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REE- Lanthanides

Name

Terbium

Symbol

Tb

Atomic number

65

Group

HREE

Subgroup

terbium subgroup

Occurrence / Extraction

Terbium occurs with other Lanthanides in minerals such as monazite, cerite, gadolinite, xenotime, and euxenite.

Extraction:  converted to terbium fluoride (TbF3), then reacts with calcium metal to obtain free terbium.

Use


Terbium is primarily used in phosphors, particularly in fluorescent lamps and as the high intensity green emitter used in projection televisions, such as the yttrium-aluminum-garnet (Tb:YAG) variety. It is also used  in lasers, semiconductor devices and in solid-state devices, as stabilizer of fuel cells which operate at high temperature.

Terbium is used in the manufacture of fuel cells (chemical reactions to produce electricity). Terbium fuel cells operate effectively at very high temperatures.

Terbium responds efficiently to x-ray excitation and is, therefore, used as an x-ray phosphor. Terbium is often used in X-ray machines.

Terbium alloys are also used in magneto-optic recording films, such as TbFeCo.

Properties

Terbium is soft, ductile, silvery-grey, rare earth metal. Oxidizes slowly in air. Reacts with cold water.
 
Atomic mass:  158.925 g.mol -1
Electronegativity according to Pauling:  1.2
Density:  8.229 g.cm-3 at 20°C
Melting point: 1356 °C
Boiling point:  3041 °C.      
 
Named after Ytterby, a village in Sweden

Relative abundance

Terbium is one of the rarest of the Lanthanides. It ranks about 55th among the elements in the Earth's crust. It is about as abundant as molybdenum and tungsten, but more abundant than iodine, silver, and gold.

atomic mass (g.mol -1)

158.925

density (g/cm3)

8.2

Oxydation number

  +3

Melting point (°C)

1356

Boiling point (°C)

3041

Magnetic moment

 

Abundance in the Earth's crust ( ppm)

0.6

discovery

Carl Gustaf Mosander   in 1843