New combination of non-isothermal kinetics-revealing methods: Study of Se90Te10 powders with heterogeneous particle sizes and shapes

This work introduces a new method of calculations depending on the essential assumptions of the kinetic methods, with the least amount of approximations to find the apparent kinetic parameters calculated for the crystallization of the Se90Te10 powders with heterogeneous particle sizes and shapes under non-isothermal conditions. The apparent kinetic parameters calculated by the new method are compared with that calculated blindly by applying Málek’s method, ignoring its applicability condition of invariant activation energy. The new method is based on the assumption that the kinetic function f(α) parameters are independent of the heating rate β and time t, and the fitting temperature function is assumed to be in the approximated form K(T) = K(t, β) = ctrβs. The exponents r and s are calculated isoconversionally, while the constant c and the kinetic function f(α) parameters are calculated by a curve fitting method using a generalized form of the Šesták and Berggren function, considering the steadily and logarithmic acceleration and deceleration of the curve. According to the data in this work, the fitting temperature function can be roughly approximated to the form K(T) ≈ c/ t which work in with the physical dimensions of the rate constant. Moreover, the Arrhenian and the non-Arrhenian parameters, which describe the fitting temperature function K(T) , are calculated isoconversionally. The deduced parameters work harmonically together to perfectly fit the experimental and the true data. © 2017, Akadémiai Kiadó, Budapest, Hungary.