Uses of Rare Earths

The rare-earth metals have their greatest use in the glass, ceramic, electronics, and petroleum industries. Various compounds or mixtures of the rare earths are used as abrasives in polishing lenses, mirrors, and other glass products. Other compounds are used in coloring or decoloring glass, making glass impervious to ultraviolet light, and improving the quality of optical glass. Certain rare-earth oxides have long been used in making ceramic glass. Still other compounds are important in the manufacture of certain solid-state devices and used in the red phosphors on the screen of color television tubes. Mixtures of rare-earth chlorides are used as catalysts in petroleum refining.

Misch metal is composed of a mixture of a number of rare earths. An alloy of misch metal and iron ignites when scratched and is used as a flint in cigarette lighters. The alloy is also used in gas lighters, in miners' safety lamps, and in tracer bullets. Misch metal is also used to increase the heat resistance of aluminum and magnesium, and to improve the rolling properties of steel. Oxides and fluorides of the rare earths are used to make the cores of carbon-arc electrodes, which produce a brilliant white light and are used in motion-picture lighting equipment.