Enhancing the Polishing Efficiency of CeO₂ Abrasives on the SiO₂ Substrates by Improving the Ce³⁺ Concentration on Their Surface

The polishing activity of CeO2 abrasives is enhanced by improving the Ce3+ concentration on their surface. In this study, a series of Ce1–xLaxO2 abrasives with different La3+ doping were prepared. The abrasives were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The effects of La3+ doping on the morphology, size, and Ce3+ concentration of the abrasives were studied. The morphology of the particles changes from sphere to octahedron with the La3+ doping. The lattice expansion of the CeO2 crystal after La3+ doping also significantly improves the Ce3+ concentration on the abrasive surface. However, the Ce3+ concentration on the surface gradually became saturated when the x was 0.2 or more. The polishing performance proved that the material removal rate (MRR) is closely related to the Ce3+ concentration generated by La3+ doping. The MRR of pure CeO2 abrasives with a Ce3+ concentration of 20.53% on a SiO2 substrate is 59.31 nm/min, while the Ce0.7La0.3O2 abrasives with the Ce3+ concentration increased to 34.41% achieved 101.12 nm/min. The polished surface quality was characterized by atomic force microscopy, which shows improved roughness of all samples. Furthermore, the differences in the removal rate of Ce3+ and Ce4+ in CeO2-based abrasives on the SiO2 substrate were also discussed.