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Beginning in 1908, luminous paint containing a mixture of radium and copper-doped zinc sulfide was used to paint watch faces and instrument dials, giving a greenish glow. Phosphors containing copper-doped zinc sulfide (ZnS:Cu) yield blue-green light; copper and manganese-doped zinc sulfide (ZnS:Cu,Mn), yielding yellow-orange light are also used ...
Although old radium dials generally no longer produce light, this is due to the breakdown of the crystal structure of the luminous zinc sulfide rather than the radioactive decay of the radium. The radium isotope ( 226 Ra ) used has a half-life of about 1,600 years, [ 7 ] so radium dials remain essentially just as radioactive as when originally ...
Radium paint used zinc sulfide phosphor, usually trace metal doped with an activator, such as copper (for green light), silver (blue-green), and more rarely copper-magnesium (for yellow-orange light). The phosphor degrades relatively fast and the dials lose luminosity in several years to a few decades; clocks and other devices available from ...
The company's luminescent paint, marketed as Undark, was a mixture of radium and zinc sulfide; the radiation causing the sulfide to fluoresce. During World War I, demand for dials, watches, and aircraft instruments painted with Undark surged, and the company expanded operations considerably.
Thin-film zinc sulfide doped with manganese (producing orange-red color) Naturally blue diamond , which includes a trace of boron that acts as a dopant. Semiconductors containing Group III and Group V elements, such as indium phosphide (InP) , gallium arsenide (GaAs) , and gallium nitride (GaN) ( Light-emitting diodes ).
Between 1913 and 1950 radium-228 and radium-226 were used to activate a phosphor made of silver doped zinc sulfide (ZnS:Ag), which gave a greenish glow. The phosphor is not suitable to be used in layers thicker than 25 mg/cm 2 , as the self-absorption of the light then becomes a problem.
The resulting dials are now collectively known as radium dials. The luminous paint used on the dials contained a mixture of zinc sulfide activated with silver, and powdered radium, a product that the Radium Dial Company named Luma. However, unlike the US Radium Corporation, Radium Dial Company was specifically set up to only paint dials, and no ...
Like other gas-discharge lamps such as the very-similar mercury-vapor lamps, metal-halide lamps produce light by ionizing a mixture of gases in an electric arc.In a metal-halide lamp, the compact arc tube contains a mixture of argon or xenon, mercury, and a variety of metal halides, such as sodium iodide and scandium iodide. [7]