The Research On The Microstructure Of CaBaCo₂O_5+? Thin Films As Cathode Material For Solid Oxide Fuel Cell

Solid oxide fuel cell?SOFC? is a high-efficient and environment-friendly energy device, whereas the realization of medium and low temperature is the major research direction in this field. However, during this process, a series of problem s concerning polarization loss resulted from excessive cathode material seriously influence the property of SOFC, and they become the main obstacles in realizing the commercialization of SOFC. As a kind of cathode material, Oxide with perovskite structure has favorable ion-electron conductivity, oxygenic catalytic activity and chemical stability, moreover it is low cost. AA'B2O5+? oxide cathode material with double perovskite structure distributes in a highly ordered way in A position, which is beneficial to the diffusion of oxygen ions and the exchange of oxygen. Meanwhile, such oxides have higher conductivity in medium and low temperature, which enables them to become promising SOFC cathode material in medium and low temperature.In the paper, our research object is focused on the cathode film material Ca Ba Co₂O_5+??CBCO? of cobalt-based double perovskite structure SOFC. CBCO film on La Al O3?LAO? substrate was successfully prepared by means of pulsed laser deposition method. X-ray diffraction?XRD? and scanning electron microscope?SEM? were used for characterization. More importantly, the transmission electron microscope?T EM? that was rarely applied in the related researches was used as the main characterization means of research material microstructure. T EM sample was successfully prepared by using ion thinning method and focused ion beam?FIB? method. T he crystal cell paramete rs of CBCO film were analyzed and calculated. Besides, the microstructure of CBCO film, LAO substrate and the junction between film and substrate were observed. Finally, the following conclusions were drawn:?1? CBCO film was composed of porous film that was of good granular density and connectivity.?2? CBCO film was polycrystalline film. Starting from the place next to LAO substrate, the grain size in CBCO film increased gradually from a few nanometers to tens of nanometers with the increase of film thickness.?3? The observation from the different orientations and regions of LAO substrate showed that there was no epitaxial relationship between CBCO film and LAO substrate. There were defects in LAO substrate. In addition, the LAO substrate surface in the junction of CBCO film and LAO substrate was not smooth at the atomic level and atomic steps existed. Both the defects in LAO substrate and the uneven surface of LAO substrate affected the depositional CBCO film.The studies have been introduce d the microstructure as well as their relationship with the growth mechanism of CBCO film, which gives useful information to improve the cathode performance.