<p>As a crucial abrasive in chemical mechanical polishing (CMP), ceria has garnered significant attention regarding its preparation method and surface modification methods. This research investigates the properties for samarium-doped ceria nanospheres prepared via the solvothermal method and their CMP performance on dielectric materials. Ceria nanospheres with various Sm doping concentrations were synthesized using a surfactant-assisted solvothermal method. Doping increased the ratio of Ce³⁺ to Ce⁴⁺ and oxygen vacancy in ceria. While, Sm doping reduced the overall amount of Ce, resulting in a decrease in the material removal rate (MRR) of silicon oxide, and an initial decrease followed by an increase in the MRR of silicon nitride. The Ce_0.95Sm_0.05O₂ suspension exhibited better material removal selectivity than pristine ceria nanospheres, with an increase in the selection ratio from 7:1 to 25:1.</p> Graphical Abstract <p></p>