Structural Properties and Ionic Conductivity of Ce0.8Gd0.2O2 and Ce0.8Sm0.2O2 Thin Films Grown by Pulsed Laser Deposition

Thin films of Ce0.8Gd0.2O2 and Ce0.8Sm0.2O2 oxide electrolytes have been fabricated by pulsed laser deposition on (100)LaAlO3 substrates at temperature from 300 °C to 700 °C and under 100 mTorr oxygen ambient pressure. The crystal structure, crystallinity and lattice parameters of the as-deposited films are investigated by X-ray diffraction. High quality epitaxial and polycrystalline films are obtained at different growth conditions. We have made impedance measurements on these films in the temperature range from 300 °C to 850 °C. Our results reveal a mark increase in the ionic conductivity of these films in comparison with those of the corresponding bulk materials. The observed enhancements are closely related to the crystallinity of the films. Conductivities of 0.1 S/cm or higher for Ce0.8Gd0.2O2 and Ce0.8Sm0.2O2 are obtained at 500 °C. We have demonstrated that in utilizing these thin films solid oxide fuel cells operating at below 500 °C are possible.