Silica AeroGels

The Microstructured Materials Group at Berkeley Lab was formed in 1981 by Dr. Arlon Hunt. The initial focus of the group involved the study of small particles as an energy absorbing medium for solar-thermal systems. These studies included fundamental methods of producing small carbon particles and their optical and thermal properties under concentrated solar radiation. Shortly thereafter, the reappearance of aerogels in research circles presented an obvious opportunity to extend the ongoing solar energy program to a new class of materials. For several years, the group studied the fundamental chemistry and physics of the preparation of silica aerogels. A major advance came in 1983, with the development of the CO₂ substitution/drying process. This greatly reduced the hazards and costs associated with the production of aerogels. In 1988 light scattering methods used to study aerogels were extended to the study of sea water and ocean optics in general. This eventually evolved into scattering studies of sea ice and biological organisms (dinoflagellates and sickle cells, etc). Aerogel work has continued, with recent developments including new methods for forming composite aerogels via chemical vapor infiltration, processes leading to photoluminecsent silica aerogels, theoretical and experimental studies of the thermal conductivity of aerogels, investigation into the effects of microgravity of gel formation, and silica aerogels as kinetic-energy absorbing materials. Major facilities and equipment developed and operated by the group include: a solar simulator capable of producing a light intensity of up to 16,000 suns, a polarization nephelometer for light scattering studies, a bistatic polarization nephelometer for remote measurements and field work, a thin-film-heater device for measuring thermal conductivity of vacuum insulation panels, and a semi-automated supercritical drying system with a 40-liter capacity.