September 1998

The Beach Yields a Bright Idea

By David Graham

Fluorescent lighting is the bane of many office workers' existence. But that isn't the only drawback of this form of illumination. The "phosphors" in a fluorescent light (the compounds that actually produce the visible radiation) typically contain such toxic metals as cadmium, silver, europium and lead. A California chemist has synthesized a surprising new compound made of the same elements found in beach sand (including a trace of driftwood) that might provide the basis for more environmentally benign phos-phors. And now a Tokyo-based company, C.I. Kasei, sees a bright commercial future for this intriguing new luminescent material.

Materials chemist Michael Sailor of the University of California, San Diego (UCSD), discovered last year that when he reacted carbon with a combination of silicon and oxygen (the elements in sand), the result was luminescent. "The carbon is behaving like metals do in the conventional phosphors, and that's the surprising part," says Sailor.

In recent work, Sailor has turned up the light-emitting properties of his compounds by adding a sprinkle of aluminum. Phosphors with the added aluminum provide illumination comparable to conventional fluorescents, Sailor told TR. He thinks the new compound also could be used in computer screen displays and wristwatches.

Some of these applications might be put to the test soon. C.I. Kasei has signed a deal with UCSD that allows the company to further develop the material.