Abstract
Using non-isothermal thermogravimetry (TG), the oxidation kinetics of oxygen-deficient lithium-titanium ferrospinel, Li0.649Fe1.598Ti0.5Zn0.2Mn0.051O4-d, manufac- tured by ceramic engineering is investigated. The oxidation annealing of powder samples is performed in air. Accord- ing to the X-ray phase analysis, the processes giving rise to variations in oxygen content occur within single-phase spinel structure. The experimental kinetic results are pro- cessed using the Netzsch Thermokinetics software. The oxidation rate constants and the effective coefficients of atmospheric oxygen diffusion into the ferrites are deter- mined. The effective activation energy E of oxygen dif- fusion is found to be 1.95 eV. It is demonstrated that an increase in the oxygen non-stoichiometry parameter d as a result of recovery annealing of ferrite powders in vacuum at T = 1,070 K for 2 h gives rise to a slight decrease in E down to 1.89 eV. The activation energy of oxygen grain- boundary diffusion is identified by the electroconduction method. The resulting value 1.93 eV is fairly consistent with that obtained by TG.
Published Version
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