Sol–Gel Route to Porous Lanthanum Cobaltite (LaCoO 3 ) Thin Films

Sol–gel‐derived LaCoO 3 thin films were deposited on yttria‐stabilized zirconia (YSZ) substrates from a lanthanum isopropoxide–cobalt acetate (with 2‐methoxyethanol) precursor solution. A chelating agent (2‐ethylacetoacetate) and polyethylene glycol (PEG) were used to modify the above‐mentioned precursor solution. The La‐Co precursor solution was sufficiently viscous, and transparent LaCoO 3 gel films were prepared successfully using a spin‐coating technique. Crystallization behavior and microstructure evolution were investigated using X‐ray diffractometry (XRD) and scanning electron microscopy (SEM). A single‐phase perovskite thin film with the grain size of ∼50 nm was obtained by heat‐treating the spin‐coated gel film at a temperature of 600°C. SEM observations revealed that the microstructure of LaCoO 3 thin films that were prepared from the precursor solution with PEG was porous, and the LaCoO 3 thin film maintained its porous microstructure to a temperature of 800°C.