In this study, the thermal stability and decomposition kinetics of Hägg iron carbide nanoparticles synthesized via a wet chemical method have been investigated. Results of Mössbauer spectroscopy were in consonance with x-ray diffraction to prove the formation of Fe5C2 nanoparticles. The activation energy of the transformation was evaluated by thermogravimetric analysis, performed at different heating rates from room tempearture to 573 K, employing the Flynn-Wall-Ozawa and Coats-Redfern models. Using the Criado model, degradation kinetics was determined to be a three-dimensional diffusion type. Thermal x-ray analysis, high resolution transmission electron microscopy, and vibrating sample magnometer measurements were performed both before and after thermal treatment of the nanoparticles to compare phase structure, morphology, and magnetic properties. Results show that the high magnetic, high density Hägg iron carbide with a core-shell structure converts to the lower density magnetite with moderate magnetization and core shell structure.

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