Application of simplified version of advanced isoconversional procedure in non-isothermal kinetic study

Abstract

The single phase NH4Co0.9Zn0.1PO4·H2O was prepared via solid-state reaction at 80 °C. Based on a simplified version of advanced isoconversional procedure, the values of activation energy Eα associated with the first, second, and third stages of the thermal decomposition of NH4Co0.9Zn0.1PO4·H2O were obtained, which demonstrates that the third stage is a kinetically complex process, and the first and second stages are single-step kinetic processes and can be described by a unique kinetic triplet [Eα, A, and g(α)]. The most probable reaction mechanisms of the first two stages were estimated by the comparison between experimental plots and modeled results. The values of pre-exponential factor A of the two stages were obtained on the basis of Eα and the reaction mechanisms. The distributed activation energy model was applied to study the third stage. Besides, some thermodynamic functions of transition state complexes (ΔS≠, ΔH≠, and ΔG≠) of the two stages were also calculated.