Sol-gel route to porous lanthanum cobaltite (LaCoO3) thin films

Sol-gel-derived LaCoO3 thin films were deposited on yttria-stabilized zirco nia (YSZ) substrates from a lanthanum isopropoxide-cobalt acetate (with 2-m ethoxyethanol) precursor solution. A chelating agent (2-ethylacetoacetate) and polyethylene glycol (PEG) were used to modify the above-mentioned precu rsor solution. The La-Co precursor solution was sufficiently viscous, and t ransparent LaCoO3 gel films were prepared successfully using a spin-coating technique. Crystallization behavior and microstructure evolution were inve stigated using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). A single-phase perovskite thin film with the grain size of similar t o 50 nm was obtained by heat-treating the spin-coated gel film at a tempera ture of 600 degreesC. SEM observations revealed that the microstructure of LaCoO3 thin films that were prepared from the precursor solution with PEG w as porous, and the LaCoO3 thin film maintained its porous microstructure to a temperature of 800 degreesC.