The existence of gadolinium was first noted by the Swiss chemist Marignac in 1880 in the mineral samarskite. The element was eventually named after Gadolin, a Finnish chemist, whose name was also given to another rare earth mineral, gadolinite.
Today, gadolinium is primarily obtained from the Chinese ion adsorption clays and less so from the minerals xenotime (Y, REE PO4), monazite ((Ce,La,Th,Nd,Y)PO4) and bastnaesite ((Ce,La,Y)CO3F).
Gadolinium is a silvery-white, malleable and ductile metal with a metallic lustre. Unlike other rare earth elements, gadolinium metal is relatively stable in dry air. It does however tarnish quickly in moist air, forming a loosely-adhering oxide which flakes off, and exposes the underlying surface to further oxidation. It reacts slowly with water, and is soluble in dilute acids.
Gadolinium is weakly magnetic, or paramagnetic, at room temperature, but becomes strongly magnetic or ferromagnetic below room temperatures.
Gadolinium, particularly in alloy form e.g. Gd5(Si2Ge2), demonstrates a magnetocaloric effect whereby its temperature increases when it enters a magnetic field and decreases when it leaves the magnetic field.
APPLICATIONS OF GADOLINIUM
Materials and Electronics: Gadolinium is used in making gadolinium yttrium garnets, which have microwave applications, and gadolinium compounds are used for making phosphors for colour TV tubes. Gadolinium is also used for manufacturing compact discs and computer memory.
It also possesses unusual metallurgic properties, in which, as little as 1% of gadolinium improves both the workability of iron, chromium, and related alloys and raises their resistances to high temperature oxidation.
Future applications may include its use as a magnetic component for sensing hot and cold, by levering its high magnetic moment and low Curie temperature.
Medical: Solutions of organic gadolinium complexes and gadolinium compounds are used as intravenously administered, contrasting agents to enhance images in medical magnetic resonance imaging (MRI). Gadolinium is also used in X-ray imaging where terbium-doped, gadolinium oxysulfide as a phosphor converts the X-rays released from a source into light. Cerium-doped gadolinium oxyorthosilicate is a single crystal used as a scintillator in medical imaging such as Positron Emission Tomography (PET).
Because it has a high neutron capture cross-section, gadolinium is very effective for use with neutron radiography.
Specialty Glass: Gadolinium gallium garnet (Gd3Ga5O12) is used in fabrication of various optical components and as substrate material for magneto-optical films.
Energy: Gadolinium is used in nuclear marine propulsion systems as a burnable nuclear poison and as a secondary, emergency shut-down measure in some nuclear, particularly CANDU type, reactors.