but also on reducing crystallite size from 70.3 to 54.6 nm. The VSM results revealed that coercivity increased from 818 to 1076 Oe by agarose addition. Furthermore, the effect of adding agarose on the kinetic parameters and formation mechanism of CoFe2O4 nanoparticles during the calcination process under a non-isothermal condition was investigated by differential thermal analysis (DTA). The results showed that agarose reduces the activation energy in CoFe2O4 formation during the calcination process from 143.9 to 64.33 kJ mol−1. Moreover, the mechanism of this process was changed after agarose addition from Avrami–Erofeev models (A) to the phase boundary reaction (R). Overall, these results demonstrated the positive effect of agarose on the nucleation of cobalt ferrite nanoparticles.