Thermal transformation of 1-(ferrocenyl)ethanol to iron oxide nanoparticles based on reaction atmosphere: analysis of the decomposition reaction using non-isothermal thermogravimetry

Thermal decomposition of 1-(ferrocenyl)ethanol was carried out under N 2 and O 2 atmospheres. Peak deconvolution method was used to separate the overlapped peaks and hence to obtain the temperature range of individual reactions. The decomposition followed two steps for N 2 atmosphere while for O 2 atmosphere three steps were observed. The integral iso-conversional methods (FWO, KAS, Tang, Starink, Vyazovkin and Akbi) were used to estimate the activation energy. The activation energies estimated are comparatively higher for FWO method in comparison to other methods while that estimated following other methods are quite close. Step-wise reaction mechanism functions have been determined. Simulated conversion plots were compared with the experimentally observed plots, and their close agreement implied the accuracy of the kinetic method adopted for analysis. Utilising the estimated kinetic parameters, thermodynamic parameters (Δ S , Δ H and Δ G ) were calculated. All estimated kinetic and thermodynamic parameters indicate the strong influence of gaseous medium used for solid state thermal decomposition. Thermally decomposed materials were characterized with powder XRD, SEM and EDX studies. From the characterization results it was concluded that thermal decomposition of 1-(ferrocenyl)ethanol led to the formation of nanocrystalline iron oxides only in oxidative atmosphere. It was proposed that at the initial state of decomposition magnetite might have formed as an intermediate which with increase of temperature first converted to maghemite and then gradually to hematite. The present study, through kinetic analysis and characterization of the decomposed materials, convincingly establishes the significant effect of the reaction atmosphere on the thermal decomposition of an organo-iron compound as well as the nature of the material produced.