Studies of Oxygen Deficient Complex Cobaltates with Perovskite Related Structures
The present thesis deals with the investigation of some perovskite related complex cobaltates. The phases Sr2Co2-xGaxO5 (0.3 ? x ? 0.7), Sr2Co2-xAlxO5 (0.3 ? x ? 0.5), Sr1-xBixCoO3-y (0.1 ? x ? 0.2), Sr0.75Y0.25Co1-xGaxO2.625 (0.125 ? x ? 0.375) and Sr0.75Y0.25Co1-xFexO2.625+? (0.125 ? x ? 0.625) were synthesised and characterised. All these compounds crystallises with similar structures, they are all composed by altering layers of octahedra and tetrahedra although in the two former, the tetrahedra are organised in chains (the Brownmillerite structure), while in the latter three the tetrahedra arranges as segregated Co4O12 units (the 314 type structure). The techniques X-ray and neutron diffraction, transmission electron microscopy, thermal analysis and magnetic measurements were used to track structural and important physical properties.
Source Type:Doctoral Dissertation
Date of Publication:01/01/2006