Gadolinium

Gadolinium is a chemical element with the symbol Gd and atomic number 64. It is a member of the lanthanide series, a group of rare earth metals. In its pure form it is a silvery-white metal that tarnishes in air and is reactive with water upon heating; in practice it is mostly used in compounds.

Gadolinium occurs in minerals such as gadolinite and is not found free in nature. It is extracted from rare-earth ores and separated by ion-exchange or solvent extraction techniques. The element has several stable isotopes, with gadolinium-157 notable for having one of the highest thermal neutron capture cross sections among stable isotopes. The most common oxidation state is +3, and the Gd3+ ion is highly paramagnetic due to its seven unpaired f-electrons.

Applications of gadolinium include magnetic resonance imaging (MRI) contrast agents, where chelated gadolinium enhances imaging while reducing toxicity. Gadolinium compounds are also used as neutron absorbers in nuclear reactors and as components in phosphors, scintillators, and certain magnetic materials such as gadolinium gallium garnet. The element plays a role in some laser systems and specialized optical devices as well.

Safety and handling notes emphasize that gadolinium-based contrast agents are generally safe for people with normal kidney function, but can pose a risk of nephrogenic systemic fibrosis in patients with kidney dysfunction. Some chelate formulations are preferred for their improved safety profile, particularly macrocyclic over linear chelates. Handling gadolinium metal requires standard precautions for reactive metals, including protection against oxidation and inhalation of dust.

History: gadolinium was discovered in 1880 by Jean Charles Galissard de Marignac, who isolated it from gadolinite and named the element in honor of Johan Gadolin, a Finnish chemist who first described the mineral’s oxide.