Formation and Structural Properties of Ce−Zr Mixed Oxide Nanotubes

In this work, ZrO 2 −CeO 2 mixed oxide nanotubes with 50, 70, and 90 mol % CeO 2 were synthesized following a very simple, high yield procedure, and their properties were characterized by synchrotron radiation XRD and by high resolution electron microscopy. The 50, 70, and 90 mol % CeO 2 nanotubes exhibited the tetragonal phase (t′-form and t′′-form, P 4 2 / nmc space group) or the cubic phase ( Fm 3 m space group). The nanotube walls were composed of nanoparticles with an average crystallite size ranging from 4.7 to 7.6 nm. Electron microscopy observations confirmed the size of these nanoparticles by direct observation. The SEM and TEM results showed that individual nanotubes were composed of a curved sheet of these nanoparticles. By SEM analysis, the nanotubes were found to have lengths of around 1−8 μm, diameters of around 500 nm, and wall thicknesses of 20 nm. Elemental analysis showed that Ce:Zr ratios appeared to be constant across space, suggesting compositional homogeneity in the samples. The 90 mol % CeO 2 nanotubes exhibited the highest value of specific surface area, 101 m 2 ·g −1, which compared with about 28 m 2 ·g −1 for the other two compositions.