Epitaxial growth of CeO2 thin film on cube textured NiW substrate using a propionate-based metalorganic deposition (MOD) method

The CeO2 films were epitaxially grown on (0 0 1)[1 0 0]Ni–W biaxially textured substrate using a propionate-based metalorganic deposition (MOD) method. The as deposited CeO2 films exhibit a sharp biaxial texture, with a full width at half maximum (FWHM) of φ and ω-scans of about 7.15° and 7.8°, respectively. The in-plane and out-of plane epitaxial relationship are [0 0 1]CeO2//[0 0 1]Ni–W and [1 0 0]CeO2//[1 1 0]Ni–W, respectively. The morphology of the films is strongly correlated with the film thickness and crystallization temperature. Thus, the 0.3 μm thick film crystallized at 1100 °C has a smooth surface free of cracks or voids with a root mean square roughness (RMS) of about 2.5 nm, whilst the 1.1 μm thick film presents many cracks and a low density of voids. The cracks along the substrate grain boundaries observed in the thicker films take place in the already crystallized film during the rapid cooling process due to difference between the thermal expansion coefficients of the film and metallic Ni–W substrate.