Fused silica with sub‐angstrom roughness and minimal surface defects polished by ultrafine nano‐CeO2

Abstract Surface quality of fused silica, particularly surface defect and surface roughness, is a key factor affecting the performance of high‐power laser and short‐wave optical instrument, and so on. Herein, the super smooth surface of fused silica with roughness of sub‐angstrom level and exceedingly few submicron defects was achieved by using ultrafine nano‐CeO 2 with primary particle size less than 4 nm, low secondary particle agglomeration strength, and high Ce 3+ concentration. Furthermore, CeO 2 involve in polishing process in the form of primary particle was certified by experiment. Moreover, the cause for the generation of submicron defects on fused silica surface was investigated for the first time from the perspective of secondary particle agglomeration strength of CeO 2 . The concentration of Ce 3+ in CeO 2 was characterized by the redshift of the band‐gap energy, and the analysis of material removal rate (MRR) and contact angle of polished fused silica shows that Ce 3+ enhances MRR through increasing the silanol group on fused silica.