New phosphor for fluorescent bulbs.

Although fluorescent light bulbs are bright and energy-efficient, they use toxic mercury vapors and expensive phosphors in producing their characteristic glow. Now, chemists at the University of California, San Diego in La Jolla have found a more environmentally friendly alternative: silicate contaminated with carbon. The material, which shines bright white when excited with low-energy ultraviolet light, could potentially replace the phosphors found in existing bulbs.

To synthesize the material, Michael J. Sailor and his colleagues formed a network of porous silicate, using a sol-gel technique. The building blocks of the network, tetraalkoxysilanes, react together in a solution of carboxylic acid. When the liquid is removed, the rigid network remains (SN: 1/25/97, p.56). Ultraviolet energy excites the carbon atoms in the silicate to produce the visible, white light, Sailor says. The study appears in the June 20 Science.

Different kinds of silicates and acids produced variations on the material. Some were water-soluble, took the form of colored glasses, or could be drawn into long fibers or cast into thick films. The material needs less energy to glow than existing fluorescent bulbs, making it attractive for battery-powered devices such as the displays on laptop computers.