Thermal Decomposition Study of Ferrocene [(C5H5)2Fe]

A single-step thermal decomposition of ferrocene [(C5H5)2Fe] using nonisothermal thermogravimetry (TG) has been studied using single- as well as multiple-heating rate programs. Both mechanistic and nonmechanistic methods have been used to analyze the TG data to estimate the kinetic parameters for the solid state reaction. Two different isoconversional methods (improved iterative method and model-free method) have been employed to analyze the TG results to find out whether the activation energy of the reaction depends on the extent of decomposition and to predict the most probable reaction mechanism of thermal decomposition as well. A comparison of the activation energy values for the single-step thermal reaction of ferrocene estimated by different methods has been made in this work. An appraisal on the applicability of single-heating rate data for the analysis of single-step thermal decompositions over the recommendations by the International Confederation for Thermal Analysis and Calorimetry (ICTAC) is made to look beyond the choice. 1. Introduction In recent times, the organometallic compound ferrocene, [(C5H5)2Fe], has become an important precursor material for preparing iron oxide nanostructures through thermal decomposition, for example, ferromagnetic micro/nanoparticles [1–3], iron oxide thin films [4], and single-walled/ferromagnetic-filled carbon nanotube [5, 6]. Taking leaf out of these works, we undertake to study the thermal decomposition of ferrocene materials in the presence of guest molecules of various kinds leading to iron oxides and to investigate the correlation among the thermal decomposition reaction kinetics, morphology/physical characteristics of the reaction products, and the nature of the guest molecules. As a prerequisite, we undertake to study the kinetics of thermal decomposition reaction of one such precursor material, ferrocene, in order to find the reaction kinetic parameters as well as the most probable mechanism. To the best of our knowledge there is only one report on the thermal decomposition study of ferrocene [7], which, however, does not discuss the reaction mechanism. There are two basic approaches to determine the reaction kinetic parameters or kinetic triplets (activation energy, frequency factor or rate of reaction, and most probable reaction mechanism function ) related to thermal decomposition using the thermogravimetry (TG) data—(a) mechanistic and (b) nonmechanistic [8]. At the beginning of the present TG data analysis we have utilized the well-known classic equations of Freeman-Carroll [9], Kissinger [10],