Yttrium

Yttrium, chemical element, symbol Y; for physical constants, see Periodic Table. Yttria, an earth (oxide) containing yttrium, was discovered in 1794 by John Gadolin. Yttrium was first isolated by Friedrich Wohler in 1828. Yttrium occurs in nature as xenotime (yttrium phosphate), and other minerals, monazite being the commercial source. It is obtained by the reduction of the fluoride with calcium metal. Yttrium is a silvery-white, soft, reactive metal. Although not a member of the rare-earth series of metals, it is chemically similar and often considered with them. Yttrium and its compounds are used in phosphors for color televisions, in yttrium aluminum garnets used in YAG-lasers, and in mantles for incandescent lamps. In 1843 Carl Gustav Mosander divided the earth yttria into three earths, which then were named yttria, erbia, and terbia.