Terbium is a chemical element, symbol Tb and atomic number 65. It is a
silver gray metal from the lanthanide family belonging to the group of rare
earths.
The name terbium, comes from the place, Ytterby near Stockholm in Sweden, where
the ore was discovered in which several other rare earths have also been
identified. The chemical elements yttrium, erbium and ytterbium share the same
etymology.
Today terbium is extracted from monazite sand (content of about 0.03%) like many
other lanthanides.
Terbium is a non-renewable resource. A publication by the French National Center
for Scientific Research even predicted its exhaustion for 2012
Terbium is a silver gray metal. Like other members of the lanthanide family, it
is malleable, ductile, and soft enough to be cut with a knife. It is fairly
stable in air, and exists in two allotropic forms, with a phase change at 1,289
¡ã C21.
Terbium crystal structure.
Like all heavy rare earths, terbium has a crystal structure in a hexagonal
compact stack. Below its Curie point (−54.15 ¡ã C), it shows a simple
ferromagnetic arrangement with the moments aligned along the axis b of the basal
plane. Above Tc, the element does not immediately become paramagnetic, but
rather reaches a particular antiferromagnetic state which persists until its
Neel temperature (−43.15 ¡ã C). This arrangement, known as helical
antiferromagnetism, is characterized in that all the magnetic moments of the
same layer are parallel and oriented at a fixed angle relative to the moments of
the adjacent layers. They thus rotate around the c axis like a screw or a
propeller. Dysprosium shares these special characteristics for other
temperatures22. These two elements also have a high magnetostriction10.
The terbium (III) cation exhibits an important green fluorescence. It involves a
5D4 ¡ú 7F5 transition whose main emission band is located at 545 nm, with a life
time of 0.1 to 2 ms
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rhenium germanium zirconium cadmium hafnium
barium lithium beryllium strontium calcium
Tantalum gadolinium samarium yttrium ytterbium
Lutetium praseodymium holmium erbium thulium dysprosium
terbium europium lanthanum cerium neodymium scandium
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