Synthesis of a Flaky CeO₂ with Nanocrystals Used for Polishing

It is important to adapt the morphology of CeO₂ to different applications. A novel flaky CeO₂ with nanocrystals was successfully synthesized using the ordinal precipitation method and calcination. The size of the flaky CeO₂ was about 10 μm, and the nanocrystals were about 100 nm. Under the action of the precipitant NH₄HCO₃, Ce³⁺ nucleated in large quantities. The nanosized crystals gathered into flakes driven by the surface energy. As the calcination temperature increased, the grains grew slowly by mass transfer due to the slow diffusion of reactants. By adding AlOOH to the starting material, the Al³⁺ doped into the CeO₂ increased the content of Ce³⁺ in the CeO₂, which improved the chemical activity of the CeO₂. When the starting material's Al:Ce ratio was 5:1, the Ce³⁺ increased to 31.11% in the CeO₂, which provided good application potential in the polishing field. After polishing by the slurry of flaky CeO₂ for 1 h, the SiC surface roughness reduced from 464 nm to 11 nm.