Cross-sectional observation of yttrium and nickel oxide doped ceria powder

In this paper, microstructures of ceria powder, synthesized using spray pyrolysis method, were characterized by focused ion beam technique and transmission electron microscopy. Dependence of the shape of powder particle on the size was found. It appears a spherical shape with the diameter less than approximately 500 nm and shows cup-like shape when their diameters become larger as a result of concaving. This suggests that the spherical particle has a hollow structure as proved by focused ion beam cross-sectioning. It was also found that both the inner and the outer shells of particles are crystalline but comprised of different phases with the inner shell being NiO and the outer shell CeO2. These results benefit from a transmission electron microscopy sample preparation method to produce a cross-section of the particle. The detail of the method was described in the paper.