Deposition of SDC and NiO-SDC thin films and their surface morphology control by electrostatic spray deposition

The deposition of samaria-doped ceria (SDC, Sm0.2Ce0.8Ox) and NiO-SDC thin films on a SDC substrate was studied using the electrostatic spray deposition (ESD) technique. The precursor solution was prepared by dissolving the correct amount of Sm(NO3)(3)center dot 6H(2)O, Ce(NO3)(3)center dot 6H(2)O and Ni(NO3)(2)center dot 6H(2)O into a mixture of ethanol (C2H5OH) and butyl carbitol (C4H9OC2H4OC2H4OH). The surface microstructure of as-deposited thin films was strongly influenced by the substrate temperature, solvent composition and precursor solution. The reticular film of SDC with high porosity could be successfully prepared at the deposition temperature ranging from 300 to 350 degrees C, a precursor solution of 0.005 mol/dm(3) and a 50 vol.% of butyl carbital. The correlations between the surface morphology of as-deposited thin films and the physical properties of precursor solution could be approximately explained by the following equation [21]: d = G(epsilon) (epsilon epsilon(0) Q/K)(1/3) where d is the size of sprayed droplet, Q the flow rate of liquid pushed through the jet, epsilon the dielectric constant of liquid, epsilon(0) the electrical permittivity of vacuum, and G(epsilon) is the function of epsilon. The as-deposited thin films were amorphous at the used deposition temperature (350 degrees C). Subsequently, the thermal treatments were done for ranging from 700 to 900 degrees C in air. As the result, the crystal structure transformed into the desired cubic fluorite one after the sample was annealed over 700 degrees C in the as-deposited SDC thin films and 900 degrees C in the as-deposited NiO-SDC thin films, respectively. To confirm the composition of the as-sintered SDC thin films, ICP-OES analysis was studied for the films annealed at 900 degrees C in air for 2 h. The observed chemical composition was found to be close to that of the precursor solution within experimental errors. (C) 2007 Elsevier B.V. All rights reserved.