Michael Brooks
At Nasa’s research labs in the heart of Silicon Valley, alchemy is back in fashion. But turning base metals into gold is an old dream; the new alchemists are trying to turn coal into diamond. Re-arranging carbon atoms to build diamond-based materials would release a range of powerful new technologies – from silicon chips to space ships. The patent on the first diamond fibre will be almost priceless.
In South Africa, the University of the Witwatersrand has been involved in diamond research for 30 years, and has become an international focal point of diamond science technology, says Friedel Sellschop, Wits professor emeritus and an honorary professiorial research fellow at Schonland research centre. And in Europe, new research centres are springing up.
Nanotechnology, a field that deals in elements measured on the atomic scale in millionths of millimetres, is an integral part of diamond research. At the root of the nanotechnology dream is the idea of building structures from the bottom up.
The principle is simple: if you can rearrange the atoms in something, you can make something else. On a ham-fisted level, engineers are already rearranging the atoms in sand, adding some impurities and making silicon computer chips. The first people to rearrange single atoms of carbon, so that the bonds between graphite molecules are restructured to produce diamond molecules, will be instant millionaires.
In engineering terms, diamond is potentially the most useful material in existence. It is fantastically strong: carbon atoms form especially powerful bonds between themselves, and in diamond they are arranged to perfection, giving the stiffest structure possible.
Diamond is also very light: a 747 jumbo jet made of diamond fibres would be 50 times lighter than today’s, without any loss of strength. The advantages for space travel are that launch costs could be cut from 25 000 to around 200 a kg.
Diamond fibres are still a distant dream, but the next best thing has already arrived. Carbon nanotubes – rolled-up sheets of graphite less than a nanometre in dia-meter – are comparable to diamond in their strength along the tube’s length. Recent advances in the manufacture of nanotubes and buckyballs (their spherical counterpart) have woken a slumbering field.
It has already drawn the gaze of Nasa, IBM, and even the Pentagon. The White House has set up a division, led by Vice-President Al Gore, to look into the military potential of nanotechnology.
Nanotechnology aims to use biological systems as models of what can be built through the systematic manipulation of atoms and molecules. For example, the natural kinesin motor, which transports material inside cells, has been highlighted by Nasa as a possible basis for molecular gears. A carbon nanotube studded with benzene teeth could be used to make gears two nanometres across – six times smaller than the kinesin motor.
Ideas such as this are theoretically possible, and exist inside computer simulations. But diamond fibre production will require much more sophisticated techniques for controlling the behaviour of atoms than anything yet possible.
Currently, artificial diamond is principally grown by “chemical vapour deposition”. Under carefully controlled conditions of pressure and temperature, the diamond surface is bombarded with hydrogen and hydrocarbon molecules. Carbon molecules on the diamond’s surface have unused bonds, which can be made to react with the hydrocarbon molecules, gradually laying down more carbon layers.
But the process is too hit-and-miss for the fine control needed for building diamond fibres.
Achieving their goals will require huge investment, which seems to be forthcoming, although no one in the field expects nanotechnology research to pay any dividends until the middle of the next century.
“It’s still a dream,” says Sellschop.