Facet engineering of ceria and the preferential cleavage-consumption mechanism in chemical mechanical polishing

The rational design of high-performance ceria (CeO 2 ) polishing abrasives is largely constrained by the unclear correlation between crystal plane exposure, dynamic oxygen vacancy evolution, and the chemical-mechanical synergistic mechanism during chemical mechanical polishing (CMP). Herein, four morphology-controlled CeO 2 abrasives with dominantly exposed (200), (111), mixed (111)/(200), and (220) crystal planes were synthesized via a facile precipitation-hydrothermal method. Through K9 glass polishing tests, we innovatively reveal the "Preferential Cleavage and Dynamic Consumption" synergistic cycle mechanism in CeO 2 CMP.XPS results show that the Ce 3+ content of all four abrasives increased significantly to comparable levels after polishing. The increment of oxygen vacancy (O v ) concentration varied markedly among the samples, and exhibited a positive correlation with the material removal rate (MRR). For the (111)-dominant abrasive, the O v concentration increased from 21.37% to 48.57%, corresponding to the highest MRR of 204 nm/min. This confirms that oxygen vacancies are the decisive factor promoting the formation of Ce-O-Si chemical bridges. XRD results reveal that the (111) plane showed the most significant intensity attenuation after polishing, demonstrating the fracture priority order of CeO 2 under mechanical stress: {111} > {100} > {110}.Mechanical shear induces the preferential fracture of CeO 2 along the {111} plane, which generates fresh active surfaces and abundant O v to strengthen chemical bonding, thus forming a self-reinforcing chemical-mechanical synergistic cycle. This work provides direct theoretical guidance for the crystal plane-oriented design of high-efficiency, low-damage CeO 2 polishing abrasives.