Higher refractive index and lower wavelength dispersion of SiO2 glass by structural ordering evolution via densification at a higher temperature

Abstract

Large-sized densified silica glasses were fabricated at a high pressure of 7.7 GPa and high temperatures. As the synthesis temperature was increased from room temperature to 1200 °C, the densification increased to 23%. The wavelength dispersion of the refractive index in the visible region showed that not only the refractive index but also the Abbe number rose as high as those of crystalline silica as the synthesis temperature increased. The reflectance spectra in the vacuum ultraviolet region revealed that glasses densified at a higher temperature underwent homogeneous evolution of their structural ordering in an intermediate range. It was suggested that the decrease in randomness of the glass structure resulted in the increase in the refractive index and the Abbe number. The densification of glass at higher temperatures, which controls competing properties such as the refractive index and the Abbe number in the same direction, is a promising way to extract the latent potential of materials.