Fabrication of silica glass for UV-transmission by gel-casting method

Abstract

We present the gel casting preparation of sintered silica glass and analyze its structural and optical properties in both atmospheric and 10−4 Pa high-vacuum conditions, with annealed and non-annealed samples, alongside a comparison to synthetic silica glass. The crystallization temperature of SiO2 bodies sintered in high-vacuum is higher than that in atmosphere since high-vacuum sintered body has less β-OH, the suitable temperature range is on the high temperature side compared to in the atmosphere. Fluorescence spectrum, ESR spectra and the transmittance spectrum indicate the existence of NBOHC, POR and E′ center in atmospheric sintered silica glass as well as ODC(I) and E′ center in high-vacuum sintered silica glass. High-vacuum sintering and annealing in hydrogen atmosphere can eliminate oxygen defects, NBOHC, POR, and E’ centers, resulting in the transmittance reached 91.1 % at 265 nm and 87.3 % at 230 nm. These are equivalent to 98.9 % and 94.9 % of the synthetic silica glass, respectively.