Gadolinium was discovered in 1880 by Jean Charles de Marignac, who detected its oxide by using spectroscopy.

Because of its paramagnetic properties, solutions of chelated organic gadolinium complexes are used as intravenously administered gadolinium-based MRI contrast agents in medical magnetic resonance imaging.

In fact, at body temperature, gadolinium exhibits the greatest paramagnetic effect of any element.

[15] Individual gadolinium atoms can be isolated by encapsulating them into fullerene molecules, where they can be visualized with a transmission electron microscope.

It also combines with nitrogen, carbon, sulfur, phosphorus, boron, selenium, silicon, and arsenic at elevated temperatures, forming binary compounds.

[18] Unlike the other rare-earth elements, metallic gadolinium is relatively stable in dry air.

Gadolinium(III), like most lanthanide ions, forms complexes with high coordination numbers.

The predicted double beta decay of 160Gd has never been observed (an experimental lower limit on its half-life of more than 1.3×1021 years has been measured[21]).

The French chemist Paul-Émile Lecoq de Boisbaudran carried out the separation of gadolinium metal from gadolinia in 1886.

[10] The main mining areas are in China, the US, Brazil, Sri Lanka, India, and Australia with reserves expected to exceed one million tonnes.

Gadolinium metal is obtained from its oxide or salts by heating it with calcium at 1,450 °C (2,640 °F) in an argon atmosphere.

The use of gadolinium in neutron capture therapy to target tumors has been investigated, and gadolinium-containing compounds have proven promising.

[35] Traditional gadolinium-based contrast agents are un-targeted, generally distributing throughout the body after injection, but will not readily cross the intact blood–brain barrier.

Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) at the phosphor layer converts the X-rays released from the source into light.

[citation needed] Gadolinium oxyorthosilicate (Gd2SiO5, GSO; usually doped by 0.1–1.0% of Ce) is a single crystal that is used as a scintillator in medical imaging such as positron emission tomography, and for detecting neutrons.

[39] It is also used as a gamma-ray source in X-ray absorption measurements and in bone density gauges for osteoporosis screening.

Using gadolinium as a dopant for materials like cerium oxide (in the form of gadolinium-doped ceria) gives an electrolyte having both high ionic conductivity and low operating temperatures.

[15] Gadolinium barium copper oxide (GdBCO) is a superconductor[41][42][43] with applications in superconducting motors or generators such as in wind turbines.

[44] It can be manufactured in the same way as the most widely researched cuprate high temperature superconductor, yttrium barium copper oxide (YBCO) and uses an analogous chemical composition (GdBa2Cu3O7−δ ).

[48] Gadolinium is used for antineutrino detection in the Japanese Super-Kamiokande detector in order to sense supernova explosions.

[49] Gadolinium gallium garnet (GGG, Gd3Ga5O12) was used for imitation diamonds and for computer bubble memory.

[50] As a free ion, gadolinium is reported often to be highly toxic, but MRI contrast agents are chelated compounds and are considered safe enough to be used in most persons.

The toxicity of free gadolinium ions in animals is due to interference with a number of calcium-ion channel dependent processes.

[60] In patients with kidney failure, there is a risk of a rare but serious illness called nephrogenic systemic fibrosis (NSF)[61] that is caused by the use of gadolinium-based contrast agents.

Because of the risk of NSF, use of these agents is not recommended for any individual with end-stage kidney failure as they may require emergent dialysis.

If a contrast-enhanced MRI must be performed on a dialysis patient, it is recommended that certain high-risk contrast agents be avoided but not that a lower dose be considered.

[62] The American College of Radiology recommends that contrast-enhanced MRI examinations be performed as closely before dialysis as possible as a precautionary measure, although this has not been proven to reduce the likelihood of developing NSF.

[65] Long-term environmental impacts of gadolinium contamination due to human usage are a topic of ongoing research.