The mineral gadolinite was discovered in a quarry near the town of Ytterby, Sweden in 1784, and has been the source of a great number of newly described rare earth elements. In 1843, Carl Gustaf Mosander, a Swedish chemist, was able to separate gadolinite into three compounds; one of which eventually was named terbium after the city where it was found.
Terbium is a silvery-white rare earth metal that is malleable, ductile and soft enough to be cut with a knife. It is reasonably stable in air and very slow to oxidize or tarnish.
Terbium occurs in a number of minerals, usually in association with other heavy rare earth elements. It is mainly produced by solvent extraction of rare earth elements from clay deposits in China.
APPLICATIONS OF TERBIUM
Energy and Electronics: Terbium oxide (Tb2O3 or ´terbia´) is used in green phosphors in fluorescent lamps and colour TV tubes. When the terbium ´green´ phosphors, which actually fluoresce a brilliant lemon-yellow, are combined with divalent europium blue phosphors and trivalent europium red phosphors, they provide ´trichromatic´ or 3 wavelength fluorescent lighting. Trichromatic fluorescent lighting is a harsh white light with a much higher light output for a given amount of electrical energy than conventional fluorescent lighting and this application is by far the largest consumer of the world's terbium supply.
Terbium, along with zirconium dioxide (ZrO2), is also a crystal stabilizer in fuel cells that operate at high temperatures. Sodium terbium borate is used to make special lasers. Terbium is also used to dope calcium fluoride, calcium tungstate, sodium borate and strontium molybdate materials that are used in solid-state devices.
Science and Materials: Terbium is a component of Terfenol-D (Terbium Dysprosium and Iron), an alloy that expands or contracts to a high degree in the presence of a magnetic field. This material is used in actuators, sensors and other magenetomechanical devices.
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