Gadolinium
For computer memory.
Atomic Number: 64
Atomic Symbol: Gd
Atomic Weight: 157.25
Electron Configuration:[Xe]6s^2 4f^7 5d^1History
From gadolinite, a mineral named for Gadolin, a Finnish chemist. The rare earth metal is obtained from
the mineral gadolinite. Gadolinia, the oxide of gadolinium, was separated by Marignac in 1880 and
Lecoq de Boisbaudran independently isolated it from Mosander's yttria in 1886.
Sources
Gadolinium is found in several other minerals, including monazite and bastnasite, both of which are
commercially important. With the development of ion-exchange and solvent extraction techniques, the
availability and prices of gadolinium and the other rare-earth metals have greatly improved. The metal
can be prepared by the reduction of the anhydrous fluoride with metallic calcium.
Isotopes
Natural gadolinium is a mixture of seven isotopes, but 17 isotopes of gadolinium are now recognized.
Although two of these, 155Gd and 157Gd, have excellent capture characteristics, they are only present
naturally in low concentrations. As a result, gadolinium has a very fast burnout rate and has limited use
as a nuclear control rod material.
Properties
As with other related rare-earth metals, gadolinium is silvery white, has a metallic luster, and is
malleable and ductile. At room temperature, gadolinium crystallizes in the hexagonal, close-packed alpha
form. Upon heating to 1235oC, alpha gadolinium transforms into the beta form, which has a
body-centered cubic structure.
The metal is relatively stable in dry air, but tarnishes in moist air and forms a losely adhering oxide film
which spalls off and exposes more surface to oxidation. The metal reacts slowly with water and is soluble
Gadolinium