pH-driven interfacial bond dynamics enable high-efficiency low-damage polishing of fused silica with CeO2 based slurries

Abstract

Achieving atomic-level surface integrity while maintaining a high material removal rate (MRR) remains a fundamental challenge in the polishing of fused silica due to its high hardness and brittleness. This study establishes a novel mechanistic framework for understanding how pH-driven interfacial bond dynamics govern chemo-mechanical polishing processes. By integrating multiscale experimental characterization (XPS, FTIR, Raman spectroscopy) with ReaxFF molecular dynamics simulations, we demonstrate for the first time that the dynamic equilibrium between the formation and rupture of Ce–O–Si interfacial bonds directly control removal efficiency and surface quality. Alkaline conditions enhance OH^– activity, facilitating Si–O bond hydrolysis and stable Ce–O–Si linkage formation, resulting in the highest MRR (397.6 nm/min). Acidic environments promote citrate-mediated Ce³⁺ complexation and nanocluster dispersion, enabling a rolling mechanism that achieves ultra-smooth surfaces (Sq = 0.086 nm). In contrast, neutral pH conditions suffer from PEG adsorption blocking active sites, leading to a 62 % reduction in MRR relative to alkaline systems. A 12.2-fold increase in MRR compared to SiO₂ abrasives (32.67 nm/min) confirms that chemical interfacial dynamics, rather than mechanical abrasion alone, are critical to material removal. This fundamental advancement provides a broadly generalizable theoretical basis for designing efficient, low-damage precision polishing processes across oxide-based optical materials and beyond.