A single-step thermal decomposition of ferrocene [(C 5 H 5 ) 2 Fe] 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.

The paper deals with the thermal decomposition of organometallic compound ferrocene carboxaldehyde [(C5H4CHO)Fe(C5H5)] in oxidative atmosphere, which leads to pure hematite nanoparticles, studied with non-isothermal thermogravimetry (TG) protocol. Deconvolution method with Fraser-Suzuki fit function is adopted to resolve the complex multistep TG profiles into six different reaction steps. Step-wise reaction kinetic parameters (activation energy, reaction mechanism function, reaction rate) are estimated based on the mathematical analysis of the multi-heating rate TG data primarily following model-free (integral isoconversional) approach and using master-plot method. The estimated kinetic parameters are utilised to reconstruct the conversion plots which successfully resemble the experimentally observed ones. A plausible reaction process leading to hematite on thermal decomposition of ferrocene carboxaldehyde as the end product is discussed. A comparative discussion on the thermal decomposition of two ferrocene derivatives have been made. The novelty of the present work lies in successful deconvolution of complex TG profiles and hence obtaining the step-wise reaction kinetic parameters demonstrating different reaction mechanisms involved in the thermal synthesis of hematite nanoparticles starting from ferrocene carboxaldehyde which have no prior reporting. Further, a satisfactory agreement between the reconstructed and experimental decomposition profiles establishes the correctness of the applied modelling approach as well as the methodology adopted.

No abstract

No abstract

The dark conduction properties of ferrocenedicarboxylic acid have been studied as a function of voltage at different sample-temperatures by using sandwich type of cell configuration. The analysis of the results was based on the space charge limited conduction (SCLC) theory. The trap distribution in this material has been found to be exponential type as was observed in case of ferrocene and ferrocenecarboxylic acid. The dark activation energy (ohmic) of these ferrocene derivatives increases with the gradual substitution of –COOH group in the ferrocene ring system. In contrast to the nonextrinsic nature of ferrocenecarboxylic acid, ferrocenedicarboxylic acid has been observed to be extrinsic, similar to ferrocene. The photoconductivity in these materials was studied as a function of temperature and the intensity of exciting light source. The distribution of traps in these materials has been determined from the intensity dependence of photocurrent and these results have been compared with the results of dark conductivity measurements.