Study of the oxidation kinetics of finely-divided magnetites IV. Influence of zinc substitution |
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Authors: | Bernard Gillot Rida Mohamed Benloucif Abel Rousset |
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Affiliation: | Laboratoire de Recherches sur la Réactivité des Solides, associé au C.N.R.S. Faculté des Sciences Mirande, B.P. 138 - 21004 Dijon Cedex, France;Laboratoire de Chimie des Matériaux Inorganiques, Université Paul Sabatier Toulouse III, 118, route de Narbonne, 31000 Toulouse, France |
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Abstract: | The oxidation kinetics of zinc substituted magnetites (Fe2+1?xZn2+xFe3+2)O2?4 (O < x < 1) into the γ defect phase of type x(Zn2+Fe3+2O2?4), is found to be governed by the diffusion with a chemical diffusion coefficient depending on vacancy concentration. For compounds rich in zinc the diffusion coefficient is constant and the rate law written as v = k Pn(O2) with is in agreement with a partial association of defects. For low substitution extents the diffusion coefficient varies with the transformation extent α and exponent n from the pressure law is equal to , which agrees with a total association of defects. |
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