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For fluorescent lamps.

Atomic Number:65Atomic Symbol:Tb
Atomic Weight:158.9254Electron Configuration:2-8-26-9-2
Shells:2,8,18,27,8,2Filling Orbital:4f9
Melting Point:1360oCBoiling Point:3041oC
Description:Silvery rare earth metal.


(Ytterby, a villiage in Sweden) Discovered by Mosander in 1843. Terbium is a member of the lanthanide or "rare earth" group of elements.


  • It is found in cerite, gadolinite, and other minerals along with other rare earths.
  • It is recovered commercially from monazite in which it is present to the extent of 0.03%, from xenotime, and from euxenite, a complex oxide containing 1% or more of terbia.
  • Terbium has been isolated only in recent years with the development of ion-exchange techniques for separating the rare-earth elements.
  • As with other rare earths, it can be produced by reducing the anhydrous chloride or fluoride with calcium metal in a tantalum crucible.
  • Calcium and tantalum impurities can be removed by vacuum remelting.
  • Other methods of isolation are possible.


  • Terbium is reasonably stable in air.
  • It is a silver-gray metal, and is malleable, ductile, and soft enough to be cut with a knife.
  • Two crystal modifications exist, with a transformation temperature of 1289C.
  • Twenty one isotopes with atomic masses ranging from 145 to 165 are recognized.
  • The oxide is a chocolate or dark maroon color.


  • Sodium terbium borate is used in solid-state devices.
  • The oxide has potential application as an activator for green phosphors used in color TV tubes.
  • It can be used with ZrO2 as a crystal stabilizer of fuel cells which operate at elevated temperature.
  • Few other uses have been found.


The element is priced at about $30/g (99.9%).

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