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2 Polish Journal of Chemistry

2 2009

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Oxygen Nonstoichiometry and Transport Properties of Selected La1-xSrxCo1-y-zFeyNizO3-delta Perovskites

Świerczek K.

Polish Journal of Chemistry

2009

Vol. 83, nr 8

1437-1442

Crystal structure, high temperature oxygen nonstoichiometry and transport properties of two members of La1-xSrxCo1-y-zFeyNizO3-delta group of perovskite type oxides are presented. La0.6Sr0.4Co0.2Fe0.6Ni0.2O3-delta and La0.9Sr0.1Co1/3Fe1/3Ni1/3O3-delta compositions po sess high electrical conductivity at high temperatures in air. How ever, the observed characteristics of the electrical conductivity as a function of the oxygen partial pressure for these materials are significantly different. A discussion of the observed effects is provided, which shows strong correlation between chemical composition, crystal structure, oxygen nonstoichiometry and the observed transport properties. An interesting phenomenon related to an irreversible oxygenation of the quenched La0.6Sr0.4Co0.2Fe0.6Ni0.2O3-delta samples was observed. This reaction takes place at 200–300 graduate C range which is well below a typical nonstoichiometry related reactions. A possible explanation of this effect is discussed.

Chemical Diffusion in Sr(Ce1-xYx)O3–delta

Pasierb P., Filipek R., Rekas M.

Polish Journal of Chemistry

2009

Vol. 83, nr 8

1443-1454

Ceramic Sr(Ce0.95Y0.05)O3-delta was equilibrated at an ambient air (either wet or dry) and Ar-H2 atmospheres. After the step change of gas atmosphere, the equilibration kinetics was monitored by measuring weight change. Fick’s second law was applied to the experimental kinetic data (the in verse method) to obtain the chemical diffusion coefficient, Dchem. The determined Dchem indicates the complex processes in volving creation and transport of both oxygen vacancies and protonic defects in the studied material.