Microporous silica thin films with low refractive indices and high Young's modulus

A microporous silica thin film with low refractive index (low-n) of 1.27 and high Young's modulus of 19.5 GPa was obtained by sol-gel synthesis using hydroxyacetone catalyst with tetramethyl orthosilicate and water in ethanol. Transmission electron microscope images and nitrogen adsorption-desorption measurements showed that the pores in the synthesized silica were <1 nm in diameter. Unlike many other microporous synthesis methods, our method did not require sacrificial reagents as templates. This allowed low-temperature fabrication of high-strength low-n silica.