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Gadolinium is a rare earth metal. It is silver gray,
malleable and ductile at room temperature.
It crystallizes in hexagonal form at room temperature, but has another
allotropic form known as the beta form, with a cubic structure centered above 1
508 K.
Gadolinium is fairly stable in dry air. However, it oxidizes quickly in humid
air. Gadolinium reacts slowly with water and is soluble in dilute acids.
Gadolinium oxide was isolated in 1880 by Jean Charles Galissard de Marignac, and
Paul-Émile Lecoq de Boisbaudran prepared pure metal in 1886. It is named in
honor of the Finnish chemist Johan Gadolin7, a.
Gadolinium is classically considered to be one of the four ferromagnetic
elementsb but its TC Curie point is very low (around 292 K, or 19 กใ C). The real
nature of this magnetism ordered below TC is disputed8.
Gadolinium has the greatest absorption capacity for thermal neutrons among all
natural elements (49 kilobarns1).
Gadolinium has some toxicity. In fact, it competes with calcium in the
calcium-dependent processes of the human body (breathing, heartbeat, muscle
contraction, coagulation ...) and can lead to serious damage depending on its
concentration. This is why the gadolinium compounds which are used in medicine
as a contrast agent for magnetic resonance imaging (MRI) are necessarily
complexed.
Gadolinium is characterized by a particularly low mineralogical diversity: only
one mineral is known of which it is an essential constituent, lepersonnite- (Gd).
It is rather found in solid solution in various minerals rich in rare earths.
Today it is mainly extracted from monazite (Ce, La, Th, Nd, Y) PO4 and
bastnäsite (en) (Ce, La, Y) CO3F.
use
Alloys: Gadolinium (up to 1%) is added to chromium steel to improve hardness and
processing properties.
Gd3Ga5O12 gadolinium-gallium garnet (GGG) is used to make lasers, once doped
with neodymium, ytterbium or dysprosium. Developments are underway to develop
X-ray lasers with Nd: GGG. GGG is also used as a substrate for the fabrication
of thin film microwave components (ferrites).
Phosphorescent substance in cathode ray tubes.
Superconductive alloys.
Contrast agent in magnetic resonance imaging (MRI) where it is associated with a
chelator or a ligand. This product tends to accumulate in the brain without its
toxicity being fully known9. Certain gadolinium chelates (macrocyclic agents) do
not cause a neurological deficit10. In addition, this heavy metal is toxic (even
fatal) for people with kidney disease and can cause an inflammatory reaction11.
Neutron absorbent:
in its oxidized form Gd2O3 in certain nuclear reactors in order to limit
reactivity at the start of life thanks to the neutron absorbing properties of
the isotopes 155Gd (61 kilobarns1) and especially 157Gd (254 kilobarns1) which
by capture are transformed into the isotope 156Gd and 158Gd, practically
non-absorbent (cross sections of the order of the barn). The kinetics of wear of
Gadolinium is very specific (skin effect) indeed under irradiation its neutron
weight remains fairly constant until a breaking point where its effectiveness
decreases very quickly.
In 2019, gadolinium was added to the water of the Japanese super-Kamiokande
neutrino observatory in order to be able to detect the neutrons produced by
collisions between antineutrinos emitted by supernovas and protons present in
water molecules12.
French team tests refrigerator that works by magnetizing this material
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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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