Energy-dispersive surface X-ray scattering study of thin ceria overlayer on zirconia: Structural evolution with temperature

We have studied the structure of ultra-thin CeO2 overlayer on single crystals of Y stabilized cubic zirconia (ZrO2) by energy dispersive surface X-ray scattering. The overlayers were formed by depositing cerium metal and annealing in oxygen atmosphere. Three different crystallographic surfaces, (0 0 1), (0 1 1) and (1 1 1), were examined. We observed formation of CeO2 overlayer with thickness of 10–40 Å and lateral coherence length of 20–70 Å depending on the sample. In addition, we performed in situ temperature study of a sample with (0 0 1) surface. A zirconia crystal with cerium metal deposited on the surface was placed on a substrate heater and was annealed in air during in situ surface X-ray diffraction. We observed the formation of a ceria epitaxial film at 420°C followed by a preferential grain growth at higher temperatures and finally the diffusion of Ce into the bulk above 700°C.