Abstract

The subject of research of this dissertation are cobalt oxides with a double perovskite structure with a general formula BaLnCo2O6-δ, where Ln stands for La, Pr, Nd, Sm, Gd, Tb, Dy. The aim of the study was to verify the ability of these materials to form the protonic defects, as well as to identify the factors determining this ability. As part of the work, materials from the proposed group were synthesised and characterized. To verify the research hypotheses the following techniques were used: powder x-ray diffraction, synchrotron radiation x-ray diffraction, powder neutron diffraction, scanning and transmission electron microscopy, thermogravimetry, iodometric titration, and x-ray absorption spectroscopy. The increase in mass in the atmosphere containing water vapour, which may indicate the incorporation of protonic defects into the material structure, was observed only in BaLaCo2O6-δ i BaGdCo2O6-δ. It has also been shown that this effect is not related to the existence or formation of secondary phases. It was observed that the factor determining the material's ability to form the protonic defects is the electronic structure of the material, resulting from the interaction between the lanthanide 4f orbitals, and the 3d cobalt and 2p oxygen orbitals.

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