Fig. 2: Real and simulated isotropic aerogel.

a Scanning electron microscopy of real, 98% porous isotropic aerogel shows the complex network of silica particles. b Simulated aerogel cluster for isotropic diffusion for a small segment of the sample (~0.5% of the total sample). Structural properties such as strand orientation, clustering, and void size are difficult to determine in the 3-D representation for the full sample. c Projecting the cluster onto orthogonal, 2-D planes reveals the position of silica spheres to be highly correlated. Each plane represents a projection of the aerogel sample along the axis perpendicular to that plane. For isotropic diffusion, the strands of silica appear to be without a preferred direction; however, characteristic clustering and void sizes are visibly apparent.