Miracle material

At a time, when research in science has turned out to be very expensive and complex, it is unbelievable that a simple adhesive tape can bring in a major breakthrough in physics and begin a new era in the world of materials. This new material is graphene.

Andre Geim and Konstantin Novoselov from the University of Manchester in the UK received Nobel Prize in 2010 for their effort of stabilising two-dimensional crystalline carbon known as graphene. By delicately cleaving graphite tape, Andre’s group produced this novel material with unique properties. Graphene may be one of the most promising and versatile materials ever discovered. It could hold the key to everything from tiny computers to high-capacity batteries. 

“Graphene is absolutely thin material, one million times thinner than paper. It also has the largest surface-to-weight ratio: with one gram of graphene you can cover several football pitches. It is thousand times stronger than today’s best quality steel. Graphene is as good an electrical conductor at room temperature as copper. It also outperforms all other known materials as a heat conductor. Above all, it is both very dense and almost completely transparent,” is how Andre and Konstantin describe properties of graphene.

New form of carbon

What is graphene? It’s a new form of carbon and is the most fascinating element in the periodic table. It can exist in several different forms. The most common form of carbon is graphite and consists of stacked sheets of carbon with a hexagonal (honeycomb) structure. The single layer of carbon is what we call graphene. Graphene-like structures were known to scientists since the 1960s. However isolation of stable sheets of graphene was not thought possible.

It, therefore, came as a surprise to the physics community when in 2004, Andre’s group showed that such a single layer could be isolated and that it was stable. Graphene is believed to be two-dimensional as it is supposed to have only length and breadth – without any thickness. Many physicists believed that a 2-D crystal like graphene would always roll up rather than stand free in a planar form; but Andre’s group was able to stabilise graphene in a planar form.

They were able to visualise graphene not with any extraordinary microscope but using a simple optical microscope. When we write on a piece of paper with a pencil, the graphite is cleaved into thin layers that end up on the paper. A small fraction of these thin layers of graphite on the paper will contain only a few layers or even a single layer of graphite, i.e. graphene. Andre and Konstantin first produced graphene in 2004 by repeatedly peeling away graphite strips with adhesive tape to isolate a single atomic plane.
 
Later in 2008, the team created a one-nanometer graphene transistor (basic building block of any electronic circuit). This transistor was only one atom thick and 10 atoms across. This is not only smaller than the smallest possible silicon transistor; Konstantin claimed that it could very well represent the absolute physical limit of Moore’s Law governing the shrinking size and growing speed of computer processors.

Graphene is a goldmine

The true potential of graphene lies in its ability to carry electricity and light both simultaneously. The electrons in graphene can travel large distances without being scattered, making it a promising material for very fast electronic components. Strong, flexible, light-sensitive graphene can improve the efficiency of solar cells and LEDs.

It can also help in the production of next-generation devices like flexible touch screens, photodetectors and ultrafast lasers. In particular, graphene can replace rare and expensive metals like platinum and indium, performing the same tasks with greater efficiency at a fraction of the cost. New types of composite materials based on graphene with great strength and low weight could also become interesting for use in satellites and aircraft.

Recently the graphene duo showed ways of using graphene to convert light into electric pulses at high speeds, a development that could result in better solar cells and 10-100 times faster Internet.

Fresh developments

Rice University team has created a new type of graphene-based, flash-like storage memory, denser than any existing storage technology. This super dense data storage system will seek huge applications in computer memories. The energy applications of graphene are also extraordinarily. Many companies currently trying to create wearable electronics — clothes that can power and charge electrical devices — are using graphene as it is extremely thin and potentially less expensive to produce. 

A group of scientists at the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) at Bangalore has shown that graphene is useful for storing carbon dioxide and hydrogen. “Graphene is a useful material for carbon dioxide separation and storage,” says senior scientist CNR Rao. 

Over 200 patents have been granted on graphene since its discovery. This shows the extent of commercial interest in the material. According to Andre, graphene is not only commercially important but it can also used to make bench-top experiments to study the subtle physics of quantum electrodynamics, a branch of physics that deals with subatomic particles. “Graphene makes possible experiments with high-speed quantum particles that researchers at CERN can only dream of,” says Andre. Undoubtedly this material is going to rule 21st century!

(The writer is Associate Professor, Birla College, Mumbai.)