Tuning silicon tetrachloride hydrolysis to optimize silica microstructure and sintering densification

• Tuning the SiCl 4 /H 2 O molar ratio ( R ) produces SiO 2 precursors whose microstructures transform from irregular agglomerates to interconnected frameworks as water content increases. • Surface area, pore distribution and mechanical properties of SiO 2 samples across different R values reveal that sintering‑driven microstructural evolution enhances optical transmittance and Vickers hardness . • Comparing pre‑ and post‑sintering densification for SiO 2 precursors with varying R values establishes how initial morphology dictates final densification behavior. Fused silica (SiO 2 ) glass is integral to numerous industries owing to its exceptional physical and chemical attributes. Although the hydrolysis of silicon tetrachloride (SiCl 4 ) provides a cost-effective and straightforward route for SiO 2 production, its influence on sintering densification and the underlying mechanisms remains poorly understood. Here, amorphous SiO 2 is prepared by hydrolyzing liquid SiCl 4 at different molar ratios of SiCl 4 to water ( R (SiCl 4 /H 2 O)). As the concentration of H 2 O increases, the SiO 2 specific surface area increases, and the microstructure evolves from agglomerated blocks into a connected skeleton. Sintering these hydrolyzed green samples significantly enhances their bulk density, reaching a maximum of 1.591 g/cm 3 at R = 1:70. Further analysis of the sintering activation energy reveals that this ratio also yields the lowest activation energy (34.439 kJ/mol), pinpointing the optimal conditions for achieving dense amorphous SiO 2 . Additionally, the influence of different microstructures on sintering densification is clarified.