Author: Jan Scholten
11.0 Terbium physical
Terbium is a silvery-gray rare earth metal that is malleable, ductile and soft enough to be cut with a knife. It is reasonably stable in air. Two crystal allotropes exist, with a transformation temperature of 1289°C.
Atomic Number: 65.
Discovery: 1843 by C.G. Mosander at Stockholm, Sweden.
Name: after Ytterby, a small village near Stockholm.
Toxicology: mildly toxic by ingestion, and is a skin and eye irritant.
Ore: cerite, gadolinite, xenotime (YPO4).
monazite ((Ce,LaTh,Nd,Y)PO4, with up to 0.03% of Terbium), euxenite ((Y,Ca,Er,La,Ce,U,Th) (Nb,Ta,Ti)2O6, with 1% or more of Terbium).
1. Lasers: NaTbBO3 laser at 5460A.
2. Color television: Tb2O3 gives the green color in TV and in green phosphors in fluorescent lamps.
3. Sonar: TbDyFe2, Terfenol, changes its volume in magnetic fields, used in sonar.
4. Magneto-optic discs: Tb(Gd)FeCo in magneto optic mini discs, as it loses its magnetism above 200 degrees.
5. Solid state devices: Sodium terbium borate is used to dope calcium fluoride, calcium tungstate and strontium molybdate, materials that are used in solid-state devices.
6. Fuel cells: crystal stabilizer of fuel cells which operate at elevated temperatures, together with ZrO2.