by Kathy Chambers 05 Jan, 2015 in
Sometimes the ordinary things we use every day can lead to extraordinary discoveries. This was truly the case when physicists Andre Geim and Konstantin Novoselov used the humble adhesive tape to extract single layers of graphene from graphite.
Although graphene had been theorized years before, it was thought to be impossible to isolate such thin crystalline materials in a laboratory. Geim and Novoselov not only exfoliated their thin sheets of graphene, they transferred them to a silicon substrate, the standard working material in the semiconductor industry and did electrical characterization on the graphite layers. Their discovery was published in 2004 and in 2010 they were awarded the Nobel Prize in Physics for successfully producing, isolating, identifying and characterizing graphene. Their adhesive tape, dispenser, chuck of graphite and a graphene transistor (shown above) were donated to the Nobel Museum in Stockholm.
Graphene is a single layer of carbon packed in a hexagonal (honeycomb) lattice and the first in a new class of two-dimensional crystalline materials with remarkable mechanical and electrical properties. Graphene is the strongest known substance, 200 times stronger than steel, so dense that the smallest gas atom helium cannot pass through it. It is an unmatched thermal and electrical conductor, stable, stretchable, transparent and impermeable.
Graphene holds much promise. Since the 2003 discovery, graphene research has increased substantially in many areas, including the development of solar cells, composite materials, lithium-ion batteries, biological and chemical sensors, transistors, inkjet printing of next generation electronics, telecommunications, novel coatings and lubricants. Department of Energy...Read more...
Aerogels are some of the most fascinating materials on the planet. They were discovered in the 1930s by Stanford University’s Samuel Kistler who proved that he could successfully replace a gel’s liquid with a gas by drying it, thereby creating a substance that was structurally a gel, but without liquid. Since their invention aerogels have primarily been made of silica but can be made of a growing variety of substances including transition metal oxides, organic polymers, biological polymers, semiconductor nanostructures, graphene, carbon, carbon nanotubes and metals as well as aerogel composite materials and the list is growing.
A brief glimpse of beautiful aerogels shows us they are in a class by themselves with combinations of materials properties that no other material possesses. And, these properties can be adjusted by tailoring the production process. Among other characteristics, aerogels are solid, rigid, and dry despite being named gels. They are the lightest known solids in existence and made of almost nothing. Silica aerogels, for example, typically consist of more than 96% air and the remaining 4% is a wispy web of silica. Their looks are also deceiving. You might think you could pass your hand right through a transparent silica aerogel, sometimes nicknamed ‘frozen smoke,’ but think again—it is very solid to the touch. Extraordinarily strong, aerogels are able to support over 2000 times their own weight. They are also very fragile-- at first cushiony to the touch, they shatter with a bit more pressure. They are good thermal insulators and are capable of withstanding temperatures in excess of 1000 degrees Fahrenheit. They can be mixed, formed, spread, sprayed or fabricated into slabs, pellets, or most any shape desirable. Because aerogels have these incredible characteristics, they are outstanding materials for...Read more...