Silica Aerogel: Synthesis and Applications

Table 2

Typical properties of silica aerogels.

Property	Value
Apparent density	0.03–0.35 g/cm^3
Internal surface area	600–1000 m^2/g
% solids	0.13–15%
Mean pore diameter	~20 nm
Primary particle diameter	2–5 nm
Refractive index	1.0–1.08
Coefficient of thermal expansion	2.0-4.0×10^−6
Dielectric constant	~1.1
Sound velocity	100 m/s