Physical Properties of Ceria Particles

FIGURE 3.4 X-ray diffraction pattern of Ce02 powders synthesized by precipitation method. 

Average crystallite size of Ce02 calculated by the Scherrer equation from the XRD line broadening was 46 nm for powder A and 34 nm for powder B. The crystallite size increases as the calcined temperature increases. 

---

The size and shape of ceria NCs are proven fo appreciably change the chemical and physical properties hence, their control in synthesis is one chief objective for study, and various nanoparticles, nanocubes, nanooc-tahedra, nanowires, and nanotubes have been obtained for this purpose. Owing to the cubic fluorite structure, ceria tends to form isometric particles, which present sphere-like morphology and are usually intermediates between the shape of cubes and octahedra. The major exposed crystal surfaces for ceria NCs are low index ones, that is, 100, llOj, and 111, with considerable surface relaxation and reconstructions. Figure 1 shows some typical morphologies of ceria NCs. 

Based on long experience of Rare Earths technology, it becomes possible to design ceria powders with proper physical properties for polishing applications, namely hardness, morphology and particle size distribution as shown in Figure 9-20. 

---