Editing Terbium (section)

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'''Terbium''' is a [[chemical element]]; it has [[Symbol (chemistry)|symbol]] '''Tb''' and [[atomic number]] 65. It is a silvery-white, [[rare earth element|rare earth]] [[metal]] that is [[malleable]] and [[ductile]]. The ninth member of the [[lanthanide]] series, terbium is a fairly [[electropositive]] metal that reacts with water, evolving [[hydrogen]] gas. Terbium is never found in nature as a free element, but it is contained in many [[mineral]]s, including [[cerite]], [[gadolinite]], [[monazite]], [[xenotime]] and [[euxenite]].

Swedish chemist [[Carl Gustaf Mosander]] discovered terbium as a chemical element in 1843. He detected it as an impurity in [[Yttrium(III) oxide|yttrium oxide]] ({{chem2|Y2O3}}). [[Yttrium]] and terbium, as well as [[erbium]] and [[ytterbium]], are named after the village of [[Ytterby]] in Sweden. Terbium was not isolated in pure form until the advent of [[ion exchange]] techniques.

Terbium is used to [[dopant|dope]] [[calcium fluoride]], calcium [[tungstate]] and [[strontium]] [[molybdate]] in [[solid-state device]]s, and as a crystal stabilizer of [[fuel cell]]s that operate at elevated temperatures. As a component of [[Terfenol-D]] (an alloy that expands and contracts when exposed to magnetic fields more than any other alloy), terbium is of use in [[actuator]]s, in naval [[sonar]] systems and in [[sensor]]s. Terbium is considered non-hazardous, though its biological role and toxicity have not been researched in depth.

Most of the world's terbium supply is used in green [[phosphor]]s. Terbium [[oxide]] is used in [[fluorescent lamp]]s and television and monitor [[cathode-ray tube]]s (CRTs). Terbium green phosphors are combined with divalent [[europium]] blue phosphors and trivalent europium red phosphors to provide [[trichromatic]] lighting technology, a high-efficiency white light used in indoor lighting.