Introduction of novel kinetic approach to calculation of activation energy and its application to the sinter-crystallization of strontian feldspar
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Date
2016-11-05
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Mark
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Elsevier
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Abstract
The kinetics, the mechanism and the thermodynamics of activated state of formation of primary strontian feldspar via sinter-crystallization of non-equilibrium melt during the thermal treatment of ceramic body was investigated in this work via differential thermal analysis using isoconversional Kissinger kinetic equation. The process of formation of non-equilibrium melt and subsequent crystallization of primary strontian feldspar requires the activation energy of 631±3 and 664±2 kJ mol1, respectively. The investigation of mechanism of formation of primary strontian feldspar reveals that the process is driven by the surface nucleation and diffusion controlled growth of the new phase. The nucleation rate decreases with the time of process and non-equilibrium melt can be formed only in metastable equilibrium with activated state of strontian feldspar. Deep consideration of kinetic data leads to the deduction of new kinetic approach that enables single calculation of activation energy and frequency factor of heterogeneous processes as well as the dependence of thermodynamic parameters of activated state on temperature. Further consideration of kinetic data reveals that the activation energy is directly proportional to the function of csch (z)+1. For z=e, this term enables to derive the value for the parameter B(x) in empirical equation for Arrhenius temperature integral p(x) proposed by Doyle to be 1.0642.
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Ceramics International. 2016, vol. 42, issue 15, p. 16969-16980.
http://www.sciencedirect.com/science/article/pii/S0272884216312792
http://www.sciencedirect.com/science/article/pii/S0272884216312792
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Peer-reviewed
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en