Description
تفصیل
is a chemical element with the symbol Tb and atomic number 65. It is a silvery-white rare earth metal that is malleable, ductile and soft enough to be cut with a knife. Terbium is never found in nature as a free element, but it is contained in many minerals, including cerite, gadolinite, monazite, xenotime and euxenite.
Terbium is used to dope calcium fluoride, calcium tungstate and strontium molybdate, materials that are used in solid-state devices, and as a crystal stabilizer of fuel cells which operate at elevated temperatures.
The largest consumer of the world's terbium supply is in "green" phosphors (which are usually yellow). Terbium oxide is in fluorescent lamps and TV tubes. Terbium "green" phosphors
2 Tb + 6 H2O →
Tb(OH)3 + 3 H2
Terbium was discovered in 1843 by Swedish chemist Carl Gustaf Mosander, who detected it as an impurity in Yttrium oxide, Y2O3, and named after the village Ytterby in Sweden. It was not isolated in pure form until the recent advent of ion exchange techniques.
Terbium is never found in nature by itself, but is contained along with other rare earth elements in many minerals, including monazite
References
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^ M. Jackson (2000). "Magnetism of Rare Earth". The IRM quarterly 10 (3): 1.
^ D.M. Gruen, W.C. Koehler, and J.J. Katz (April 1951). "Higher Oxides of the Lanthanide Elements: Terbium Dioxide" (PDF). Journal of the American Chemical Society: 1475.
^ a b c d e Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. pp. 920–921. ISBN 0070494398. Retrieved 2009-06-06.
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