Small transparent aerogel

Sol-gel processing is an attractive route for the production of porous ceramics and glasses because the characteristic properties of gels such as high surface area, high porosity, and small pore size are not easily attainable by more conventional methods. In addition to the transparent aerogel applications mentioned above, these unique properties are exploited in a variety of applications, which include filtration, separation, catalysis, and chromatography (1,61,71). 

Figure 45.11 Two images of small transparent (although blurred) aerogel samples [92].

All applications of aerogels make use of their high porosity, which is responsible for the low index of refraction, the small Young s modulus, the low acoustic impedance, the low thermal conductivity, and the excellent accessibility of the inner surface. In addition, in some applications the high optical transparency is of importance. 

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