Nonstoichiometry and Chemical Diffusion in Co3O4 Cobalt Oxide

Zbigniew Grzesik; Anna Kaczmarska; Stanisław Mrowec

doi:10.4028/www.scientific.net/SSP.227.421

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HomeSolid State PhenomenaSolid State Phenomena Vol. 227Nonstoichiometry and Chemical Diffusion in Co3O4...

Nonstoichiometry and Chemical Diffusion in Co₃O₄ Cobalt Oxide

Abstract:

Nonstoichiometry and chemical diffusion in Co₃O₄ oxide have been studied as a function of temperature (973-1173 K) and oxygen pressure (30-10⁵ Pa), using thermogravimetric techniques. It has been found that at very low oxygen pressures, close to the dissociation pressure of the oxide, interstitial cations and quasi-free electrons are the predominant point defects, while at high pressures cation vacancies and electron holes predominate. This behaviour is reflected in complex dependence of the deviation from stoichiometry, y, in the Co_3±yO₄ oxide on oxygen pressure. At low pressures, namely, deviation from stoichiometry decreases with increasing oxygen pressure, reaching virtually constant value in intermediate pressures and increases at highest pressure range. Finally, these data as well as the results of kinetic rate measurements of Co_3±yO₄ formation have been utilized in calculating the chemical diffusion coefficient as a function of temperature.

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Solid State Phenomena (Volume 227)

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421-424

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https://doi.org/10.4028/www.scientific.net/SSP.227.421

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January 2015

Authors:

Zbigniew Grzesik*, Anna Kaczmarska, Stanisław Mrowec

Keywords:

Co₃O₄, Defect Concentration, Diffusion, Nonstoichiometry

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