Diaper rash preventive provides brilliant white lightDecember 19th, 2008 - 5:54 pm ICT by IANS
Washington, Dec 19 (IANS) A cheap and nontoxic sunburn and diaper rash preventive can be a source of brilliant white light best suited to the human eye.Duke University physics professor Henry Everitt, chemistry professor Jie Liu and their graduate student John Foreman have discovered that adding sulphur to ultra-fine powders of commonplace zinc oxide at about 1,000 degrees Celsius allows the preparation to convert invisible ultraviolet light into a remarkably bright and natural form of white light.
They are now probing the solid state chemistry and physics of various combinations of those ingredients to deduce an optimal design for a new kind of illumination.
Everitt and Liu have applied for a patent on using the preparations as a light source. “Our target would be to help make solid state lighting with better characteristics than current fluorescent ones,” said Everitt, who also works with Foreman at the Army’s Redstone Arsenal in Huntsville, Alabama.
The researchers said they are producing white light centred in the green part of the spectrum by forming the sulphur-doped preparation into a material called a phosphor. The phosphor converts the excited frequencies from an ultraviolet light emitting diode (LED) into glowing white light.
The researchers are also exploring using electricity alone to trigger the visible emissions without need for an ultraviolet light trigger, said a Duke University release.
“One of the objectives is to give soldiers efficient lighting that doesn’t run their batteries down,” Everitt said. “They need efficiency, brightness, longevity and ruggedness, and this helps with all of those things.”
Existing commercial LEDs are already rugged enough to be used in bumper-mounted brake lights, Everitt said.
“They are good enough for decoration and for use in traffic lights, but they don’t make good reading lights because they are not of a white colour that our eyes use best,” Liu said. White LEDs on the market now are costly, short-lived and not truly white, the researchers added.