Yttrium

A soft, silver-white, highly reactive metal that spontaneously ignites in air when cut into pieces and is usually kept in nitrogen. Yttrium is incorporated into alloys of aluminum and magnesium to increase their strength, and is used in solid-state lasers, where Yttrium aluminum oxide (commonly known as YAG) enhances the energy of the light and is useful in metal drilling and cutting. The crystals formed by combining Yttrium oxide and iron oxide are used in the manufacture of microwave filters for radar technology, as well as in LED lighting and lasers. Yttrium oxide is added to glass to make bulletproof glass. Yttrium oxide can be used as a red light emitting phosphor in color television picture tubes.