Ordering analysis of SiO₂ particle-accumulated films by small-angle X-ray scattering

Abstract

The ordered arrangement of particles and holes in SiO₂ particle-accumulated films by small-angle X-ray scattering (SAXS) was investigated. The SAXS profiles of SiO₂ particles exhibited the typical oscillation shown by monodisperse spherical particles. On the other hand, the SAXS profile of the ordered SiO₂ particle-accumulated film showed an additional oscillation suggesting that another scattering component existed except for SiO₂ particles. Furthermore, considering two components: “SiO₂ in an air matrix” and “air holes in a SiO₂ matrix”, we successfully reproduced the SAXS profile of the ordered particle-accumulated film. The additional oscillation shows the existence of the tetrahedral holes, suggesting that this SiO₂ particle-accumulated film forms a close-packed structure. The intensity of the additional oscillation increased with the regularity of the particle arrangement in the SiO₂ particle-accumulating film. These results suggest that SAXS measurements using synchrotron radiation can provide information on the order of particle arrangement in composite films.