Aerogel is a synthetic porous ultralight material derived from a gel, in which the liquid component of the gel has been replaced with a gas. The result is a solid with extremely low density and thermal conductivity. Aerogels can be made from a variety of materials, including silica, carbon, and metal oxides. They are typically produced by a sol-gel process, in which a precursor solution is first formed and then undergoes a gelation process to form a wet gel. The wet gel is then dried to remove the liquid component, leaving behind the aerogel.
Aerogels have a number of unique properties that make them useful for a variety of applications. They are extremely lightweight, with densities as low as 0.003 g/cm, and have very low thermal conductivity, making them excellent thermal insulators. Aerogels are also highly porous, with porosities as high as 99.9%, and have a high surface area, making them ideal for applications such as catalysis and filtration. In addition, aerogels are transparent to visible light and can be made in a variety of colors, making them useful for applications such as optics and displays.