Preparation of SiO2-PVA nanocomposite and monolithic transparent silica glass by sintering

We present a procedure for fabricating transparent silica glass that involves the sintering of green bodies prepared from an inorganic–organic nanocomposite. The nanocomposite was prepared from fumed silica and poly(vinyl alcohol) (PVA). We investigated the SiO2–PVA nanocomposite by Fourier transform infrared spectrometry (FT-IR) measurement, transmission electron microscopy and electron energy-loss spectroscopy, and the results revealed homogeneously dispersed SiO2 nanoparticles and PVA. We examined the relationship between the pH and ζ potential of the SiO2 suspension and the formability of the SiO2–PVA nanocomposite. Formability of the SiO2–PVA nanocomposite was dependent on the pH of the SiO2 suspension, and a monolithic SiO2–PVA nanocomposite without cracks was obtained using a SiO2 suspension at around the isoelectric point (pI). By sintering the SiO2–PVA nanocomposite in air at 1100°C, monolithic transparent silica glass was obtained with no cracks. The glass is highly transparent from the ultraviolet to the visible region.